Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/include/linux/kernel.h

  1 #ifndef _LINUX_KERNEL_H
  2 #define _LINUX_KERNEL_H
  3 
  4 
  5 #include <stdarg.h>
  6 #include <linux/linkage.h>
  7 #include <linux/stddef.h>
  8 #include <linux/types.h>
  9 #include <linux/compiler.h>
 10 #include <linux/bitops.h>
 11 #include <linux/log2.h>
 12 #include <linux/typecheck.h>
 13 #include <linux/printk.h>
 14 #include <linux/dynamic_debug.h>
 15 #include <asm/byteorder.h>
 16 #include <uapi/linux/kernel.h>
 17 
 18 #define USHRT_MAX       ((u16)(~0U))
 19 #define SHRT_MAX        ((s16)(USHRT_MAX>>1))
 20 #define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
 21 #define INT_MAX         ((int)(~0U>>1))
 22 #define INT_MIN         (-INT_MAX - 1)
 23 #define UINT_MAX        (~0U)
 24 #define LONG_MAX        ((long)(~0UL>>1))
 25 #define LONG_MIN        (-LONG_MAX - 1)
 26 #define ULONG_MAX       (~0UL)
 27 #define LLONG_MAX       ((long long)(~0ULL>>1))
 28 #define LLONG_MIN       (-LLONG_MAX - 1)
 29 #define ULLONG_MAX      (~0ULL)
 30 #define SIZE_MAX        (~(size_t)0)
 31 
 32 #define U8_MAX          ((u8)~0U)
 33 #define S8_MAX          ((s8)(U8_MAX>>1))
 34 #define S8_MIN          ((s8)(-S8_MAX - 1))
 35 #define U16_MAX         ((u16)~0U)
 36 #define S16_MAX         ((s16)(U16_MAX>>1))
 37 #define S16_MIN         ((s16)(-S16_MAX - 1))
 38 #define U32_MAX         ((u32)~0U)
 39 #define S32_MAX         ((s32)(U32_MAX>>1))
 40 #define S32_MIN         ((s32)(-S32_MAX - 1))
 41 #define U64_MAX         ((u64)~0ULL)
 42 #define S64_MAX         ((s64)(U64_MAX>>1))
 43 #define S64_MIN         ((s64)(-S64_MAX - 1))
 44 
 45 #define STACK_MAGIC     0xdeadbeef
 46 
 47 #define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
 48 
 49 #define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
 50 #define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
 51 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
 52 #define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
 53 
 54 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 55 
 56 /*
 57  * This looks more complex than it should be. But we need to
 58  * get the type for the ~ right in round_down (it needs to be
 59  * as wide as the result!), and we want to evaluate the macro
 60  * arguments just once each.
 61  */
 62 #define __round_mask(x, y) ((__typeof__(x))((y)-1))
 63 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
 64 #define round_down(x, y) ((x) & ~__round_mask(x, y))
 65 
 66 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
 67 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
 68 #define DIV_ROUND_UP_ULL(ll,d) \
 69         ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
 70 
 71 #if BITS_PER_LONG == 32
 72 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
 73 #else
 74 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
 75 #endif
 76 
 77 /* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
 78 #define roundup(x, y) (                                 \
 79 {                                                       \
 80         const typeof(y) __y = y;                        \
 81         (((x) + (__y - 1)) / __y) * __y;                \
 82 }                                                       \
 83 )
 84 #define rounddown(x, y) (                               \
 85 {                                                       \
 86         typeof(x) __x = (x);                            \
 87         __x - (__x % (y));                              \
 88 }                                                       \
 89 )
 90 
 91 /*
 92  * Divide positive or negative dividend by positive divisor and round
 93  * to closest integer. Result is undefined for negative divisors and
 94  * for negative dividends if the divisor variable type is unsigned.
