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Linux/include/linux/sched.h

  1 #ifndef _LINUX_SCHED_H
  2 #define _LINUX_SCHED_H
  3 
  4 #include <uapi/linux/sched.h>
  5 
  6 
  7 struct sched_param {
  8         int sched_priority;
  9 };
 10 
 11 #include <asm/param.h>  /* for HZ */
 12 
 13 #include <linux/capability.h>
 14 #include <linux/threads.h>
 15 #include <linux/kernel.h>
 16 #include <linux/types.h>
 17 #include <linux/timex.h>
 18 #include <linux/jiffies.h>
 19 #include <linux/plist.h>
 20 #include <linux/rbtree.h>
 21 #include <linux/thread_info.h>
 22 #include <linux/cpumask.h>
 23 #include <linux/errno.h>
 24 #include <linux/nodemask.h>
 25 #include <linux/mm_types.h>
 26 #include <linux/preempt_mask.h>
 27 
 28 #include <asm/page.h>
 29 #include <asm/ptrace.h>
 30 #include <asm/cputime.h>
 31 
 32 #include <linux/smp.h>
 33 #include <linux/sem.h>
 34 #include <linux/signal.h>
 35 #include <linux/compiler.h>
 36 #include <linux/completion.h>
 37 #include <linux/pid.h>
 38 #include <linux/percpu.h>
 39 #include <linux/topology.h>
 40 #include <linux/proportions.h>
 41 #include <linux/seccomp.h>
 42 #include <linux/rcupdate.h>
 43 #include <linux/rculist.h>
 44 #include <linux/rtmutex.h>
 45 
 46 #include <linux/time.h>
 47 #include <linux/param.h>
 48 #include <linux/resource.h>
 49 #include <linux/timer.h>
 50 #include <linux/hrtimer.h>
 51 #include <linux/task_io_accounting.h>
 52 #include <linux/latencytop.h>
 53 #include <linux/cred.h>
 54 #include <linux/llist.h>
 55 #include <linux/uidgid.h>
 56 #include <linux/gfp.h>
 57 
 58 #include <asm/processor.h>
 59 
 60 #define SCHED_ATTR_SIZE_VER0    48      /* sizeof first published struct */
 61 
 62 /*
 63  * Extended scheduling parameters data structure.
 64  *
 65  * This is needed because the original struct sched_param can not be
 66  * altered without introducing ABI issues with legacy applications
 67  * (e.g., in sched_getparam()).
 68  *
 69  * However, the possibility of specifying more than just a priority for
 70  * the tasks may be useful for a wide variety of application fields, e.g.,
 71  * multimedia, streaming, automation and control, and many others.
 72  *
 73  * This variant (sched_attr) is meant at describing a so-called
 74  * sporadic time-constrained task. In such model a task is specified by:
 75  *  - the activation period or minimum instance inter-arrival time;
 76  *  - the maximum (or average, depending on the actual scheduling
 77  *    discipline) computation time of all instances, a.k.a. runtime;
 78  *  - the deadline (relative to the actual activation time) of each
 79  *    instance.
 80  * Very briefly, a periodic (sporadic) task asks for the execution of
 81  * some specific computation --which is typically called an instance--
 82  * (at most) every period. Moreover, each instance typically lasts no more
 83  * than the runtime and must be completed by time instant t equal to
 84  * the instance activation time + the deadline.
 85  *
 86  * This is reflected by the actual fields of the sched_attr structure:
 87  *
 88  *  @size               size of the structure, for fwd/bwd compat.
 89  *
 90  *  @sched_policy       task's scheduling policy
 91  *  @sched_flags        for customizing the scheduler behaviour
 92  *  @sched_nice         task's nice value      (SCHED_NORMAL/BATCH)
 93  *  @sched_priority     task's static priority (SCHED_FIFO/RR)
 94  *  @sched_deadline     representative of the task's deadline
 95  *  @sched_runtime      representative of the task's runtime
 96  *  @sched_period       representative of the task's period
 97  *
 98  * Given this task model, there are a multiplicity of scheduling algorithms
 99  * and policies, that can be used to ensure all the tasks will make their
100  * timing constraints.
101  *
102  * As of now, the SCHED_DEADLINE policy (sched_dl scheduling class) is the
103  * only user of this new interface. More information about the algorithm
104  * available in the scheduling class file or in Documentation/.
105  */
106 struct sched_attr {
107         u32 size;
108 
109         u32 sched_policy;
110         u64 sched_flags;
111 
112         /* SCHED_NORMAL, SCHED_BATCH */
113         s32 sched_nice;
114 
115         /* SCHED_FIFO, SCHED_RR */
116         u32 sched_priority;
117 
118         /* SCHED_DEADLINE */
119         u64 sched_runtime;
120         u64 sched_deadline;
121         u64 sched_period;
122 };
123 
124 struct exec_domain;
125 struct futex_pi_state;
126 struct robust_list_head;
127 struct bio_list;
128 struct fs_struct;
129 struct perf_event_context;
130 struct blk_plug;
131 struct filename;
132 
133 /*
134  * List of flags we want to share for kernel threads,
135  * if only because they are not used by them anyway.
136  */
137 #define CLONE_KERNEL    (CLONE_FS | CLONE_FILES | CLONE_SIGHAND)
138 
139 /*
140  * These are the constant used to fake the fixed-point load-average
141  * counting. Some notes:
142  *  - 11 bit fractions expand to 22 bits by the multiplies: this gives
143  *    a load-average precision of 10 bits integer + 11 bits fractional
144  *  - if you want to count load-averages more often, you need more
145  *    precision, or rounding will get you. With 2-second counting freq,
146  *    the EXP_n values would be 1981, 2034 and 2043 if still using only
147  *    11 bit fractions.
148  */
149 extern unsigned long avenrun[];         /* Load averages */
150 extern void get_avenrun(unsigned long *loads, unsigned long offset, int shift);
151 
152 #define FSHIFT          11              /* nr of bits of precision */
153 #define FIXED_1         (1<<FSHIFT)     /* 1.0 as fixed-point */
154 #define LOAD_FREQ       (5*HZ+1)        /* 5 sec intervals */
155 #define EXP_1           1884            /* 1/exp(5sec/1min) as fixed-point */
156 #define EXP_5           2014            /* 1/exp(5sec/5min) */
157 #define EXP_15          2037            /* 1/exp(5sec/15min) */
158 
159 #define CALC_LOAD(load,exp,n) \
160         load *= exp; \
161         load += n*(FIXED_1-exp); \
162         load >>= FSHIFT;
163 
164 extern unsigned long total_forks;
165 extern int nr_threads;
166 DECLARE_PER_CPU(unsigned long, process_counts);
167 extern int nr_processes(void);
168 extern unsigned long nr_running(void);
169 extern unsigned long nr_iowait(void);
170 extern unsigned long nr_iowait_cpu(int cpu);
171 extern unsigned long this_cpu_load(void);
172 
173 
174 extern void calc_global_load(unsigned long ticks);
175 extern void update_cpu_load_nohz(void);
176 
177 extern unsigned long get_parent_ip(unsigned long addr);
178 
179 extern void dump_cpu_task(int cpu);
180 
181 struct seq_file;
182 struct cfs_rq;
183 struct task_group;
184 #ifdef CONFIG_SCHED_DEBUG
185 extern void proc_sched_show_task(struct task_struct *p, struct seq_file *m);
186 extern void proc_sched_set_task(struct task_struct *p);
187 extern void
188 print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq);
189 #endif
190 
191 /*
192  * Task state bitmask. NOTE! These bits are also
193  * encoded in fs/proc/array.c: get_task_state().
194  *
195  * We have two separate sets of flags: task->state
196  * is about runnability, while task->exit_state are
197  * about the task exiting. Confusing, but this way
198  * modifying one set can't modify the other one by
199  * mistake.
200  */
201 #define TASK_RUNNING            0
202 #define TASK_INTERRUPTIBLE      1
203 #define TASK_UNINTERRUPTIBLE    2
204 #define __TASK_STOPPED          4
205 #define __TASK_TRACED           8
206 /* in tsk->exit_state */
207 #define EXIT_ZOMBIE             16
208 #define EXIT_DEAD               32
209 /* in tsk->state again */
210 #define TASK_DEAD               64
211 #define TASK_WAKEKILL           128
212 #define TASK_WAKING             256
213 #define TASK_PARKED             512
214 #define TASK_STATE_MAX          1024
215 
216 #define TASK_STATE_TO_CHAR_STR "RSDTtZXxKWP"
217 
218 extern char ___assert_task_state[1 - 2*!!(
219                 sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1)];
220 
221 /* Convenience macros for the sake of set_task_state */
222 #define TASK_KILLABLE           (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
223 #define TASK_STOPPED            (TASK_WAKEKILL | __TASK_STOPPED)
224 #define TASK_TRACED             (TASK_WAKEKILL | __TASK_TRACED)
225 
226 /* Convenience macros for the sake of wake_up */
227 #define TASK_NORMAL             (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)
228 #define TASK_ALL                (TASK_NORMAL | __TASK_STOPPED | __TASK_TRACED)
229 
230 /* get_task_state() */
231 #define TASK_REPORT             (TASK_RUNNING | TASK_INTERRUPTIBLE | \
232                                  TASK_UNINTERRUPTIBLE | __TASK_STOPPED | \
233                                  __TASK_TRACED | EXIT_ZOMBIE | EXIT_DEAD)
234 
235 #define task_is_traced(task)    ((task->state & __TASK_TRACED) != 0)
236 #define task_is_stopped(task)   ((task->state & __TASK_STOPPED) != 0)
237 #define task_is_stopped_or_traced(task) \
238                         ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
239 #define task_contributes_to_load(task)  \
240                                 ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
241                                  (task->flags & PF_FROZEN) == 0)
242 
243 #define __set_task_state(tsk, state_value)              \
244         do { (tsk)->state = (state_value); } while (0)
245 #define set_task_state(tsk, state_value)                \
246         set_mb((tsk)->state, (state_value))
247 
248 /*
249  * set_current_state() includes a barrier so that the write of current->state
250  * is correctly serialised wrt the caller's subsequent test of whether to
251  * actually sleep:
252  *
253  *      set_current_state(TASK_UNINTERRUPTIBLE);
254  *      if (do_i_need_to_sleep())
255  *              schedule();
256  *
257  * If the caller does not need such serialisation then use __set_current_state()
258  */
259 #define __set_current_state(state_value)                        \
260         do { current->state = (state_value); } while (0)
261 #define set_current_state(state_value)          \
262         set_mb(current->state, (state_value))
263 
264 /* Task command name length */
265 #define TASK_COMM_LEN 16
266 
267 #include <linux/spinlock.h>
268 
269 /*
270  * This serializes "schedule()" and also protects
271  * the run-queue from deletions/modifications (but
272  * _adding_ to the beginning of the run-queue has
273  * a separate lock).
274  */
275 extern rwlock_t tasklist_lock;
276 extern spinlock_t mmlist_lock;
277 
278 struct task_struct;
279 
280 #ifdef CONFIG_PROVE_RCU
281 extern int lockdep_tasklist_lock_is_held(void);
282 #endif /* #ifdef CONFIG_PROVE_RCU */
283 
284 extern void sched_init(void);
285 extern void sched_init_smp(void);
286 extern asmlinkage void schedule_tail(struct task_struct *prev);
287 extern void init_idle(struct task_struct *idle, int cpu);
288 extern void init_idle_bootup_task(struct task_struct *idle);
289 
290 extern int runqueue_is_locked(int cpu);
291 
292 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
293 extern void nohz_balance_enter_idle(int cpu);
294 extern void set_cpu_sd_state_idle(void);
295 extern int get_nohz_timer_target(void);
296 #else
297 static inline void nohz_balance_enter_idle(int cpu) { }
298 static inline void set_cpu_sd_state_idle(void) { }
299 #endif
300 
301 /*
302  * Only dump TASK_* tasks. (0 for all tasks)
303  */
304 extern void show_state_filter(unsigned long state_filter);
305 
306 static inline void show_state(void)
307 {
308         show_state_filter(0);
309 }
310 
311 extern void show_regs(struct pt_regs *);
312 
313 /*
314  * TASK is a pointer to the task whose backtrace we want to see (or NULL for current
315  * task), SP is the stack pointer of the first frame that should be shown in the back
316  * trace (or NULL if the entire call-chain of the task should be shown).