 95  */
 96 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
 97 {                                                       \
 98         typeof(x) __x = x;                              \
 99         typeof(divisor) __d = divisor;                  \
100         (((typeof(x))-1) > 0 ||                         \
101          ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
102                 (((__x) + ((__d) / 2)) / (__d)) :       \
103                 (((__x) - ((__d) / 2)) / (__d));        \
104 }                                                       \
105 )
106 /*
107  * Same as above but for u64 dividends. divisor must be a 32-bit
108  * number.
109  */
110 #define DIV_ROUND_CLOSEST_ULL(x, divisor)(              \
111 {                                                       \
112         typeof(divisor) __d = divisor;                  \
113         unsigned long long _tmp = (x) + (__d) / 2;      \
114         do_div(_tmp, __d);                              \
115         _tmp;                                           \
116 }                                                       \
117 )
118 
119 /*
120  * Multiplies an integer by a fraction, while avoiding unnecessary
121  * overflow or loss of precision.
122  */
123 #define mult_frac(x, numer, denom)(                     \
124 {                                                       \
125         typeof(x) quot = (x) / (denom);                 \
126         typeof(x) rem  = (x) % (denom);                 \
127         (quot * (numer)) + ((rem * (numer)) / (denom)); \
128 }                                                       \
129 )
130 
131 
132 #define _RET_IP_                (unsigned long)__builtin_return_address(0)
133 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
134 
135 #ifdef CONFIG_LBDAF
136 # include <asm/div64.h>
137 # define sector_div(a, b) do_div(a, b)
138 #else
139 # define sector_div(n, b)( \
140 { \
141         int _res; \
142         _res = (n) % (b); \
143         (n) /= (b); \
144         _res; \
145 } \
146 )
147 #endif
148 
149 /**
150  * upper_32_bits - return bits 32-63 of a number
151  * @n: the number we're accessing
152  *
153  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
154  * the "right shift count >= width of type" warning when that quantity is
155  * 32-bits.
156  */
157 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
158 
159 /**
160  * lower_32_bits - return bits 0-31 of a number
161  * @n: the number we're accessing
162  */
163 #define lower_32_bits(n) ((u32)(n))
164 
165 struct completion;
166 struct pt_regs;
167 struct user;
168 
169 #ifdef CONFIG_PREEMPT_VOLUNTARY
170 extern int _cond_resched(void);
171 # define might_resched() _cond_resched()
172 #else
173 # define might_resched() do { } while (0)
174 #endif
175 
176 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
177   void ___might_sleep(const char *file, int line, int preempt_offset);
178   void __might_sleep(const char *file, int line, int preempt_offset);
179 /**
180  * might_sleep - annotation for functions that can sleep
181  *
182  * this macro will print a stack trace if it is executed in an atomic
183  * context (spinlock, irq-handler, ...).
184  *
185  * This is a useful debugging help to be able to catch problems early and not
186  * be bitten later when the calling function happens to sleep when it is not
187  * supposed to.
188  */
189 # define might_sleep() \
190         do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
191 # define sched_annotate_sleep() (current->task_state_change = 0)
192 #else
193   static inline void ___might_sleep(const char *file, int line,
194                                    int preempt_offset) { }
195   static inline void __might_sleep(const char *file, int line,
196                                    int preempt_offset) { }
197 # define might_sleep() do { might_resched(); } while (0)
198 # define sched_annotate_sleep() do { } while (0)
199 #endif
200 
201 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
202 
203 /*
204  * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
205  * input types abs() returns a signed long.
206  * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
207  * for those.
208  */
209 #define abs(x) ({                                               \
210                 long ret;                                       \
211                 if (sizeof(x) == sizeof(long)) {                \
212                         long __x = (x);                         \
213                         ret = (__x < 0) ? -__x : __x;           \
214                 } else {                                        \
215                         int __x = (x);                          \
216                         ret = (__x < 0) ? -__x : __x;           \
217                 }                                               \
218                 ret;                                            \
219         })
220 
221 #define abs64(x) ({                             \
222                 s64 __x = (x);                  \
223                 (__x < 0) ? -__x : __x;         \
224         })
225 
226 /**
227  * reciprocal_scale - "scale" a value into range [0, ep_ro)
228  * @val: value
229  * @ep_ro: right open interval endpoint
230  *
231  * Perform a "reciprocal multiplication" in order to "scale" a value into
232  * range [0, ep_ro), where the upper interval endpoint is right-open.