317  */
318 extern void show_stack(struct task_struct *task, unsigned long *sp);
319 
320 void io_schedule(void);
321 long io_schedule_timeout(long timeout);
322 
323 extern void cpu_init (void);
324 extern void trap_init(void);
325 extern void update_process_times(int user);
326 extern void scheduler_tick(void);
327 
328 extern void sched_show_task(struct task_struct *p);
329 
330 #ifdef CONFIG_LOCKUP_DETECTOR
331 extern void touch_softlockup_watchdog(void);
332 extern void touch_softlockup_watchdog_sync(void);
333 extern void touch_all_softlockup_watchdogs(void);
334 extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
335                                   void __user *buffer,
336                                   size_t *lenp, loff_t *ppos);
337 extern unsigned int  softlockup_panic;
338 void lockup_detector_init(void);
339 #else
340 static inline void touch_softlockup_watchdog(void)
341 {
342 }
343 static inline void touch_softlockup_watchdog_sync(void)
344 {
345 }
346 static inline void touch_all_softlockup_watchdogs(void)
347 {
348 }
349 static inline void lockup_detector_init(void)
350 {
351 }
352 #endif
353 
354 #ifdef CONFIG_DETECT_HUNG_TASK
355 void reset_hung_task_detector(void);
356 #else
357 static inline void reset_hung_task_detector(void)
358 {
359 }
360 #endif
361 
362 /* Attach to any functions which should be ignored in wchan output. */
363 #define __sched         __attribute__((__section__(".sched.text")))
364 
365 /* Linker adds these: start and end of __sched functions */
366 extern char __sched_text_start[], __sched_text_end[];
367 
368 /* Is this address in the __sched functions? */
369 extern int in_sched_functions(unsigned long addr);
370 
371 #define MAX_SCHEDULE_TIMEOUT    LONG_MAX
372 extern signed long schedule_timeout(signed long timeout);
373 extern signed long schedule_timeout_interruptible(signed long timeout);
374 extern signed long schedule_timeout_killable(signed long timeout);
375 extern signed long schedule_timeout_uninterruptible(signed long timeout);
376 asmlinkage void schedule(void);
377 extern void schedule_preempt_disabled(void);
378 
379 struct nsproxy;
380 struct user_namespace;
381 
382 #ifdef CONFIG_MMU
383 extern void arch_pick_mmap_layout(struct mm_struct *mm);
384 extern unsigned long
385 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
386                        unsigned long, unsigned long);
387 extern unsigned long
388 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
389                           unsigned long len, unsigned long pgoff,
390                           unsigned long flags);
391 #else
392 static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
393 #endif
394 
395 #define SUID_DUMP_DISABLE       0       /* No setuid dumping */
396 #define SUID_DUMP_USER          1       /* Dump as user of process */
397 #define SUID_DUMP_ROOT          2       /* Dump as root */
398 
399 /* mm flags */
400 
401 /* for SUID_DUMP_* above */
402 #define MMF_DUMPABLE_BITS 2
403 #define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)
404 
405 extern void set_dumpable(struct mm_struct *mm, int value);
406 /*
407  * This returns the actual value of the suid_dumpable flag. For things
408  * that are using this for checking for privilege transitions, it must
409  * test against SUID_DUMP_USER rather than treating it as a boolean
410  * value.
411  */
412 static inline int __get_dumpable(unsigned long mm_flags)
413 {
414         return mm_flags & MMF_DUMPABLE_MASK;
415 }
416 
417 static inline int get_dumpable(struct mm_struct *mm)
418 {
419         return __get_dumpable(mm->flags);
420 }
421 
422 /* coredump filter bits */
423 #define MMF_DUMP_ANON_PRIVATE   2
424 #define MMF_DUMP_ANON_SHARED    3
425 #define MMF_DUMP_MAPPED_PRIVATE 4
426 #define MMF_DUMP_MAPPED_SHARED  5
427 #define MMF_DUMP_ELF_HEADERS    6
428 #define MMF_DUMP_HUGETLB_PRIVATE 7
429 #define MMF_DUMP_HUGETLB_SHARED  8
430 
431 #define MMF_DUMP_FILTER_SHIFT   MMF_DUMPABLE_BITS
432 #define MMF_DUMP_FILTER_BITS    7
433 #define MMF_DUMP_FILTER_MASK \
434         (((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
435 #define MMF_DUMP_FILTER_DEFAULT \
436         ((1 << MMF_DUMP_ANON_PRIVATE) | (1 << MMF_DUMP_ANON_SHARED) |\
437          (1 << MMF_DUMP_HUGETLB_PRIVATE) | MMF_DUMP_MASK_DEFAULT_ELF)
438 
439 #ifdef CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS
440 # define MMF_DUMP_MASK_DEFAULT_ELF      (1 << MMF_DUMP_ELF_HEADERS)
441 #else
442 # define MMF_DUMP_MASK_DEFAULT_ELF      0
443 #endif
444                                         /* leave room for more dump flags */
445 #define MMF_VM_MERGEABLE        16      /* KSM may merge identical pages */
446 #define MMF_VM_HUGEPAGE         17      /* set when VM_HUGEPAGE is set on vma */
447 #define MMF_EXE_FILE_CHANGED    18      /* see prctl_set_mm_exe_file() */
448 
449 #define MMF_HAS_UPROBES         19      /* has uprobes */
450 #define MMF_RECALC_UPROBES      20      /* MMF_HAS_UPROBES can be wrong */
451 
452 #define MMF_INIT_MASK           (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
453 
454 struct sighand_struct {
455         atomic_t                count;
456         struct k_sigaction      action[_NSIG];
457         spinlock_t              siglock;
458         wait_queue_head_t       signalfd_wqh;
459 };
460 
461 struct pacct_struct {
462         int                     ac_flag;
463         long                    ac_exitcode;
464         unsigned long           ac_mem;
465         cputime_t               ac_utime, ac_stime;
466         unsigned long           ac_minflt, ac_majflt;
467 };
468 
469 struct cpu_itimer {
470         cputime_t expires;
471         cputime_t incr;
472         u32 error;
473         u32 incr_error;
474 };
475 
476 /**
477  * struct cputime - snaphsot of system and user cputime
478  * @utime: time spent in user mode
479  * @stime: time spent in system mode
480  *
481  * Gathers a generic snapshot of user and system time.
482  */
483 struct cputime {
484         cputime_t utime;
485         cputime_t stime;
486 };
487 
488 /**
489  * struct task_cputime - collected CPU time counts
490  * @utime:              time spent in user mode, in &cputime_t units
491  * @stime:              time spent in kernel mode, in &cputime_t units
492  * @sum_exec_runtime:   total time spent on the CPU, in nanoseconds
493  *
494  * This is an extension of struct cputime that includes the total runtime
495  * spent by the task from the scheduler point of view.
496  *
497  * As a result, this structure groups together three kinds of CPU time
498  * that are tracked for threads and thread groups.  Most things considering
499  * CPU time want to group these counts together and treat all three
500  * of them in parallel.
501  */
502 struct task_cputime {
503         cputime_t utime;
504         cputime_t stime;
505         unsigned long long sum_exec_runtime;
506 };
507 /* Alternate field names when used to cache expirations. */
508 #define prof_exp        stime
509 #define virt_exp        utime
510 #define sched_exp       sum_exec_runtime
511 
512 #define INIT_CPUTIME    \
513         (struct task_cputime) {                                 \
514                 .utime = 0,                                     \
515                 .stime = 0,                                     \
516                 .sum_exec_runtime = 0,                          \
517         }
518 
519 #ifdef CONFIG_PREEMPT_COUNT
520 #define PREEMPT_DISABLED        (1 + PREEMPT_ENABLED)
521 #else
522 #define PREEMPT_DISABLED        PREEMPT_ENABLED
523 #endif
524 
525 /*
526  * Disable preemption until the scheduler is running.
527  * Reset by start_kernel()->sched_init()->init_idle().
528  *
529  * We include PREEMPT_ACTIVE to avoid cond_resched() from working
530  * before the scheduler is active -- see should_resched().
531  */
532 #define INIT_PREEMPT_COUNT      (PREEMPT_DISABLED + PREEMPT_ACTIVE)
533 
534 /**
535  * struct thread_group_cputimer - thread group interval timer counts
536  * @cputime:            thread group interval timers.
537  * @running:            non-zero when there are timers running and
538  *                      @cputime receives updates.
539  * @lock:               lock for fields in this struct.
540  *
541  * This structure contains the version of task_cputime, above, that is
542  * used for thread group CPU timer calculations.
543  */
544 struct thread_group_cputimer {
545         struct task_cputime cputime;
546         int running;
547         raw_spinlock_t lock;
548 };
549 
550 #include <linux/rwsem.h>
551 struct autogroup;
552 
553 /*
554  * NOTE! "signal_struct" does not have its own
555  * locking, because a shared signal_struct always
556  * implies a shared sighand_struct, so locking
557  * sighand_struct is always a proper superset of
558  * the locking of signal_struct.
559  */
560 struct signal_struct {
561         atomic_t                sigcnt;
562         atomic_t                live;
563         int                     nr_threads;
564         struct list_head        thread_head;
565 
566         wait_queue_head_t       wait_chldexit;  /* for wait4() */
567 
568         /* current thread group signal load-balancing target: */
569         struct task_struct      *curr_target;
570 
571         /* shared signal handling: */
572         struct sigpending       shared_pending;
573 
574         /* thread group exit support */
575         int                     group_exit_code;
576         /* overloaded:
577          * - notify group_exit_task when ->count is equal to notify_count
578          * - everyone except group_exit_task is stopped during signal delivery
579          *   of fatal signals, group_exit_task processes the signal.
580          */
581         int                     notify_count;
582         struct task_struct      *group_exit_task;
583 
584         /* thread group stop support, overloads group_exit_code too */
585         int                     group_stop_count;
586         unsigned int            flags; /* see SIGNAL_* flags below */
587 
588         /*
589          * PR_SET_CHILD_SUBREAPER marks a process, like a service
590          * manager, to re-parent orphan (double-forking) child processes
591          * to this process instead of 'init'. The service manager is
592          * able to receive SIGCHLD signals and is able to investigate
593          * the process until it calls wait(). All children of this
594          * process will inherit a flag if they should look for a
595          * child_subreaper process at exit.
596          */
597         unsigned int            is_child_subreaper:1;
598         unsigned int            has_child_subreaper:1;
599 
600         /* POSIX.1b Interval Timers */
601         int                     posix_timer_id;
602         struct list_head        posix_timers;
603 
604         /* ITIMER_REAL timer for the process */
605         struct hrtimer real_timer;
606         struct pid *leader_pid;
607         ktime_t it_real_incr;
608 
609         /*
610          * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
611          * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
612          * values are defined to 0 and 1 respectively
613          */
614         struct cpu_itimer it[2];
615 
616         /*
617          * Thread group totals for process CPU timers.
618          * See thread_group_cputimer(), et al, for details.
619          */
620         struct thread_group_cputimer cputimer;
621 
622         /* Earliest-expiration cache. */
623         struct task_cputime cputime_expires;
624 
625         struct list_head cpu_timers[3];
626 
627         struct pid *tty_old_pgrp;
628 
629         /* boolean value for session group leader */
630         int leader;
631 
632         struct tty_struct *tty; /* NULL if no tty */
633 
634 #ifdef CONFIG_SCHED_AUTOGROUP
635         struct autogroup *autogroup;
636 #endif
637         /*
638          * Cumulative resource counters for dead threads in the group,
639          * and for reaped dead child processes forked by this group.
640          * Live threads maintain their own counters and add to these
641          * in __exit_signal, except for the group leader.
642          */
643         cputime_t utime, stime, cutime, cstime;
644         cputime_t gtime;
645         cputime_t cgtime;
646 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
647         struct cputime prev_cputime;
648 #endif
649         unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
650         unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
651         unsigned long inblock, oublock, cinblock, coublock;
652         unsigned long maxrss, cmaxrss;
653         struct task_io_accounting ioac;
654 
655         /*
656          * Cumulative ns of schedule CPU time fo dead threads in the
657          * group, not including a zombie group leader, (This only differs
658          * from jiffies_to_ns(utime + stime) if sched_clock uses something
659          * other than jiffies.)
660          */
661         unsigned long long sum_sched_runtime;
662 
663         /*
664          * We don't bother to synchronize most readers of this at all,
665          * because there is no reader checking a limit that actually needs
666          * to get both rlim_cur and rlim_max atomically, and either one
667          * alone is a single word that can safely be read normally.
668          * getrlimit/setrlimit use task_lock(current->group_leader) to
669          * protect this instead of the siglock, because they really
670          * have no need to disable irqs.
671          */
672         struct rlimit rlim[RLIM_NLIMITS];
673 
674 #ifdef CONFIG_BSD_PROCESS_ACCT
675         struct pacct_struct pacct;      /* per-process accounting information */
676 #endif
677 #ifdef CONFIG_TASKSTATS
678         struct taskstats *stats;
679 #endif
680 #ifdef CONFIG_AUDIT
681         unsigned audit_tty;
682         unsigned audit_tty_log_passwd;
683         struct tty_audit_buf *tty_audit_buf;
684 #endif
685 #ifdef CONFIG_CGROUPS
686         /*
687          * group_rwsem prevents new tasks from entering the threadgroup and
688          * member tasks from exiting,a more specifically, setting of
689          * PF_EXITING.  fork and exit paths are protected with this rwsem
690          * using threadgroup_change_begin/end().  Users which require
691          * threadgroup to remain stable should use threadgroup_[un]lock()
692          * which also takes care of exec path.  Currently, cgroup is the
693          * only user.
694          */
695         struct rw_semaphore group_rwsem;
696 #endif
697 
698         oom_flags_t oom_flags;
699         short oom_score_adj;            /* OOM kill score adjustment */
700         short oom_score_adj_min;        /* OOM kill score adjustment min value.
701                                          * Only settable by CAP_SYS_RESOURCE. */
702 
703         struct mutex cred_guard_mutex;  /* guard against foreign influences on
704                                          * credential calculations
705                                          * (notably. ptrace) */
706 };
707 
708 /*
709  * Bits in flags field of signal_struct.
710  */
711 #define SIGNAL_STOP_STOPPED     0x00000001 /* job control stop in effect */
712 #define SIGNAL_STOP_CONTINUED   0x00000002 /* SIGCONT since WCONTINUED reap */
713 #define SIGNAL_GROUP_EXIT       0x00000004 /* group exit in progress */
714 #define SIGNAL_GROUP_COREDUMP   0x00000008 /* coredump in progress */
715 /*
716  * Pending notifications to parent.