233  * This is useful, e.g. for accessing a index of an array containing
234  * ep_ro elements, for example. Think of it as sort of modulus, only that
235  * the result isn't that of modulo. ;) Note that if initial input is a
236  * small value, then result will return 0.
237  *
238  * Return: a result based on val in interval [0, ep_ro).
239  */
240 static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
241 {
242         return (u32)(((u64) val * ep_ro) >> 32);
243 }
244 
245 #if defined(CONFIG_MMU) && \
246         (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
247 #define might_fault() __might_fault(__FILE__, __LINE__)
248 void __might_fault(const char *file, int line);
249 #else
250 static inline void might_fault(void) { }
251 #endif
252 
253 extern struct atomic_notifier_head panic_notifier_list;
254 extern long (*panic_blink)(int state);
255 __printf(1, 2)
256 void panic(const char *fmt, ...)
257         __noreturn __cold;
258 extern void oops_enter(void);
259 extern void oops_exit(void);
260 void print_oops_end_marker(void);
261 extern int oops_may_print(void);
262 void do_exit(long error_code)
263         __noreturn;
264 void complete_and_exit(struct completion *, long)
265         __noreturn;
266 
267 /* Internal, do not use. */
268 int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
269 int __must_check _kstrtol(const char *s, unsigned int base, long *res);
270 
271 int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
272 int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
273 
274 /**
275  * kstrtoul - convert a string to an unsigned long
276  * @s: The start of the string. The string must be null-terminated, and may also
277  *  include a single newline before its terminating null. The first character
278  *  may also be a plus sign, but not a minus sign.
279  * @base: The number base to use. The maximum supported base is 16. If base is
280  *  given as 0, then the base of the string is automatically detected with the
281  *  conventional semantics - If it begins with 0x the number will be parsed as a
282  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
283  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
284  * @res: Where to write the result of the conversion on success.
285  *
286  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
287  * Used as a replacement for the obsolete simple_strtoull. Return code must
288  * be checked.
289 */
290 static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
291 {
292         /*
293          * We want to shortcut function call, but
294          * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
295          */
296         if (sizeof(unsigned long) == sizeof(unsigned long long) &&
297             __alignof__(unsigned long) == __alignof__(unsigned long long))
298                 return kstrtoull(s, base, (unsigned long long *)res);
299         else
300                 return _kstrtoul(s, base, res);
301 }
302 
303 /**
304  * kstrtol - convert a string to a long
305  * @s: The start of the string. The string must be null-terminated, and may also
306  *  include a single newline before its terminating null. The first character
307  *  may also be a plus sign or a minus sign.
308  * @base: The number base to use. The maximum supported base is 16. If base is
309  *  given as 0, then the base of the string is automatically detected with the
310  *  conventional semantics - If it begins with 0x the number will be parsed as a
311  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
312  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
313  * @res: Where to write the result of the conversion on success.
314  *
315  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
316  * Used as a replacement for the obsolete simple_strtoull. Return code must
317  * be checked.
318  */
319 static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
320 {
321         /*
322          * We want to shortcut function call, but
323          * __builtin_types_compatible_p(long, long long) = 0.
324          */
325         if (sizeof(long) == sizeof(long long) &&
326             __alignof__(long) == __alignof__(long long))
327                 return kstrtoll(s, base, (long long *)res);
328         else
329                 return _kstrtol(s, base, res);
330 }
331 
332 int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
333 int __must_check kstrtoint(const char *s, unsigned int base, int *res);
334 
335 static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
336 {
337         return kstrtoull(s, base, res);
338 }
339 
340 static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
341 {
342         return kstrtoll(s, base, res);
343 }
344 
345 static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
346 {
347         return kstrtouint(s, base, res);
348 }
349 
350 static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
351 {
352         return kstrtoint(s, base, res);
353 }
354 
355 int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
356 int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
357 int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
358 int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
359 
360 int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
361 int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
362 int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
363 int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
364 int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
365 int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
366 int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
367 int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
368 int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
369 int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
370 
371 static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
372 {
373         return kstrtoull_from_user(s, count, base, res);
374 }
375 
376 static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
377 {
378         return kstrtoll_from_user(s, count, base, res);
379 }
380 
381 static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
382 {
383         return kstrtouint_from_user(s, count, base, res);
384 }
385 
386 static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
387 {
388         return kstrtoint_from_user(s, count, base, res);
389 }
390 
391 /* Obsolete, do not use.  Use kstrto<foo> instead */
392 
393 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
394 extern long simple_strtol(const char *,char **,unsigned int);
395 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
396 extern long long simple_strtoll(const char *,char **,unsigned int);
397 
398 extern int num_to_str(char *buf, int size, unsigned long long num);
399 
400 /* lib/printf utilities */
401 
402 extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
403 extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
404 extern __printf(3, 4)
405 int snprintf(char *buf, size_t size, const char *fmt, ...);
406 extern __printf(3, 0)
407 int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
408 extern __printf(3, 4)
409 int scnprintf(char *buf, size_t size, const char *fmt, ...);
410 extern __printf(3, 0)
411 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
412 extern __printf(2, 3)
413 char *kasprintf(gfp_t gfp, const char *fmt, ...);
414 extern __printf(2, 0)
415 char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
416 
417 extern __scanf(2, 3)
418 int sscanf(const char *, const char *, ...);
419 extern __scanf(2, 0)
420 int vsscanf(const char *, const char *, va_list);
421 
422 extern int get_option(char **str, int *pint);
423 extern char *get_options(const char *str, int nints, int *ints);
424 extern unsigned long long memparse(const char *ptr, char **retptr);
425 extern bool parse_option_str(const char *str, const char *option);
426 
427 extern int core_kernel_text(unsigned long addr);
428 extern int core_kernel_data(unsigned long addr);
429 extern int __kernel_text_address(unsigned long addr);
430 extern int kernel_text_address(unsigned long addr);
431 extern int func_ptr_is_kernel_text(void *ptr);
432 
433 unsigned long int_sqrt(unsigned long);
434 
435 extern void bust_spinlocks(int yes);
436 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
437 extern int panic_timeout;
438 extern int panic_on_oops;
439 extern int panic_on_unrecovered_nmi;
440 extern int panic_on_io_nmi;
441 extern int panic_on_warn;
442 extern int sysctl_panic_on_stackoverflow;
443 
444 extern bool crash_kexec_post_notifiers;
445 
446 /*
447  * Only to be used by arch init code. If the user over-wrote the default
448  * CONFIG_PANIC_TIMEOUT, honor it.
449  */
450 static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
451 {
452         if (panic_timeout == arch_default_timeout)
453                 panic_timeout = timeout;
454 }
455 extern const char *print_tainted(void);
456 enum lockdep_ok {
457         LOCKDEP_STILL_OK,
458         LOCKDEP_NOW_UNRELIABLE
459 };
460 extern void add_taint(unsigned flag, enum lockdep_ok);
461 extern int test_taint(unsigned flag);
462 extern unsigned long get_taint(void);
463 extern int root_mountflags;
464 
465 extern bool early_boot_irqs_disabled;