717  */
718 #define SIGNAL_CLD_STOPPED      0x00000010
719 #define SIGNAL_CLD_CONTINUED    0x00000020
720 #define SIGNAL_CLD_MASK         (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)
721 
722 #define SIGNAL_UNKILLABLE       0x00000040 /* for init: ignore fatal signals */
723 
724 /* If true, all threads except ->group_exit_task have pending SIGKILL */
725 static inline int signal_group_exit(const struct signal_struct *sig)
726 {
727         return  (sig->flags & SIGNAL_GROUP_EXIT) ||
728                 (sig->group_exit_task != NULL);
729 }
730 
731 /*
732  * Some day this will be a full-fledged user tracking system..
733  */
734 struct user_struct {
735         atomic_t __count;       /* reference count */
736         atomic_t processes;     /* How many processes does this user have? */
737         atomic_t files;         /* How many open files does this user have? */
738         atomic_t sigpending;    /* How many pending signals does this user have? */
739 #ifdef CONFIG_INOTIFY_USER
740         atomic_t inotify_watches; /* How many inotify watches does this user have? */
741         atomic_t inotify_devs;  /* How many inotify devs does this user have opened? */
742 #endif
743 #ifdef CONFIG_FANOTIFY
744         atomic_t fanotify_listeners;
745 #endif
746 #ifdef CONFIG_EPOLL
747         atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
748 #endif
749 #ifdef CONFIG_POSIX_MQUEUE
750         /* protected by mq_lock */
751         unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */
752 #endif
753         unsigned long locked_shm; /* How many pages of mlocked shm ? */
754 
755 #ifdef CONFIG_KEYS
756         struct key *uid_keyring;        /* UID specific keyring */
757         struct key *session_keyring;    /* UID's default session keyring */
758 #endif
759 
760         /* Hash table maintenance information */
761         struct hlist_node uidhash_node;
762         kuid_t uid;
763 
764 #ifdef CONFIG_PERF_EVENTS
765         atomic_long_t locked_vm;
766 #endif
767 };
768 
769 extern int uids_sysfs_init(void);
770 
771 extern struct user_struct *find_user(kuid_t);
772 
773 extern struct user_struct root_user;
774 #define INIT_USER (&root_user)
775 
776 
777 struct backing_dev_info;
778 struct reclaim_state;
779 
780 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
781 struct sched_info {
782         /* cumulative counters */
783         unsigned long pcount;         /* # of times run on this cpu */
784         unsigned long long run_delay; /* time spent waiting on a runqueue */
785 
786         /* timestamps */
787         unsigned long long last_arrival,/* when we last ran on a cpu */
788                            last_queued; /* when we were last queued to run */
789 };
790 #endif /* defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) */
791 
792 #ifdef CONFIG_TASK_DELAY_ACCT
793 struct task_delay_info {
794         spinlock_t      lock;
795         unsigned int    flags;  /* Private per-task flags */
796 
797         /* For each stat XXX, add following, aligned appropriately
798          *
799          * struct timespec XXX_start, XXX_end;
800          * u64 XXX_delay;
801          * u32 XXX_count;
802          *
803          * Atomicity of updates to XXX_delay, XXX_count protected by
804          * single lock above (split into XXX_lock if contention is an issue).
805          */
806 
807         /*
808          * XXX_count is incremented on every XXX operation, the delay
809          * associated with the operation is added to XXX_delay.
810          * XXX_delay contains the accumulated delay time in nanoseconds.
811          */
812         struct timespec blkio_start, blkio_end; /* Shared by blkio, swapin */
813         u64 blkio_delay;        /* wait for sync block io completion */
814         u64 swapin_delay;       /* wait for swapin block io completion */
815         u32 blkio_count;        /* total count of the number of sync block */
816                                 /* io operations performed */
817         u32 swapin_count;       /* total count of the number of swapin block */
818                                 /* io operations performed */
819 
820         struct timespec freepages_start, freepages_end;
821         u64 freepages_delay;    /* wait for memory reclaim */
822         u32 freepages_count;    /* total count of memory reclaim */
823 };
824 #endif  /* CONFIG_TASK_DELAY_ACCT */
825 
826 static inline int sched_info_on(void)
827 {
828 #ifdef CONFIG_SCHEDSTATS
829         return 1;
830 #elif defined(CONFIG_TASK_DELAY_ACCT)
831         extern int delayacct_on;
832         return delayacct_on;
833 #else
834         return 0;
835 #endif
836 }
837 
838 enum cpu_idle_type {
839         CPU_IDLE,
840         CPU_NOT_IDLE,
841         CPU_NEWLY_IDLE,
842         CPU_MAX_IDLE_TYPES
843 };
844 
845 /*
846  * Increase resolution of cpu_power calculations
847  */
848 #define SCHED_POWER_SHIFT       10
849 #define SCHED_POWER_SCALE       (1L << SCHED_POWER_SHIFT)
850 
851 /*
852  * sched-domains (multiprocessor balancing) declarations:
853  */
854 #ifdef CONFIG_SMP
855 #define SD_LOAD_BALANCE         0x0001  /* Do load balancing on this domain. */
856 #define SD_BALANCE_NEWIDLE      0x0002  /* Balance when about to become idle */
857 #define SD_BALANCE_EXEC         0x0004  /* Balance on exec */
858 #define SD_BALANCE_FORK         0x0008  /* Balance on fork, clone */
859 #define SD_BALANCE_WAKE         0x0010  /* Balance on wakeup */
860 #define SD_WAKE_AFFINE          0x0020  /* Wake task to waking CPU */
861 #define SD_SHARE_CPUPOWER       0x0080  /* Domain members share cpu power */
862 #define SD_SHARE_PKG_RESOURCES  0x0200  /* Domain members share cpu pkg resources */
863 #define SD_SERIALIZE            0x0400  /* Only a single load balancing instance */
864 #define SD_ASYM_PACKING         0x0800  /* Place busy groups earlier in the domain */
865 #define SD_PREFER_SIBLING       0x1000  /* Prefer to place tasks in a sibling domain */
866 #define SD_OVERLAP              0x2000  /* sched_domains of this level overlap */
867 #define SD_NUMA                 0x4000  /* cross-node balancing */
868 
869 extern int __weak arch_sd_sibiling_asym_packing(void);
870 
871 struct sched_domain_attr {
872         int relax_domain_level;
873 };
874 
875 #define SD_ATTR_INIT    (struct sched_domain_attr) {    \
876         .relax_domain_level = -1,                       \
877 }
878 
879 extern int sched_domain_level_max;
880 
881 struct sched_group;
882 
883 struct sched_domain {
884         /* These fields must be setup */
885         struct sched_domain *parent;    /* top domain must be null terminated */
886         struct sched_domain *child;     /* bottom domain must be null terminated */
887         struct sched_group *groups;     /* the balancing groups of the domain */
888         unsigned long min_interval;     /* Minimum balance interval ms */
889         unsigned long max_interval;     /* Maximum balance interval ms */
890         unsigned int busy_factor;       /* less balancing by factor if busy */
891         unsigned int imbalance_pct;     /* No balance until over watermark */
892         unsigned int cache_nice_tries;  /* Leave cache hot tasks for # tries */
893         unsigned int busy_idx;
894         unsigned int idle_idx;
895         unsigned int newidle_idx;
896         unsigned int wake_idx;
897         unsigned int forkexec_idx;
898         unsigned int smt_gain;
899 
900         int nohz_idle;                  /* NOHZ IDLE status */
901         int flags;                      /* See SD_* */
902         int level;
903 
904         /* Runtime fields. */
905         unsigned long last_balance;     /* init to jiffies. units in jiffies */
906         unsigned int balance_interval;  /* initialise to 1. units in ms. */
907         unsigned int nr_balance_failed; /* initialise to 0 */
908 
909         /* idle_balance() stats */
910         u64 max_newidle_lb_cost;
911         unsigned long next_decay_max_lb_cost;
912 
913 #ifdef CONFIG_SCHEDSTATS
914         /* load_balance() stats */
915         unsigned int lb_count[CPU_MAX_IDLE_TYPES];
916         unsigned int lb_failed[CPU_MAX_IDLE_TYPES];
917         unsigned int lb_balanced[CPU_MAX_IDLE_TYPES];
918         unsigned int lb_imbalance[CPU_MAX_IDLE_TYPES];
919         unsigned int lb_gained[CPU_MAX_IDLE_TYPES];
920         unsigned int lb_hot_gained[CPU_MAX_IDLE_TYPES];
921         unsigned int lb_nobusyg[CPU_MAX_IDLE_TYPES];
922         unsigned int lb_nobusyq[CPU_MAX_IDLE_TYPES];
923 
924         /* Active load balancing */
925         unsigned int alb_count;
926         unsigned int alb_failed;
927         unsigned int alb_pushed;
928 
929         /* SD_BALANCE_EXEC stats */
930         unsigned int sbe_count;
931         unsigned int sbe_balanced;
932         unsigned int sbe_pushed;
933 
934         /* SD_BALANCE_FORK stats */
935         unsigned int sbf_count;
936         unsigned int sbf_balanced;
937         unsigned int sbf_pushed;
938 
939         /* try_to_wake_up() stats */
940         unsigned int ttwu_wake_remote;
941         unsigned int ttwu_move_affine;
942         unsigned int ttwu_move_balance;
943 #endif
944 #ifdef CONFIG_SCHED_DEBUG
945         char *name;
946 #endif
947         union {
948                 void *private;          /* used during construction */
949                 struct rcu_head rcu;    /* used during destruction */
950         };
951 
952         unsigned int span_weight;
953         /*
954          * Span of all CPUs in this domain.
955          *
956          * NOTE: this field is variable length. (Allocated dynamically
957          * by attaching extra space to the end of the structure,
958          * depending on how many CPUs the kernel has booted up with)
959          */
960         unsigned long span[0];
961 };
962 
963 static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
964 {
965         return to_cpumask(sd->span);
966 }
967 
968 extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
969                                     struct sched_domain_attr *dattr_new);
970 
971 /* Allocate an array of sched domains, for partition_sched_domains(). */
972 cpumask_var_t *alloc_sched_domains(unsigned int ndoms);
973 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms);
974 
975 bool cpus_share_cache(int this_cpu, int that_cpu);
976 
977 #else /* CONFIG_SMP */
978 
979 struct sched_domain_attr;
980 
981 static inline void
982 partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
983                         struct sched_domain_attr *dattr_new)
984 {
985 }
986 
987 static inline bool cpus_share_cache(int this_cpu, int that_cpu)
988 {
989         return true;
990 }
991 
992 #endif  /* !CONFIG_SMP */
993 
994 
995 struct io_context;                      /* See blkdev.h */
996 
997 
998 #ifdef ARCH_HAS_PREFETCH_SWITCH_STACK
999 extern void prefetch_stack(struct task_struct *t);
1000 #else
1001 static inline void prefetch_stack(struct task_struct *t) { }
1002 #endif
1003 
1004 struct audit_context;           /* See audit.c */
1005 struct mempolicy;
1006 struct pipe_inode_info;
1007 struct uts_namespace;
1008 
1009 struct load_weight {
1010         unsigned long weight;
1011         u32 inv_weight;
1012 };
1013 
1014 struct sched_avg {
1015         /*
1016          * These sums represent an infinite geometric series and so are bound
1017          * above by 1024/(1-y).  Thus we only need a u32 to store them for all
1018          * choices of y < 1-2^(-32)*1024.
1019          */
1020         u32 runnable_avg_sum, runnable_avg_period;
1021         u64 last_runnable_update;
1022         s64 decay_count;
1023         unsigned long load_avg_contrib;
1024 };
1025 
1026 #ifdef CONFIG_SCHEDSTATS
1027 struct sched_statistics {
1028         u64                     wait_start;
1029         u64                     wait_max;
1030         u64                     wait_count;
1031         u64                     wait_sum;
1032         u64                     iowait_count;
1033         u64                     iowait_sum;
1034 
1035         u64                     sleep_start;
1036         u64                     sleep_max;
1037         s64                     sum_sleep_runtime;
1038 
1039         u64                     block_start;
1040         u64                     block_max;
1041         u64                     exec_max;
1042         u64                     slice_max;
1043 
1044         u64                     nr_migrations_cold;
1045         u64                     nr_failed_migrations_affine;
1046         u64                     nr_failed_migrations_running;
1047         u64                     nr_failed_migrations_hot;
1048         u64                     nr_forced_migrations;
1049 
1050         u64                     nr_wakeups;
1051         u64                     nr_wakeups_sync;
1052         u64                     nr_wakeups_migrate;
1053         u64                     nr_wakeups_local;
1054         u64                     nr_wakeups_remote;
1055         u64                     nr_wakeups_affine;
1056         u64                     nr_wakeups_affine_attempts;
1057         u64                     nr_wakeups_passive;
1058         u64                     nr_wakeups_idle;
1059 };
1060 #endif
1061 
1062 struct sched_entity {
1063         struct load_weight      load;           /* for load-balancing */
1064         struct rb_node          run_node;
1065         struct list_head        group_node;
1066         unsigned int            on_rq;
1067 
1068         u64                     exec_start;
1069         u64                     sum_exec_runtime;
1070         u64                     vruntime;
1071         u64                     prev_sum_exec_runtime;
1072 
1073         u64                     nr_migrations;
1074 
1075 #ifdef CONFIG_SCHEDSTATS
1076         struct sched_statistics statistics;
1077 #endif
1078 
1079 #ifdef CONFIG_FAIR_GROUP_SCHED
1080         struct sched_entity     *parent;
1081         /* rq on which this entity is (to be) queued: */
1082         struct cfs_rq           *cfs_rq;
1083         /* rq "owned" by this entity/group: */
1084         struct cfs_rq           *my_q;
1085 #endif
1086 
1087 #ifdef CONFIG_SMP
1088         /* Per-entity load-tracking */
1089         struct sched_avg        avg;
1090 #endif
1091 };
1092 
1093 struct sched_rt_entity {
1094         struct list_head run_list;
1095         unsigned long timeout;
1096         unsigned long watchdog_stamp;
1097         unsigned int time_slice;
1098 
1099         struct sched_rt_entity *back;
1100 #ifdef CONFIG_RT_GROUP_SCHED
1101         struct sched_rt_entity  *parent;
1102         /* rq on which this entity is (to be) queued: */
1103         struct rt_rq            *rt_rq;
1104         /* rq "owned" by this entity/group: */
1105         struct rt_rq            *my_q;
1106 #endif
1107 };
1108 
1109 struct sched_dl_entity {
1110         struct rb_node  rb_node;
1111 
1112         /*
1113          * Original scheduling parameters. Copied here from sched_attr
1114          * during sched_setscheduler2(), they will remain the same until
1115          * the next sched_setscheduler2().
1116          */
1117         u64 dl_runtime;         /* maximum runtime for each instance    */
1118         u64 dl_deadline;        /* relative deadline of each instance   */
1119         u64 dl_period;          /* separation of two instances (period) */
1120         u64 dl_bw;              /* dl_runtime / dl_deadline             */
1121 
1122         /*
1123          * Actual scheduling parameters. Initialized with the values above,
1124          * they are continously updated during task execution. Note that
1125          * the remaining runtime could be < 0 in case we are in overrun.
1126          */
1127         s64 runtime;            /* remaining runtime for this instance  */
1128         u64 deadline;           /* absolute deadline for this instance  */
1129         unsigned int flags;     /* specifying the scheduler behaviour   */
1130 
1131         /*
1132          * Some bool flags:
1133          *
1134          * @dl_throttled tells if we exhausted the runtime. If so, the
1135          * task has to wait for a replenishment to be performed at the
1136          * next firing of dl_timer.
1137          *
1138          * @dl_new tells if a new instance arrived. If so we must
1139          * start executing it with full runtime and reset its absolute
1140          * deadline;
1141          *
1142          * @dl_boosted tells if we are boosted due to DI. If so we are
1143          * outside bandwidth enforcement mechanism (but only until we
1144          * exit the critical section).
1145          */
1146         int dl_throttled, dl_new, dl_boosted;
1147 
1148         /*
1149          * Bandwidth enforcement timer. Each -deadline task has its
1150          * own bandwidth to be enforced, thus we need one timer per task.
1151          */
1152         struct hrtimer dl_timer;
1153 };
1154 
1155 struct rcu_node;
1156 
1157 enum perf_event_task_context {
1158         perf_invalid_context = -1,
1159         perf_hw_context = 0,
1160         perf_sw_context,
1161         perf_nr_task_contexts,
1162 };
1163 
1164 struct task_struct {
1165         volatile long state;    /* -1 unrunnable, 0 runnable, >0 stopped */
1166         void *stack;
1167         atomic_t usage;
1168         unsigned int flags;     /* per process flags, defined below */
1169         unsigned int ptrace;
1170 
1171 #ifdef CONFIG_SMP
1172         struct llist_node wake_entry;
1173         int on_cpu;
1174         struct task_struct *last_wakee;
1175         unsigned long wakee_flips;
1176         unsigned long wakee_flip_decay_ts;
1177 
1178         int wake_cpu;
1179 #endif
1180         int on_rq;
1181 
1182         int prio, static_prio, normal_prio;
1183         unsigned int rt_priority;
1184         const struct sched_class *sched_class;
1185         struct sched_entity se;
1186         struct sched_rt_entity rt;
1187 #ifdef CONFIG_CGROUP_SCHED
1188         struct task_group *sched_task_group;
1189 #endif
1190         struct sched_dl_entity dl;
1191 
1192 #ifdef CONFIG_PREEMPT_NOTIFIERS
1193         /* list of struct preempt_notifier: */
1194         struct hlist_head preempt_notifiers;
1195 #endif
1196 
1197 #ifdef CONFIG_BLK_DEV_IO_TRACE
1198         unsigned int btrace_seq;
1199 #endif
1200 
1201         unsigned int policy;
1202         int nr_cpus_allowed;
1203         cpumask_t cpus_allowed;
1204 
1205 #ifdef CONFIG_PREEMPT_RCU
1206         int rcu_read_lock_nesting;
1207         char rcu_read_unlock_special;
1208         struct list_head rcu_node_entry;
1209 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1210 #ifdef CONFIG_TREE_PREEMPT_RCU
1211         struct rcu_node *rcu_blocked_node;
1212 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
1213 #ifdef CONFIG_RCU_BOOST
1214         struct rt_mutex *rcu_boost_mutex;
1215 #endif /* #ifdef CONFIG_RCU_BOOST */
1216 
1217 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1218         struct sched_info sched_info;
1219 #endif
1220 
1221         struct list_head tasks;
1222 #ifdef CONFIG_SMP
1223         struct plist_node pushable_tasks;
1224         struct rb_node pushable_dl_tasks;
1225 #endif
1226 
1227         struct mm_struct *mm, *active_mm;
1228 #ifdef CONFIG_COMPAT_BRK
1229         unsigned brk_randomized:1;
1230 #endif
1231 #if defined(SPLIT_RSS_COUNTING)
1232         struct task_rss_stat    rss_stat;
1233 #endif
1234 /* task state */
1235         int exit_state;
1236         int exit_code, exit_signal;
1237         int pdeath_signal;  /*  The signal sent when the parent dies  */
1238         unsigned int jobctl;    /* JOBCTL_*, siglock protected */
1239 
1240         /* Used for emulating ABI behavior of previous Linux versions */
1241         unsigned int personality;
1242 
1243         unsigned in_execve:1;   /* Tell the LSMs that the process is doing an
1244                                  * execve */
1245         unsigned in_iowait:1;
1246 
1247         /* task may not gain privileges */
1248         unsigned no_new_privs:1;
1249 
1250         /* Revert to default priority/policy when forking */
1251         unsigned sched_reset_on_fork:1;
1252         unsigned sched_contributes_to_load:1;
1253 
1254         pid_t pid;
1255         pid_t tgid;
1256 
1257 #ifdef CONFIG_CC_STACKPROTECTOR
1258         /* Canary value for the -fstack-protector gcc feature */
1259         unsigned long stack_canary;
1260 #endif
1261         /*
1262          * pointers to (original) parent process, youngest child, younger sibling,
1263          * older sibling, respectively.  (p->father can be replaced with
1264          * p->real_parent->pid)
1265          */
1266         struct task_struct __rcu *real_parent; /* real parent process */
1267         struct task_struct __rcu *parent; /* recipient of SIGCHLD, wait4() reports */
1268         /*
1269          * children/sibling forms the list of my natural children
1270          */
1271         struct list_head children;      /* list of my children */
1272         struct list_head sibling;       /* linkage in my parent's children list */
1273         struct task_struct *group_leader;       /* threadgroup leader */
1274 
1275         /*
1276          * ptraced is the list of tasks this task is using ptrace on.
1277          * This includes both natural children and PTRACE_ATTACH targets.
1278          * p->ptrace_entry is p's link on the p->parent->ptraced list.
1279          */
1280         struct list_head ptraced;
1281         struct list_head ptrace_entry;
1282 
1283         /* PID/PID hash table linkage. */
1284         struct pid_link pids[PIDTYPE_MAX];
1285         struct list_head thread_group;
1286         struct list_head thread_node;
1287 
1288         struct completion *vfork_done;          /* for vfork() */
1289         int __user *set_child_tid;              /* CLONE_CHILD_SETTID */
1290         int __user *clear_child_tid;            /* CLONE_CHILD_CLEARTID */
1291 
1292         cputime_t utime, stime, utimescaled, stimescaled;
1293         cputime_t gtime;
1294 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
1295         struct cputime prev_cputime;
1296 #endif
1297 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1298         seqlock_t vtime_seqlock;
1299         unsigned long long vtime_snap;
1300         enum {
1301                 VTIME_SLEEPING = 0,
1302                 VTIME_USER,
1303                 VTIME_SYS,
1304         } vtime_snap_whence;
1305 #endif
1306         unsigned long nvcsw, nivcsw; /* context switch counts */
1307         struct timespec start_time;             /* monotonic time */
1308         struct timespec real_start_time;        /* boot based time */
1309 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
1310         unsigned long min_flt, maj_flt;
1311 
1312         struct task_cputime cputime_expires;
1313         struct list_head cpu_timers[3];
1314 
1315 /* process credentials */
1316         const struct cred __rcu *real_cred; /* objective and real subjective task
1317                                          * credentials (COW) */
1318         const struct cred __rcu *cred;  /* effective (overridable) subjective task
1319                                          * credentials (COW) */
1320         char comm[TASK_COMM_LEN]; /* executable name excluding path
1321                                      - access with [gs]et_task_comm (which lock
1322                                        it with task_lock())
1323                                      - initialized normally by setup_new_exec */
1324 /* file system info */
1325         int link_count, total_link_count;
1326 #ifdef CONFIG_SYSVIPC
1327 /* ipc stuff */
1328         struct sysv_sem sysvsem;
1329 #endif
1330 #ifdef CONFIG_DETECT_HUNG_TASK
1331 /* hung task detection */
1332         unsigned long last_switch_count;
1333 #endif
1334 /* CPU-specific state of this task */
1335         struct thread_struct thread;
1336 /* filesystem information */
1337         struct fs_struct *fs;
1338 /* open file information */
1339         struct files_struct *files;
1340 /* namespaces */
1341         struct nsproxy *nsproxy;
1342 /* signal handlers */
1343         struct signal_struct *signal;
1344         struct sighand_struct *sighand;
1345 
1346         sigset_t blocked, real_blocked;
1347         sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */
1348         struct sigpending pending;
1349 
1350         unsigned long sas_ss_sp;
1351         size_t sas_ss_size;
1352         int (*notifier)(void *priv);
1353         void *notifier_data;
1354         sigset_t *notifier_mask;
1355         struct callback_head *task_works;
1356 
1357         struct audit_context *audit_context;
1358 #ifdef CONFIG_AUDITSYSCALL
1359         kuid_t loginuid;
1360         unsigned int sessionid;
1361 #endif
1362         struct seccomp seccomp;
1363 
1364 /* Thread group tracking */
1365         u32 parent_exec_id;
1366         u32 self_exec_id;
1367 /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed,
1368  * mempolicy */
1369         spinlock_t alloc_lock;
1370 
1371         /* Protection of the PI data structures: */
1372         raw_spinlock_t pi_lock;
1373 
1374 #ifdef CONFIG_RT_MUTEXES
1375         /* PI waiters blocked on a rt_mutex held by this task */
1376         struct rb_root pi_waiters;
1377         struct rb_node *pi_waiters_leftmost;
1378         /* Deadlock detection and priority inheritance handling */
1379         struct rt_mutex_waiter *pi_blocked_on;
1380         /* Top pi_waiters task */
1381         struct task_struct *pi_top_task;
1382 #endif
1383 
1384 #ifdef CONFIG_DEBUG_MUTEXES
1385         /* mutex deadlock detection */
1386         struct mutex_waiter *blocked_on;
1387 #endif
1388 #ifdef CONFIG_TRACE_IRQFLAGS
1389         unsigned int irq_events;
1390         unsigned long hardirq_enable_ip;
1391         unsigned long hardirq_disable_ip;
1392         unsigned int hardirq_enable_event;
1393         unsigned int hardirq_disable_event;
1394         int hardirqs_enabled;
1395         int hardirq_context;
1396         unsigned long softirq_disable_ip;
1397         unsigned long softirq_enable_ip;
1398         unsigned int softirq_disable_event;
1399         unsigned int softirq_enable_event;
1400         int softirqs_enabled;
1401         int softirq_context;
1402 #endif
1403 #ifdef CONFIG_LOCKDEP
1404 # define MAX_LOCK_DEPTH 48UL
1405         u64 curr_chain_key;
1406         int lockdep_depth;
1407         unsigned int lockdep_recursion;
1408         struct held_lock held_locks[MAX_LOCK_DEPTH];
1409         gfp_t lockdep_reclaim_gfp;
1410 #endif
1411 
1412 /* journalling filesystem info */
1413         void *journal_info;
1414 
1415 /* stacked block device info */
1416         struct bio_list *bio_list;
1417 
1418 #ifdef CONFIG_BLOCK
1419 /* stack plugging */
1420         struct blk_plug *plug;
1421 #endif
1422 
1423 /* VM state */
1424         struct reclaim_state *reclaim_state;
1425 
1426         struct backing_dev_info *backing_dev_info;
1427 
1428         struct io_context *io_context;
1429 
1430         unsigned long ptrace_message;
1431         siginfo_t *last_siginfo; /* For ptrace use.  */
1432         struct task_io_accounting ioac;
1433 #if defined(CONFIG_TASK_XACCT)
1434         u64 acct_rss_mem1;      /* accumulated rss usage */
1435         u64 acct_vm_mem1;       /* accumulated virtual memory usage */
1436         cputime_t acct_timexpd; /* stime + utime since last update */
1437 #endif
1438 #ifdef CONFIG_CPUSETS
1439         nodemask_t mems_allowed;        /* Protected by alloc_lock */
1440         seqcount_t mems_allowed_seq;    /* Seqence no to catch updates */
1441         int cpuset_mem_spread_rotor;
1442         int cpuset_slab_spread_rotor;
1443 #endif
1444 #ifdef CONFIG_CGROUPS
1445         /* Control Group info protected by css_set_lock */
1446         struct css_set __rcu *cgroups;
1447         /* cg_list protected by css_set_lock and tsk->alloc_lock */
1448         struct list_head cg_list;
1449 #endif
1450 #ifdef CONFIG_FUTEX
1451         struct robust_list_head __user *robust_list;
1452 #ifdef CONFIG_COMPAT
1453         struct compat_robust_list_head __user *compat_robust_list;
1454 #endif
1455         struct list_head pi_state_list;
1456         struct futex_pi_state *pi_state_cache;
1457 #endif
1458 #ifdef CONFIG_PERF_EVENTS
1459         struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];
1460         struct mutex perf_event_mutex;
1461         struct list_head perf_event_list;
1462 #endif
1463 #ifdef CONFIG_NUMA
1464         struct mempolicy *mempolicy;    /* Protected by alloc_lock */
1465         short il_next;
1466         short pref_node_fork;
1467 #endif
1468 #ifdef CONFIG_NUMA_BALANCING
1469         int numa_scan_seq;
1470         unsigned int numa_scan_period;
1471         unsigned int numa_scan_period_max;
1472         int numa_preferred_nid;
1473         int numa_migrate_deferred;
1474         unsigned long numa_migrate_retry;
1475         u64 node_stamp;                 /* migration stamp  */
1476         struct callback_head numa_work;
1477 
1478         struct list_head numa_entry;
1479         struct numa_group *numa_group;
1480 
1481         /*
1482          * Exponential decaying average of faults on a per-node basis.