466 
467 /* Values used for system_state */
468 extern enum system_states {
469         SYSTEM_BOOTING,
470         SYSTEM_RUNNING,
471         SYSTEM_HALT,
472         SYSTEM_POWER_OFF,
473         SYSTEM_RESTART,
474 } system_state;
475 
476 #define TAINT_PROPRIETARY_MODULE        0
477 #define TAINT_FORCED_MODULE             1
478 #define TAINT_CPU_OUT_OF_SPEC           2
479 #define TAINT_FORCED_RMMOD              3
480 #define TAINT_MACHINE_CHECK             4
481 #define TAINT_BAD_PAGE                  5
482 #define TAINT_USER                      6
483 #define TAINT_DIE                       7
484 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
485 #define TAINT_WARN                      9
486 #define TAINT_CRAP                      10
487 #define TAINT_FIRMWARE_WORKAROUND       11
488 #define TAINT_OOT_MODULE                12
489 #define TAINT_UNSIGNED_MODULE           13
490 #define TAINT_SOFTLOCKUP                14
491 #define TAINT_LIVEPATCH                 15
492 
493 extern const char hex_asc[];
494 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
495 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
496 
497 static inline char *hex_byte_pack(char *buf, u8 byte)
498 {
499         *buf++ = hex_asc_hi(byte);
500         *buf++ = hex_asc_lo(byte);
501         return buf;
502 }
503 
504 extern const char hex_asc_upper[];
505 #define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
506 #define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
507 
508 static inline char *hex_byte_pack_upper(char *buf, u8 byte)
509 {
510         *buf++ = hex_asc_upper_hi(byte);
511         *buf++ = hex_asc_upper_lo(byte);
512         return buf;
513 }
514 
515 extern int hex_to_bin(char ch);
516 extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
517 extern char *bin2hex(char *dst, const void *src, size_t count);
518 
519 bool mac_pton(const char *s, u8 *mac);
520 
521 /*
522  * General tracing related utility functions - trace_printk(),
523  * tracing_on/tracing_off and tracing_start()/tracing_stop
524  *
525  * Use tracing_on/tracing_off when you want to quickly turn on or off
526  * tracing. It simply enables or disables the recording of the trace events.
527  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
528  * file, which gives a means for the kernel and userspace to interact.
529  * Place a tracing_off() in the kernel where you want tracing to end.
530  * From user space, examine the trace, and then echo 1 > tracing_on
531  * to continue tracing.
532  *
533  * tracing_stop/tracing_start has slightly more overhead. It is used
534  * by things like suspend to ram where disabling the recording of the
535  * trace is not enough, but tracing must actually stop because things
536  * like calling smp_processor_id() may crash the system.
537  *
538  * Most likely, you want to use tracing_on/tracing_off.
539  */
540 
541 enum ftrace_dump_mode {
542         DUMP_NONE,
543         DUMP_ALL,
544         DUMP_ORIG,
545 };
546 
547 #ifdef CONFIG_TRACING
548 void tracing_on(void);
549 void tracing_off(void);
550 int tracing_is_on(void);
551 void tracing_snapshot(void);
552 void tracing_snapshot_alloc(void);
553 
554 extern void tracing_start(void);
555 extern void tracing_stop(void);
556 
557 static inline __printf(1, 2)
558 void ____trace_printk_check_format(const char *fmt, ...)
559 {
560 }
561 #define __trace_printk_check_format(fmt, args...)                       \
562 do {                                                                    \
563         if (0)                                                          \
564                 ____trace_printk_check_format(fmt, ##args);             \
565 } while (0)
566 
567 /**
568  * trace_printk - printf formatting in the ftrace buffer
569  * @fmt: the printf format for printing
570  *
571  * Note: __trace_printk is an internal function for trace_printk and
572  *       the @ip is passed in via the trace_printk macro.
573  *
574  * This function allows a kernel developer to debug fast path sections
575  * that printk is not appropriate for. By scattering in various
576  * printk like tracing in the code, a developer can quickly see
577  * where problems are occurring.
578  *
579  * This is intended as a debugging tool for the developer only.
580  * Please refrain from leaving trace_printks scattered around in
581  * your code. (Extra memory is used for special buffers that are
582  * allocated when trace_printk() is used)
583  *
584  * A little optization trick is done here. If there's only one
585  * argument, there's no need to scan the string for printf formats.
586  * The trace_puts() will suffice. But how can we take advantage of
587  * using trace_puts() when trace_printk() has only one argument?
588  * By stringifying the args and checking the size we can tell
589  * whether or not there are args. __stringify((__VA_ARGS__)) will
590  * turn into "()\0" with a size of 3 when there are no args, anything
591  * else will be bigger. All we need to do is define a string to this,
592  * and then take its size and compare to 3. If it's bigger, use
593  * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
594  * let gcc optimize the rest.