1483          * Scheduling placement decisions are made based on the these counts.
1484          * The values remain static for the duration of a PTE scan
1485          */
1486         unsigned long *numa_faults;
1487         unsigned long total_numa_faults;
1488 
1489         /*
1490          * numa_faults_buffer records faults per node during the current
1491          * scan window. When the scan completes, the counts in numa_faults
1492          * decay and these values are copied.
1493          */
1494         unsigned long *numa_faults_buffer;
1495 
1496         /*
1497          * numa_faults_locality tracks if faults recorded during the last
1498          * scan window were remote/local. The task scan period is adapted
1499          * based on the locality of the faults with different weights
1500          * depending on whether they were shared or private faults
1501          */
1502         unsigned long numa_faults_locality[2];
1503 
1504         unsigned long numa_pages_migrated;
1505 #endif /* CONFIG_NUMA_BALANCING */
1506 
1507         struct rcu_head rcu;
1508 
1509         /*
1510          * cache last used pipe for splice
1511          */
1512         struct pipe_inode_info *splice_pipe;
1513 
1514         struct page_frag task_frag;
1515 
1516 #ifdef  CONFIG_TASK_DELAY_ACCT
1517         struct task_delay_info *delays;
1518 #endif
1519 #ifdef CONFIG_FAULT_INJECTION
1520         int make_it_fail;
1521 #endif
1522         /*
1523          * when (nr_dirtied >= nr_dirtied_pause), it's time to call
1524          * balance_dirty_pages() for some dirty throttling pause
1525          */
1526         int nr_dirtied;
1527         int nr_dirtied_pause;
1528         unsigned long dirty_paused_when; /* start of a write-and-pause period */
1529 
1530 #ifdef CONFIG_LATENCYTOP
1531         int latency_record_count;
1532         struct latency_record latency_record[LT_SAVECOUNT];
1533 #endif
1534         /*
1535          * time slack values; these are used to round up poll() and
1536          * select() etc timeout values. These are in nanoseconds.
1537          */
1538         unsigned long timer_slack_ns;
1539         unsigned long default_timer_slack_ns;
1540 
1541 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1542         /* Index of current stored address in ret_stack */
1543         int curr_ret_stack;
1544         /* Stack of return addresses for return function tracing */
1545         struct ftrace_ret_stack *ret_stack;
1546         /* time stamp for last schedule */
1547         unsigned long long ftrace_timestamp;
1548         /*
1549          * Number of functions that haven't been traced
1550          * because of depth overrun.
1551          */
1552         atomic_t trace_overrun;
1553         /* Pause for the tracing */
1554         atomic_t tracing_graph_pause;
1555 #endif
1556 #ifdef CONFIG_TRACING
1557         /* state flags for use by tracers */
1558         unsigned long trace;
1559         /* bitmask and counter of trace recursion */
1560         unsigned long trace_recursion;
1561 #endif /* CONFIG_TRACING */
1562 #ifdef CONFIG_MEMCG /* memcg uses this to do batch job */
1563         struct memcg_batch_info {
1564                 int do_batch;   /* incremented when batch uncharge started */
1565                 struct mem_cgroup *memcg; /* target memcg of uncharge */
1566                 unsigned long nr_pages; /* uncharged usage */
1567                 unsigned long memsw_nr_pages; /* uncharged mem+swap usage */
1568         } memcg_batch;
1569         unsigned int memcg_kmem_skip_account;
1570         struct memcg_oom_info {
1571                 struct mem_cgroup *memcg;
1572                 gfp_t gfp_mask;
1573                 int order;
1574                 unsigned int may_oom:1;
1575         } memcg_oom;
1576 #endif
1577 #ifdef CONFIG_UPROBES
1578         struct uprobe_task *utask;
1579 #endif
1580 #if defined(CONFIG_BCACHE) || defined(CONFIG_BCACHE_MODULE)
1581         unsigned int    sequential_io;
1582         unsigned int    sequential_io_avg;
1583 #endif
1584 };
1585 
1586 /* Future-safe accessor for struct task_struct's cpus_allowed. */
1587 #define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)
1588 
1589 #define TNF_MIGRATED    0x01
1590 #define TNF_NO_GROUP    0x02
1591 #define TNF_SHARED      0x04
1592 #define TNF_FAULT_LOCAL 0x08
1593 
1594 #ifdef CONFIG_NUMA_BALANCING
1595 extern void task_numa_fault(int last_node, int node, int pages, int flags);
1596 extern pid_t task_numa_group_id(struct task_struct *p);
1597 extern void set_numabalancing_state(bool enabled);
1598 extern void task_numa_free(struct task_struct *p);
1599 
1600 extern unsigned int sysctl_numa_balancing_migrate_deferred;
1601 #else
1602 static inline void task_numa_fault(int last_node, int node, int pages,
1603                                    int flags)
1604 {
1605 }
1606 static inline pid_t task_numa_group_id(struct task_struct *p)
1607 {
1608         return 0;
1609 }
1610 static inline void set_numabalancing_state(bool enabled)
1611 {
1612 }
1613 static inline void task_numa_free(struct task_struct *p)
1614 {
1615 }
1616 #endif
1617 
1618 static inline struct pid *task_pid(struct task_struct *task)
1619 {
1620         return task->pids[PIDTYPE_PID].pid;
1621 }
1622 
1623 static inline struct pid *task_tgid(struct task_struct *task)
1624 {
1625         return task->group_leader->pids[PIDTYPE_PID].pid;
1626 }
1627 
1628 /*
1629  * Without tasklist or rcu lock it is not safe to dereference
1630  * the result of task_pgrp/task_session even if task == current,
1631  * we can race with another thread doing sys_setsid/sys_setpgid.
1632  */
1633 static inline struct pid *task_pgrp(struct task_struct *task)
1634 {
1635         return task->group_leader->pids[PIDTYPE_PGID].pid;
1636 }
1637 
1638 static inline struct pid *task_session(struct task_struct *task)
1639 {
1640         return task->group_leader->pids[PIDTYPE_SID].pid;
1641 }
1642 
1643 struct pid_namespace;
1644 
1645 /*
1646  * the helpers to get the task's different pids as they are seen
1647  * from various namespaces
1648  *
1649  * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
1650  * task_xid_vnr()    : virtual id, i.e. the id seen from the pid namespace of
1651  *                     current.
1652  * task_xid_nr_ns()  : id seen from the ns specified;
1653  *
1654  * set_task_vxid()   : assigns a virtual id to a task;
1655  *
1656  * see also pid_nr() etc in include/linux/pid.h
1657  */
1658 pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
1659                         struct pid_namespace *ns);
1660 
1661 static inline pid_t task_pid_nr(struct task_struct *tsk)
1662 {
1663         return tsk->pid;
1664 }
1665 
1666 static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
1667                                         struct pid_namespace *ns)
1668 {
1669         return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
1670 }
1671 
1672 static inline pid_t task_pid_vnr(struct task_struct *tsk)
1673 {
1674         return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
1675 }
1676 
1677 
1678 static inline pid_t task_tgid_nr(struct task_struct *tsk)
1679 {
1680         return tsk->tgid;
1681 }
1682 
1683 pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
1684 
1685 static inline pid_t task_tgid_vnr(struct task_struct *tsk)
1686 {
1687         return pid_vnr(task_tgid(tsk));
1688 }
1689 
1690 
1691 static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
1692                                         struct pid_namespace *ns)
1693 {
1694         return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
1695 }
1696 
1697 static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
1698 {
1699         return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
1700 }
1701 
1702 
1703 static inline pid_t task_session_nr_ns(struct task_struct *tsk,
1704                                         struct pid_namespace *ns)
1705 {
1706         return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
1707 }
1708 
1709 static inline pid_t task_session_vnr(struct task_struct *tsk)
1710 {
1711         return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
1712 }
1713 
1714 /* obsolete, do not use */
1715 static inline pid_t task_pgrp_nr(struct task_struct *tsk)
1716 {
1717         return task_pgrp_nr_ns(tsk, &init_pid_ns);
1718 }
1719 
1720 /**
1721  * pid_alive - check that a task structure is not stale
1722  * @p: Task structure to be checked.
1723  *
1724  * Test if a process is not yet dead (at most zombie state)
1725  * If pid_alive fails, then pointers within the task structure
1726  * can be stale and must not be dereferenced.
1727  *
1728  * Return: 1 if the process is alive. 0 otherwise.
1729  */
1730 static inline int pid_alive(struct task_struct *p)
1731 {
1732         return p->pids[PIDTYPE_PID].pid != NULL;
1733 }
1734 
1735 /**
1736  * is_global_init - check if a task structure is init
1737  * @tsk: Task structure to be checked.
1738  *
1739  * Check if a task structure is the first user space task the kernel created.
1740  *
1741  * Return: 1 if the task structure is init. 0 otherwise.
1742  */
1743 static inline int is_global_init(struct task_struct *tsk)
1744 {
1745         return tsk->pid == 1;
1746 }
1747 
1748 extern struct pid *cad_pid;
1749 
1750 extern void free_task(struct task_struct *tsk);
1751 #define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)
1752 
1753 extern void __put_task_struct(struct task_struct *t);
1754 
1755 static inline void put_task_struct(struct task_struct *t)
1756 {
1757         if (atomic_dec_and_test(&t->usage))
1758                 __put_task_struct(t);
1759 }
1760 
1761 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1762 extern void task_cputime(struct task_struct *t,
1763                          cputime_t *utime, cputime_t *stime);
1764 extern void task_cputime_scaled(struct task_struct *t,
1765                                 cputime_t *utimescaled, cputime_t *stimescaled);
1766 extern cputime_t task_gtime(struct task_struct *t);
1767 #else
1768 static inline void task_cputime(struct task_struct *t,
1769                                 cputime_t *utime, cputime_t *stime)
1770 {
1771         if (utime)
1772                 *utime = t->utime;
1773         if (stime)
1774                 *stime = t->stime;
1775 }
1776 
1777 static inline void task_cputime_scaled(struct task_struct *t,
1778                                        cputime_t *utimescaled,
1779                                        cputime_t *stimescaled)
1780 {
1781         if (utimescaled)
1782                 *utimescaled = t->utimescaled;
1783         if (stimescaled)
1784                 *stimescaled = t->stimescaled;
1785 }
1786 
1787 static inline cputime_t task_gtime(struct task_struct *t)
1788 {
1789         return t->gtime;
1790 }
1791 #endif
1792 extern void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);
1793 extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);
1794 
1795 /*
1796  * Per process flags
1797  */
1798 #define PF_EXITING      0x00000004      /* getting shut down */
1799 #define PF_EXITPIDONE   0x00000008      /* pi exit done on shut down */
1800 #define PF_VCPU         0x00000010      /* I'm a virtual CPU */
1801 #define PF_WQ_WORKER    0x00000020      /* I'm a workqueue worker */
1802 #define PF_FORKNOEXEC   0x00000040      /* forked but didn't exec */
1803 #define PF_MCE_PROCESS  0x00000080      /* process policy on mce errors */
1804 #define PF_SUPERPRIV    0x00000100      /* used super-user privileges */
1805 #define PF_DUMPCORE     0x00000200      /* dumped core */
1806 #define PF_SIGNALED     0x00000400      /* killed by a signal */
1807 #define PF_MEMALLOC     0x00000800      /* Allocating memory */
1808 #define PF_NPROC_EXCEEDED 0x00001000    /* set_user noticed that RLIMIT_NPROC was exceeded */
1809 #define PF_USED_MATH    0x00002000      /* if unset the fpu must be initialized before use */
1810 #define PF_USED_ASYNC   0x00004000      /* used async_schedule*(), used by module init */
1811 #define PF_NOFREEZE     0x00008000      /* this thread should not be frozen */
1812 #define PF_FROZEN       0x00010000      /* frozen for system suspend */
1813 #define PF_FSTRANS      0x00020000      /* inside a filesystem transaction */
1814 #define PF_KSWAPD       0x00040000      /* I am kswapd */
1815 #define PF_MEMALLOC_NOIO 0x00080000     /* Allocating memory without IO involved */
1816 #define PF_LESS_THROTTLE 0x00100000     /* Throttle me less: I clean memory */
1817 #define PF_KTHREAD      0x00200000      /* I am a kernel thread */
1818 #define PF_RANDOMIZE    0x00400000      /* randomize virtual address space */
1819 #define PF_SWAPWRITE    0x00800000      /* Allowed to write to swap */
1820 #define PF_SPREAD_PAGE  0x01000000      /* Spread page cache over cpuset */
1821 #define PF_SPREAD_SLAB  0x02000000      /* Spread some slab caches over cpuset */
1822 #define PF_NO_SETAFFINITY 0x04000000    /* Userland is not allowed to meddle with cpus_allowed */
1823 #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
1824 #define PF_MEMPOLICY    0x10000000      /* Non-default NUMA mempolicy */
1825 #define PF_MUTEX_TESTER 0x20000000      /* Thread belongs to the rt mutex tester */
1826 #define PF_FREEZER_SKIP 0x40000000      /* Freezer should not count it as freezable */
1827 #define PF_SUSPEND_TASK 0x80000000      /* this thread called freeze_processes and should not be frozen */
1828 
1829 /*
1830  * Only the _current_ task can read/write to tsk->flags, but other
1831  * tasks can access tsk->flags in readonly mode for example
1832  * with tsk_used_math (like during threaded core dumping).
1833  * There is however an exception to this rule during ptrace
1834  * or during fork: the ptracer task is allowed to write to the
1835  * child->flags of its traced child (same goes for fork, the parent
1836  * can write to the child->flags), because we're guaranteed the
1837  * child is not running and in turn not changing child->flags
1838  * at the same time the parent does it.
1839  */
1840 #define clear_stopped_child_used_math(child) do { (child)->flags &= ~PF_USED_MATH; } while (0)
1841 #define set_stopped_child_used_math(child) do { (child)->flags |= PF_USED_MATH; } while (0)
1842 #define clear_used_math() clear_stopped_child_used_math(current)
1843 #define set_used_math() set_stopped_child_used_math(current)
1844 #define conditional_stopped_child_used_math(condition, child) \
1845         do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= (condition) ? PF_USED_MATH : 0; } while (0)
1846 #define conditional_used_math(condition) \
1847         conditional_stopped_child_used_math(condition, current)
1848 #define copy_to_stopped_child_used_math(child) \
1849         do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= current->flags & PF_USED_MATH; } while (0)
1850 /* NOTE: this will return 0 or PF_USED_MATH, it will never return 1 */
1851 #define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
1852 #define used_math() tsk_used_math(current)
1853 
1854 /* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags */
1855 static inline gfp_t memalloc_noio_flags(gfp_t flags)
1856 {
1857         if (unlikely(current->flags & PF_MEMALLOC_NOIO))
1858                 flags &= ~__GFP_IO;
1859         return flags;
1860 }
1861 
1862 static inline unsigned int memalloc_noio_save(void)
1863 {
1864         unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
1865         current->flags |= PF_MEMALLOC_NOIO;
1866         return flags;
1867 }
1868 
1869 static inline void memalloc_noio_restore(unsigned int flags)
1870 {
1871         current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
1872 }
1873 
1874 /*
1875  * task->jobctl flags
1876  */
1877 #define JOBCTL_STOP_SIGMASK     0xffff  /* signr of the last group stop */
1878 
1879 #define JOBCTL_STOP_DEQUEUED_BIT 16     /* stop signal dequeued */
1880 #define JOBCTL_STOP_PENDING_BIT 17      /* task should stop for group stop */
1881 #define JOBCTL_STOP_CONSUME_BIT 18      /* consume group stop count */
1882 #define JOBCTL_TRAP_STOP_BIT    19      /* trap for STOP */
1883 #define JOBCTL_TRAP_NOTIFY_BIT  20      /* trap for NOTIFY */
1884 #define JOBCTL_TRAPPING_BIT     21      /* switching to TRACED */
1885 #define JOBCTL_LISTENING_BIT    22      /* ptracer is listening for events */
1886 
1887 #define JOBCTL_STOP_DEQUEUED    (1 << JOBCTL_STOP_DEQUEUED_BIT)
1888 #define JOBCTL_STOP_PENDING     (1 << JOBCTL_STOP_PENDING_BIT)
1889 #define JOBCTL_STOP_CONSUME     (1 << JOBCTL_STOP_CONSUME_BIT)
1890 #define JOBCTL_TRAP_STOP        (1 << JOBCTL_TRAP_STOP_BIT)
1891 #define JOBCTL_TRAP_NOTIFY      (1 << JOBCTL_TRAP_NOTIFY_BIT)
1892 #define JOBCTL_TRAPPING         (1 << JOBCTL_TRAPPING_BIT)
1893 #define JOBCTL_LISTENING        (1 << JOBCTL_LISTENING_BIT)
1894 
1895 #define JOBCTL_TRAP_MASK        (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
1896 #define JOBCTL_PENDING_MASK     (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)
1897 
1898 extern bool task_set_jobctl_pending(struct task_struct *task,
1899                                     unsigned int mask);
1900 extern void task_clear_jobctl_trapping(struct task_struct *task);
1901 extern void task_clear_jobctl_pending(struct task_struct *task,
1902                                       unsigned int mask);
1903 
1904 #ifdef CONFIG_PREEMPT_RCU
1905 
1906 #define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
1907 #define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */
1908 
1909 static inline void rcu_copy_process(struct task_struct *p)
1910 {
1911         p->rcu_read_lock_nesting = 0;
1912         p->rcu_read_unlock_special = 0;
1913 #ifdef CONFIG_TREE_PREEMPT_RCU
1914         p->rcu_blocked_node = NULL;
1915 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
1916 #ifdef CONFIG_RCU_BOOST
1917         p->rcu_boost_mutex = NULL;
1918 #endif /* #ifdef CONFIG_RCU_BOOST */
1919         INIT_LIST_HEAD(&p->rcu_node_entry);
1920 }
1921 
1922 #else
1923 
1924 static inline void rcu_copy_process(struct task_struct *p)
1925 {
1926 }
1927 
1928 #endif
1929 
1930 static inline void tsk_restore_flags(struct task_struct *task,
1931                                 unsigned long orig_flags, unsigned long flags)
1932 {
1933         task->flags &= ~flags;
1934         task->flags |= orig_flags & flags;
1935 }
1936 
1937 #ifdef CONFIG_SMP
1938 extern void do_set_cpus_allowed(struct task_struct *p,
1939                                const struct cpumask *new_mask);
1940 
1941 extern int set_cpus_allowed_ptr(struct task_struct *p,
1942                                 const struct cpumask *new_mask);
1943 #else
1944 static inline void do_set_cpus_allowed(struct task_struct *p,
1945                                       const struct cpumask *new_mask)
1946 {
1947 }
1948 static inline int set_cpus_allowed_ptr(struct task_struct *p,
1949                                        const struct cpumask *new_mask)
1950 {
1951         if (!cpumask_test_cpu(0, new_mask))
1952                 return -EINVAL;
1953         return 0;
1954 }
1955 #endif
1956 
1957 #ifdef CONFIG_NO_HZ_COMMON
1958 void calc_load_enter_idle(void);
1959 void calc_load_exit_idle(void);
1960 #else
1961 static inline void calc_load_enter_idle(void) { }
1962 static inline void calc_load_exit_idle(void) { }
1963 #endif /* CONFIG_NO_HZ_COMMON */
1964 
1965 #ifndef CONFIG_CPUMASK_OFFSTACK
1966 static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
1967 {
1968         return set_cpus_allowed_ptr(p, &new_mask);
1969 }
1970 #endif
1971 
1972 /*
1973  * Do not use outside of architecture code which knows its limitations.
1974  *
1975  * sched_clock() has no promise of monotonicity or bounded drift between
1976  * CPUs, use (which you should not) requires disabling IRQs.
1977  *
1978  * Please use one of the three interfaces below.
1979  */
1980 extern unsigned long long notrace sched_clock(void);
1981 /*
1982  * See the comment in kernel/sched/clock.c
1983  */
1984 extern u64 cpu_clock(int cpu);
1985 extern u64 local_clock(void);
1986 extern u64 sched_clock_cpu(int cpu);
1987 
1988 
1989 extern void sched_clock_init(void);
1990 
1991 #ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
1992 static inline void sched_clock_tick(void)
1993 {
1994 }
1995 
1996 static inline void sched_clock_idle_sleep_event(void)
1997 {
1998 }
1999 
2000 static inline void sched_clock_idle_wakeup_event(u64 delta_ns)
2001 {
2002 }
2003 #else
2004 /*
2005  * Architectures can set this to 1 if they have specified
2006  * CONFIG_HAVE_UNSTABLE_SCHED_CLOCK in their arch Kconfig,
2007  * but then during bootup it turns out that sched_clock()
2008  * is reliable after all:
2009  */
2010 extern int sched_clock_stable(void);
2011 extern void set_sched_clock_stable(void);
2012 extern void clear_sched_clock_stable(void);
2013 
2014 extern void sched_clock_tick(void);
2015 extern void sched_clock_idle_sleep_event(void);
2016 extern void sched_clock_idle_wakeup_event(u64 delta_ns);
2017 #endif
2018 
2019 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
2020 /*
2021  * An i/f to runtime opt-in for irq time accounting based off of sched_clock.
2022  * The reason for this explicit opt-in is not to have perf penalty with
2023  * slow sched_clocks.
2024  */
2025 extern void enable_sched_clock_irqtime(void);
2026 extern void disable_sched_clock_irqtime(void);
2027 #else
2028 static inline void enable_sched_clock_irqtime(void) {}
2029 static inline void disable_sched_clock_irqtime(void) {}
2030 #endif
2031 
2032 extern unsigned long long
2033 task_sched_runtime(struct task_struct *task);
2034 
2035 /* sched_exec is called by processes performing an exec */
2036 #ifdef CONFIG_SMP
2037 extern void sched_exec(void);
2038 #else
2039 #define sched_exec()   {}
2040 #endif
2041 
2042 extern void sched_clock_idle_sleep_event(void);
2043 extern void sched_clock_idle_wakeup_event(u64 delta_ns);
2044 
2045 #ifdef CONFIG_HOTPLUG_CPU
2046 extern void idle_task_exit(void);
2047 #else
2048 static inline void idle_task_exit(void) {}
2049 #endif
2050 
2051 #if defined(CONFIG_NO_HZ_COMMON) && defined(CONFIG_SMP)
2052 extern void wake_up_nohz_cpu(int cpu);
2053 #else
2054 static inline void wake_up_nohz_cpu(int cpu) { }
2055 #endif
2056 
2057 #ifdef CONFIG_NO_HZ_FULL
2058 extern bool sched_can_stop_tick(void);
2059 extern u64 scheduler_tick_max_deferment(void);
2060 #else
2061 static inline bool sched_can_stop_tick(void) { return false; }
2062 #endif
2063 
2064 #ifdef CONFIG_SCHED_AUTOGROUP
2065 extern void sched_autogroup_create_attach(struct task_struct *p);
2066 extern void sched_autogroup_detach(struct task_struct *p);
2067 extern void sched_autogroup_fork(struct signal_struct *sig);
2068 extern void sched_autogroup_exit(struct signal_struct *sig);
2069 #ifdef CONFIG_PROC_FS
2070 extern void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m);
2071 extern int proc_sched_autogroup_set_nice(struct task_struct *p, int nice);
2072 #endif
2073 #else
2074 static inline void sched_autogroup_create_attach(struct task_struct *p) { }
2075 static inline void sched_autogroup_detach(struct task_struct *p) { }
2076 static inline void sched_autogroup_fork(struct signal_struct *sig) { }
2077 static inline void sched_autogroup_exit(struct signal_struct *sig) { }
2078 #endif
2079 
2080 extern bool yield_to(struct task_struct *p, bool preempt);
2081 extern void set_user_nice(struct task_struct *p, long nice);
2082 extern int task_prio(const struct task_struct *p);
2083 extern int task_nice(const struct task_struct *p);
2084 extern int can_nice(const struct task_struct *p, const int nice);
2085 extern int task_curr(const struct task_struct *p);
2086 extern int idle_cpu(int cpu);
2087 extern int sched_setscheduler(struct task_struct *, int,
2088                               const struct sched_param *);
2089 extern int sched_setscheduler_nocheck(struct task_struct *, int,
2090                                       const struct sched_param *);
2091 extern int sched_setattr(struct task_struct *,
2092                          const struct sched_attr *);
2093 extern struct task_struct *idle_task(int cpu);
2094 /**
2095  * is_idle_task - is the specified task an idle task?
2096  * @p: the task in question.
2097  *
2098  * Return: 1 if @p is an idle task. 0 otherwise.
2099  */
2100 static inline bool is_idle_task(const struct task_struct *p)
2101 {
2102         return p->pid == 0;
2103 }
2104 extern struct task_struct *curr_task(int cpu);
2105 extern void set_curr_task(int cpu, struct task_struct *p);
2106 
2107 void yield(void);
2108 
2109 /*
2110  * The default (Linux) execution domain.
2111  */
2112 extern struct exec_domain       default_exec_domain;
2113 
2114 union thread_union {
2115         struct thread_info thread_info;
2116         unsigned long stack[THREAD_SIZE/sizeof(long)];
2117 };
2118 
2119 #ifndef __HAVE_ARCH_KSTACK_END
2120 static inline int kstack_end(void *addr)
2121 {
2122         /* Reliable end of stack detection:
2123          * Some APM bios versions misalign the stack
2124          */
2125         return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
2126 }
2127 #endif
2128 
2129 extern union thread_union init_thread_union;
2130 extern struct task_struct init_task;
2131 
2132 extern struct   mm_struct init_mm;
2133 
2134 extern struct pid_namespace init_pid_ns;
2135 
2136 /*
2137  * find a task by one of its numerical ids
2138  *
2139  * find_task_by_pid_ns():
2140  *      finds a task by its pid in the specified namespace
2141  * find_task_by_vpid():
2142  *      finds a task by its virtual pid
2143  *
2144  * see also find_vpid() etc in include/linux/pid.h
2145  */
2146 
2147 extern struct task_struct *find_task_by_vpid(pid_t nr);
2148 extern struct task_struct *find_task_by_pid_ns(pid_t nr,
2149                 struct pid_namespace *ns);
2150 
2151 /* per-UID process charging. */
2152 extern struct user_struct * alloc_uid(kuid_t);
2153 static inline struct user_struct *get_uid(struct user_struct *u)
2154 {
2155         atomic_inc(&u->__count);
2156         return u;
2157 }
2158 extern void free_uid(struct user_struct *);
2159 
2160 #include <asm/current.h>
2161 
2162 extern void xtime_update(unsigned long ticks);
2163 
2164 extern int wake_up_state(struct task_struct *tsk, unsigned int state);
2165 extern int wake_up_process(struct task_struct *tsk);
2166 extern void wake_up_new_task(struct task_struct *tsk);
2167 #ifdef CONFIG_SMP
2168  extern void kick_process(struct task_struct *tsk);
2169 #else
2170  static inline void kick_process(struct task_struct *tsk) { }
2171 #endif
2172 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
2173 extern void sched_dead(struct task_struct *p);
2174 
2175 extern void proc_caches_init(void);
2176 extern void flush_signals(struct task_struct *);
2177 extern void __flush_signals(struct task_struct *);
2178 extern void ignore_signals(struct task_struct *);
2179 extern void flush_signal_handlers(struct task_struct *, int force_default);
2180 extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
2181 
2182 static inline int dequeue_signal_lock(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
2183 {
2184         unsigned long flags;
2185         int ret;
2186 
2187         spin_lock_irqsave(&tsk->sighand->siglock, flags);
2188         ret = dequeue_signal(tsk, mask, info);
2189         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
2190 
2191         return ret;
2192 }
2193 
2194 extern void block_all_signals(int (*notifier)(void *priv), void *priv,
2195                               sigset_t *mask);
2196 extern void unblock_all_signals(void);
2197 extern void release_task(struct task_struct * p);
2198 extern int send_sig_info(int, struct siginfo *, struct task_struct *);
2199 extern int force_sigsegv(int, struct task_struct *);
2200 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
2201 extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
2202 extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
2203 extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
2204                                 const struct cred *, u32);
2205 extern int kill_pgrp(struct pid *pid, int sig, int priv);
2206 extern int kill_pid(struct pid *pid, int sig, int priv);
2207 extern int kill_proc_info(int, struct siginfo *, pid_t);
2208 extern __must_check bool do_notify_parent(struct task_struct *, int);
2209 extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
2210 extern void force_sig(int, struct task_struct *);
2211 extern int send_sig(int, struct task_struct *, int);
2212 extern int zap_other_threads(struct task_struct *p);
2213 extern struct sigqueue *sigqueue_alloc(void);
2214 extern void sigqueue_free(struct sigqueue *);
2215 extern int send_sigqueue(struct sigqueue *,  struct task_struct *, int group);
2216 extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);
2217 
2218 static inline void restore_saved_sigmask(void)
2219 {
2220         if (test_and_clear_restore_sigmask())
2221                 __set_current_blocked(&current->saved_sigmask);
2222 }
2223 
2224 static inline sigset_t *sigmask_to_save(void)
2225 {
2226         sigset_t *res = &current->blocked;
2227         if (unlikely(test_restore_sigmask()))
2228                 res = &current->saved_sigmask;
2229         return res;
2230 }
2231 
2232 static inline int kill_cad_pid(int sig, int priv)
2233 {
2234         return kill_pid(cad_pid, sig, priv);
2235 }
2236 
2237 /* These can be the second arg to send_sig_info/send_group_sig_info.  */
2238 #define SEND_SIG_NOINFO ((struct siginfo *) 0)
2239 #define SEND_SIG_PRIV   ((struct siginfo *) 1)
2240 #define SEND_SIG_FORCED ((struct siginfo *) 2)
2241 
2242 /*
2243  * True if we are on the alternate signal stack.
2244  */
2245 static inline int on_sig_stack(unsigned long sp)
2246 {
2247 #ifdef CONFIG_STACK_GROWSUP
2248         return sp >= current->sas_ss_sp &&
2249                 sp - current->sas_ss_sp < current->sas_ss_size;
2250 #else
2251         return sp > current->sas_ss_sp &&
2252                 sp - current->sas_ss_sp <= current->sas_ss_size;
2253 #endif
2254 }
2255 
2256 static inline int sas_ss_flags(unsigned long sp)
2257 {
2258         return (current->sas_ss_size == 0 ? SS_DISABLE
2259                 : on_sig_stack(sp) ? SS_ONSTACK : 0);
2260 }
2261 
2262 static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
2263 {
2264         if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
2265 #ifdef CONFIG_STACK_GROWSUP
2266                 return current->sas_ss_sp;
2267 #else
2268                 return current->sas_ss_sp + current->sas_ss_size;
2269 #endif
2270         return sp;
2271 }
2272 
2273 /*
2274  * Routines for handling mm_structs
2275  */
2276 extern struct mm_struct * mm_alloc(void);
2277 
2278 /* mmdrop drops the mm and the page tables */
2279 extern void __mmdrop(struct mm_struct *);
2280 static inline void mmdrop(struct mm_struct * mm)
2281 {
2282         if (unlikely(atomic_dec_and_test(&mm->mm_count)))
2283                 __mmdrop(mm);
2284 }
2285 
2286 /* mmput gets rid of the mappings and all user-space */
2287 extern void mmput(struct mm_struct *);
2288 /* Grab a reference to a task's mm, if it is not already going away */
2289 extern struct mm_struct *get_task_mm(struct task_struct *task);
2290 /*
2291  * Grab a reference to a task's mm, if it is not already going away
2292  * and ptrace_may_access with the mode parameter passed to it
2293  * succeeds.
2294  */
2295 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
2296 /* Remove the current tasks stale references to the old mm_struct */
2297 extern void mm_release(struct task_struct *, struct mm_struct *);
2298 
2299 extern int copy_thread(unsigned long, unsigned long, unsigned long,
2300                         struct task_struct *);
2301 extern void flush_thread(void);
2302 extern void exit_thread(void);
2303 
2304 extern void exit_files(struct task_struct *);
2305 extern void __cleanup_sighand(struct sighand_struct *);
2306 
2307 extern void exit_itimers(struct signal_struct *);
2308 extern void flush_itimer_signals(void);
2309 
2310 extern void do_group_exit(int);
2311 
2312 extern int allow_signal(int);
2313 extern int disallow_signal(int);
2314 
2315 extern int do_execve(struct filename *,
2316                      const char __user * const __user *,
2317                      const char __user * const __user *);
2318 extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
2319 struct task_struct *fork_idle(int);
2320 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
2321 
2322 extern void set_task_comm(struct task_struct *tsk, char *from);
2323 extern char *get_task_comm(char *to, struct task_struct *tsk);
2324 
2325 #ifdef CONFIG_SMP
2326 void scheduler_ipi(void);
2327 extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
2328 #else
2329 static inline void scheduler_ipi(void) { }
2330 static inline unsigned long wait_task_inactive(struct task_struct *p,
2331                                                long match_state)
2332 {
2333         return 1;
2334 }
2335 #endif
2336 
2337 #define next_task(p) \
2338         list_entry_rcu((p)->tasks.next, struct task_struct, tasks)
2339 
2340 #define for_each_process(p) \
2341         for (p = &init_task ; (p = next_task(p)) != &init_task ; )
2342 
2343 extern bool current_is_single_threaded(void);
2344 
2345 /*
2346  * Careful: do_each_thread/while_each_thread is a double loop so
2347  *          'break' will not work as expected - use goto instead.
2348  */
2349 #define do_each_thread(g, t) \
2350         for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do
2351 
2352 #define while_each_thread(g, t) \
2353         while ((t = next_thread(t)) != g)
2354 
2355 #define __for_each_thread(signal, t)    \
2356         list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)
2357 
2358 #define for_each_thread(p, t)           \
2359         __for_each_thread((p)->signal, t)
2360 
2361 /* Careful: this is a double loop, 'break' won't work as expected. */
2362 #define for_each_process_thread(p, t)   \
2363         for_each_process(p) for_each_thread(p, t)
2364 
2365 static inline int get_nr_threads(struct task_struct *tsk)
2366 {
2367         return tsk->signal->nr_threads;
2368 }
2369 
2370 static inline bool thread_group_leader(struct task_struct *p)
2371 {
2372         return p->exit_signal >= 0;
2373 }
2374 
2375 /* Do to the insanities of de_thread it is possible for a process
2376  * to have the pid of the thread group leader without actually being
2377  * the thread group leader.  For iteration through the pids in proc
2378  * all we care about is that we have a task with the appropriate
2379  * pid, we don't actually care if we have the right task.
2380  */
2381 static inline bool has_group_leader_pid(struct task_struct *p)
2382 {
2383         return task_pid(p) == p->signal->leader_pid;
2384 }
2385 
2386 static inline
2387 bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
2388 {
2389         return p1->signal == p2->signal;
2390 }
2391 
2392 static inline struct task_struct *next_thread(const struct task_struct *p)
2393 {
2394         return list_entry_rcu(p->thread_group.next,
2395                               struct task_struct, thread_group);
2396 }
2397 
2398 static inline int thread_group_empty(struct task_struct *p)
2399 {
2400         return list_empty(&p->thread_group);
2401 }
2402 
2403 #define delay_group_leader(p) \
2404                 (thread_group_leader(p) && !thread_group_empty(p))
2405 
2406 /*
2407  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
2408  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
2409  * pins the final release of task.io_context.  Also protects ->cpuset and
2410  * ->cgroup.subsys[]. And ->vfork_done.
2411  *
2412  * Nests both inside and outside of read_lock(&tasklist_lock).
2413  * It must not be nested with write_lock_irq(&tasklist_lock),
2414  * neither inside nor outside.
2415  */
2416 static inline void task_lock(struct task_struct *p)
2417 {
2418         spin_lock(&p->alloc_lock);
2419 }
2420 
2421 static inline void task_unlock(struct task_struct *p)
2422 {
2423         spin_unlock(&p->alloc_lock);
2424 }
2425 
2426 extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
2427                                                         unsigned long *flags);
2428 
2429 static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
2430                                                        unsigned long *flags)
2431 {
2432         struct sighand_struct *ret;
2433 
2434         ret = __lock_task_sighand(tsk, flags);
2435         (void)__cond_lock(&tsk->sighand->siglock, ret);
2436         return ret;
2437 }
2438 
2439 static inline void unlock_task_sighand(struct task_struct *tsk,
2440                                                 unsigned long *flags)
2441 {
2442         spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
2443 }
2444 
2445 #ifdef CONFIG_CGROUPS
2446 static inline void threadgroup_change_begin(struct task_struct *tsk)
2447 {
2448         down_read(&tsk->signal->group_rwsem);
2449 }
2450 static inline void threadgroup_change_end(struct task_struct *tsk)
2451 {
2452         up_read(&tsk->signal->group_rwsem);
2453 }
2454 
2455 /**
2456  * threadgroup_lock - lock threadgroup
2457  * @tsk: member task of the threadgroup to lock
2458  *
2459  * Lock the threadgroup @tsk belongs to.  No new task is allowed to enter
2460  * and member tasks aren't allowed to exit (as indicated by PF_EXITING) or
2461  * change ->group_leader/pid.  This is useful for cases where the threadgroup
2462  * needs to stay stable across blockable operations.
2463  *
2464  * fork and exit paths explicitly call threadgroup_change_{begin|end}() for
2465  * synchronization.  While held, no new task will be added to threadgroup
2466  * and no existing live task will have its PF_EXITING set.
2467  *
2468  * de_thread() does threadgroup_change_{begin|end}() when a non-leader
2469  * sub-thread becomes a new leader.
2470  */
2471 static inline void threadgroup_lock(struct task_struct *tsk)
2472 {
2473         down_write(&tsk->signal->group_rwsem);
2474 }
2475 
2476 /**
2477  * threadgroup_unlock - unlock threadgroup
2478  * @tsk: member task of the threadgroup to unlock
2479  *
2480  * Reverse threadgroup_lock().
2481  */
2482 static inline void threadgroup_unlock(struct task_struct *tsk)
2483 {
2484         up_write(&tsk->signal->group_rwsem);
2485 }
2486 #else
2487 static inline void threadgroup_change_begin(struct task_struct *tsk) {}
2488 static inline void threadgroup_change_end(struct task_struct *tsk) {}
2489 static inline void threadgroup_lock(struct task_struct *tsk) {}
2490 static inline void threadgroup_unlock(struct task_struct *tsk) {}
2491 #endif
2492 
2493 #ifndef __HAVE_THREAD_FUNCTIONS
2494 
2495 #define task_thread_info(task)  ((struct thread_info *)(task)->stack)
2496 #define task_stack_page(task)   ((task)->stack)
2497 
2498 static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
2499 {
2500         *task_thread_info(p) = *task_thread_info(org);
2501         task_thread_info(p)->task = p;
2502 }
2503 
2504 static inline unsigned long *end_of_stack(struct task_struct *p)
2505 {
2506         return (unsigned long *)(task_thread_info(p) + 1);
2507 }
2508 
2509 #endif
2510 
2511 static inline int object_is_on_stack(void *obj)
2512 {
2513         void *stack = task_stack_page(current);
2514 
2515         return (obj >= stack) && (obj < (stack + THREAD_SIZE));
2516 }
2517 
2518 extern void thread_info_cache_init(void);
2519 
2520 #ifdef CONFIG_DEBUG_STACK_USAGE
2521 static inline unsigned long stack_not_used(struct task_struct *p)
2522 {
2523         unsigned long *n = end_of_stack(p);
2524 
2525         do {    /* Skip over canary */
2526                 n++;
2527         } while (!*n);
2528 
2529         return (unsigned long)n - (unsigned long)end_of_stack(p);
2530 }
2531 #endif
2532 
2533 /* set thread flags in other task's structures
2534  * - see asm/thread_info.h for TIF_xxxx flags available
2535  */
2536 static inline void set_tsk_thread_flag(struct task_struct *tsk, int flag)
2537 {
2538         set_ti_thread_flag(task_thread_info(tsk), flag);
2539 }
2540 
2541 static inline void clear_tsk_thread_flag(struct task_struct *tsk, int flag)
2542 {
2543         clear_ti_thread_flag(task_thread_info(tsk), flag);
2544 }
2545 
2546 static inline int test_and_set_tsk_thread_flag(struct task_struct *tsk, int flag)
2547 {
2548         return test_and_set_ti_thread_flag(task_thread_info(tsk), flag);
2549 }
2550 
2551 static inline int test_and_clear_tsk_thread_flag(struct task_struct *tsk, int flag)
2552 {
2553         return test_and_clear_ti_thread_flag(task_thread_info(tsk), flag);
2554 }
2555 
2556 static inline int test_tsk_thread_flag(struct task_struct *tsk, int flag)
2557 {
2558         return test_ti_thread_flag(task_thread_info(tsk), flag);
2559 }
2560 
2561 static inline void set_tsk_need_resched(struct task_struct *tsk)
2562 {
2563         set_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
2564 }
2565 
2566 static inline void clear_tsk_need_resched(struct task_struct *tsk)
2567 {
2568         clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
2569 }
2570 
2571 static inline int test_tsk_need_resched(struct task_struct *tsk)
2572 {
2573         return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
2574 }
2575 
2576 static inline int restart_syscall(void)
2577 {
2578         set_tsk_thread_flag(current, TIF_SIGPENDING);
2579         return -ERESTARTNOINTR;
2580 }
2581 
2582 static inline int signal_pending(struct task_struct *p)
2583 {
2584         return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
2585 }
2586 
2587 static inline int __fatal_signal_pending(struct task_struct *p)
2588 {
2589         return unlikely(sigismember(&p->pending.signal, SIGKILL));
2590 }
2591 
2592 static inline int fatal_signal_pending(struct task_struct *p)
2593 {
2594         return signal_pending(p) && __fatal_signal_pending(p);
2595 }
2596 
2597 static inline int signal_pending_state(long state, struct task_struct *p)
2598 {
2599         if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
2600                 return 0;
2601         if (!signal_pending(p))
2602                 return 0;
2603 
2604         return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
2605 }
2606 
2607 /*
2608  * cond_resched() and cond_resched_lock(): latency reduction via
2609  * explicit rescheduling in places that are safe. The return
2610  * value indicates whether a reschedule was done in fact.
2611  * cond_resched_lock() will drop the spinlock before scheduling,
2612  * cond_resched_softirq() will enable bhs before scheduling.
2613  */
2614 extern int _cond_resched(void);
2615 
2616 #define cond_resched() ({                       \
2617         __might_sleep(__FILE__, __LINE__, 0);   \
2618         _cond_resched();                        \
2619 })
2620 
2621 extern int __cond_resched_lock(spinlock_t *lock);
2622 
2623 #ifdef CONFIG_PREEMPT_COUNT
2624 #define PREEMPT_LOCK_OFFSET     PREEMPT_OFFSET
2625 #else
2626 #define PREEMPT_LOCK_OFFSET     0
2627 #endif
2628 
2629 #define cond_resched_lock(lock) ({                              \
2630         __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
2631         __cond_resched_lock(lock);                              \
2632 })
2633 
2634 extern int __cond_resched_softirq(void);
2635 
2636 #define cond_resched_softirq() ({                                       \
2637         __might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET);      \
2638         __cond_resched_softirq();                                       \
2639 })
2640 
2641 static inline void cond_resched_rcu(void)
2642 {
2643 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
2644         rcu_read_unlock();
2645         cond_resched();
2646         rcu_read_lock();
2647 #endif
2648 }
2649 
2650 /*
2651  * Does a critical section need to be broken due to another
2652  * task waiting?: (technically does not depend on CONFIG_PREEMPT,
2653  * but a general need for low latency)
2654  */
2655 static inline int spin_needbreak(spinlock_t *lock)
2656 {
2657 #ifdef CONFIG_PREEMPT
2658         return spin_is_contended(lock);
2659 #else
2660         return 0;
2661 #endif
2662 }
2663 
2664 /*
2665  * Idle thread specific functions to determine the need_resched
2666  * polling state. We have two versions, one based on TS_POLLING in
2667  * thread_info.status and one based on TIF_POLLING_NRFLAG in
2668  * thread_info.flags
2669  */
2670 #ifdef TS_POLLING
2671 static inline int tsk_is_polling(struct task_struct *p)
2672 {
2673         return task_thread_info(p)->status & TS_POLLING;
2674 }
2675 static inline void __current_set_polling(void)
2676 {
2677         current_thread_info()->status |= TS_POLLING;
2678 }
2679 
2680 static inline bool __must_check current_set_polling_and_test(void)
2681 {
2682         __current_set_polling();
2683 
2684         /*
2685          * Polling state must be visible before we test NEED_RESCHED,
2686          * paired by resched_task()
2687          */
2688         smp_mb();
2689 
2690         return unlikely(tif_need_resched());
2691 }
2692 
2693 static inline void __current_clr_polling(void)
2694 {
2695         current_thread_info()->status &= ~TS_POLLING;
2696 }
2697 
2698 static inline bool __must_check current_clr_polling_and_test(void)
2699 {
2700         __current_clr_polling();
2701 
2702         /*
2703          * Polling state must be visible before we test NEED_RESCHED,
2704          * paired by resched_task()
2705          */
2706         smp_mb();
2707 
2708         return unlikely(tif_need_resched());
2709 }
2710 #elif defined(TIF_POLLING_NRFLAG)
2711 static inline int tsk_is_polling(struct task_struct *p)
2712 {
2713         return test_tsk_thread_flag(p, TIF_POLLING_NRFLAG);
2714 }
2715 
2716 static inline void __current_set_polling(void)
2717 {
2718         set_thread_flag(TIF_POLLING_NRFLAG);
2719 }
2720 
2721 static inline bool __must_check current_set_polling_and_test(void)
2722 {
2723         __current_set_polling();
2724 
2725         /*
2726          * Polling state must be visible before we test NEED_RESCHED,
2727          * paired by resched_task()
2728          *
2729          * XXX: assumes set/clear bit are identical barrier wise.
2730          */
2731         smp_mb__after_clear_bit();
2732 
2733         return unlikely(tif_need_resched());
2734 }
2735 
2736 static inline void __current_clr_polling(void)
2737 {
2738         clear_thread_flag(TIF_POLLING_NRFLAG);
2739 }
2740 
2741 static inline bool __must_check current_clr_polling_and_test(void)
2742 {
2743         __current_clr_polling();
2744 
2745         /*
2746          * Polling state must be visible before we test NEED_RESCHED,
2747          * paired by resched_task()
2748          */
2749         smp_mb__after_clear_bit();
2750 
2751         return unlikely(tif_need_resched());
2752 }
2753 
2754 #else
2755 static inline int tsk_is_polling(struct task_struct *p) { return 0; }
2756 static inline void __current_set_polling(void) { }
2757 static inline void __current_clr_polling(void) { }
2758 
2759 static inline bool __must_check current_set_polling_and_test(void)
2760 {
2761         return unlikely(tif_need_resched());
2762 }
2763 static inline bool __must_check current_clr_polling_and_test(void)
2764 {
2765         return unlikely(tif_need_resched());
2766 }
2767 #endif
2768 
2769 static inline void current_clr_polling(void)
2770 {
2771         __current_clr_polling();
2772 
2773         /*
2774          * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
2775          * Once the bit is cleared, we'll get IPIs with every new
2776          * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
2777          * fold.
2778          */
2779         smp_mb(); /* paired with resched_task() */
2780 
2781         preempt_fold_need_resched();
2782 }
2783 
2784 static __always_inline bool need_resched(void)
2785 {
2786         return unlikely(tif_need_resched());
2787 }
2788 
2789 /*
2790  * Thread group CPU time accounting.
2791  */
2792 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
2793 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);
2794 
2795 static inline void thread_group_cputime_init(struct signal_struct *sig)
2796 {
2797         raw_spin_lock_init(&sig->cputimer.lock);
2798 }
2799 
2800 /*
2801  * Reevaluate whether the task has signals pending delivery.
2802  * Wake the task if so.
2803  * This is required every time the blocked sigset_t changes.
2804  * callers must hold sighand->siglock.
2805  */
2806 extern void recalc_sigpending_and_wake(struct task_struct *t);
2807 extern void recalc_sigpending(void);
2808 
2809 extern void signal_wake_up_state(struct task_struct *t, unsigned int state);
2810 
2811 static inline void signal_wake_up(struct task_struct *t, bool resume)
2812 {
2813         signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
2814 }
2815 static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
2816 {
2817         signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
2818 }
2819 
2820 /*
2821  * Wrappers for p->thread_info->cpu access. No-op on UP.
2822  */
2823 #ifdef CONFIG_SMP
2824 
2825 static inline unsigned int task_cpu(const struct task_struct *p)
2826 {
2827         return task_thread_info(p)->cpu;
2828 }
2829 
2830 static inline int task_node(const struct task_struct *p)
2831 {
2832         return cpu_to_node(task_cpu(p));
2833 }
2834 
2835 extern void set_task_cpu(struct task_struct *p, unsigned int cpu);
2836 
2837 #else
2838 
2839 static inline unsigned int task_cpu(const struct task_struct *p)
2840 {
2841         return 0;
2842 }
2843 
2844 static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
2845 {
2846 }
2847 
2848 #endif /* CONFIG_SMP */
2849 
2850 extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);
2851 extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
2852 
2853 #ifdef CONFIG_CGROUP_SCHED
2854 extern struct task_group root_task_group;
2855 #endif /* CONFIG_CGROUP_SCHED */
2856 
2857 extern int task_can_switch_user(struct user_struct *up,
2858                                         struct task_struct *tsk);
2859 
2860 #ifdef CONFIG_TASK_XACCT
2861 static inline void add_rchar(struct task_struct *tsk, ssize_t amt)
2862 {
2863         tsk->ioac.rchar += amt;
2864 }
2865 
2866 static inline void add_wchar(struct task_struct *tsk, ssize_t amt)
2867 {
2868         tsk->ioac.wchar += amt;
2869 }
2870 
2871 static inline void inc_syscr(struct task_struct *tsk)
2872 {
2873         tsk->ioac.syscr++;
2874 }
2875 
2876 static inline void inc_syscw(struct task_struct *tsk)
2877 {
2878         tsk->ioac.syscw++;
2879 }
2880 #else
2881 static inline void add_rchar(struct task_struct *tsk, ssize_t amt)
2882 {
2883 }
2884 
2885 static inline void add_wchar(struct task_struct *tsk, ssize_t amt)
2886 {
2887 }
2888 
2889 static inline void inc_syscr(struct task_struct *tsk)
2890 {
2891 }
2892 
2893 static inline void inc_syscw(struct task_struct *tsk)
2894 {
2895 }
2896 #endif
2897 
2898 #ifndef TASK_SIZE_OF
2899 #define TASK_SIZE_OF(tsk)       TASK_SIZE
2900 #endif
2901 
2902 #ifdef CONFIG_MM_OWNER
2903 extern void mm_update_next_owner(struct mm_struct *mm);
2904 extern void mm_init_owner(struct mm_struct *mm, struct task_struct *p);
2905 #else
2906 static inline void mm_update_next_owner(struct mm_struct *mm)
2907 {
2908 }
2909 
2910 static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
2911 {
2912 }
2913 #endif /* CONFIG_MM_OWNER */
2914 
2915 static inline unsigned long task_rlimit(const struct task_struct *tsk,
2916                 unsigned int limit)
2917 {
2918         return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_cur);
2919 }
2920 
2921 static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
2922                 unsigned int limit)
2923 {
2924         return ACCESS_ONCE(tsk->signal->rlim[limit].rlim_max);
2925 }
2926 
2927 static inline unsigned long rlimit(unsigned int limit)
2928 {
2929         return task_rlimit(current, limit);
2930 }
2931 
2932 static inline unsigned long rlimit_max(unsigned int limit)
2933 {
2934         return task_rlimit_max(current, limit);
2935 }
2936 
2937 #endif
2938 

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