595  */
596 
597 #define trace_printk(fmt, ...)                          \
598 do {                                                    \
599         char _______STR[] = __stringify((__VA_ARGS__)); \
600         if (sizeof(_______STR) > 3)                     \
601                 do_trace_printk(fmt, ##__VA_ARGS__);    \
602         else                                            \
603                 trace_puts(fmt);                        \
604 } while (0)
605 
606 #define do_trace_printk(fmt, args...)                                   \
607 do {                                                                    \
608         static const char *trace_printk_fmt                             \
609                 __attribute__((section("__trace_printk_fmt"))) =        \
610                 __builtin_constant_p(fmt) ? fmt : NULL;                 \
611                                                                         \
612         __trace_printk_check_format(fmt, ##args);                       \
613                                                                         \
614         if (__builtin_constant_p(fmt))                                  \
615                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
616         else                                                            \
617                 __trace_printk(_THIS_IP_, fmt, ##args);                 \
618 } while (0)
619 
620 extern __printf(2, 3)
621 int __trace_bprintk(unsigned long ip, const char *fmt, ...);
622 
623 extern __printf(2, 3)
624 int __trace_printk(unsigned long ip, const char *fmt, ...);
625 
626 /**
627  * trace_puts - write a string into the ftrace buffer
628  * @str: the string to record
629  *
630  * Note: __trace_bputs is an internal function for trace_puts and
631  *       the @ip is passed in via the trace_puts macro.
632  *
633  * This is similar to trace_printk() but is made for those really fast
634  * paths that a developer wants the least amount of "Heisenbug" affects,
635  * where the processing of the print format is still too much.
636  *
637  * This function allows a kernel developer to debug fast path sections
638  * that printk is not appropriate for. By scattering in various
639  * printk like tracing in the code, a developer can quickly see
640  * where problems are occurring.
641  *
642  * This is intended as a debugging tool for the developer only.
643  * Please refrain from leaving trace_puts scattered around in
644  * your code. (Extra memory is used for special buffers that are
645  * allocated when trace_puts() is used)
646  *
647  * Returns: 0 if nothing was written, positive # if string was.
648  *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
649  */
650 
651 #define trace_puts(str) ({                                              \
652         static const char *trace_printk_fmt                             \
653                 __attribute__((section("__trace_printk_fmt"))) =        \
654                 __builtin_constant_p(str) ? str : NULL;                 \
655                                                                         \
656         if (__builtin_constant_p(str))                                  \
657                 __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
658         else                                                            \
659                 __trace_puts(_THIS_IP_, str, strlen(str));              \
660 })
661 extern int __trace_bputs(unsigned long ip, const char *str);
662 extern int __trace_puts(unsigned long ip, const char *str, int size);
663 
664 extern void trace_dump_stack(int skip);
665 
666 /*
667  * The double __builtin_constant_p is because gcc will give us an error
668  * if we try to allocate the static variable to fmt if it is not a
669  * constant. Even with the outer if statement.
670  */
671 #define ftrace_vprintk(fmt, vargs)                                      \
672 do {                                                                    \
673         if (__builtin_constant_p(fmt)) {                                \
674                 static const char *trace_printk_fmt                     \
675                   __attribute__((section("__trace_printk_fmt"))) =      \
676                         __builtin_constant_p(fmt) ? fmt : NULL;         \
677                                                                         \
678                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
679         } else                                                          \
680                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
681 } while (0)
682 
683 extern __printf(2, 0) int
684 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
685 
686 extern __printf(2, 0) int
687 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
688 
689 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
690 #else
691 static inline void tracing_start(void) { }
692 static inline void tracing_stop(void) { }
693 static inline void trace_dump_stack(int skip) { }
694 
695 static inline void tracing_on(void) { }
696 static inline void tracing_off(void) { }
697 static inline int tracing_is_on(void) { return 0; }
698 static inline void tracing_snapshot(void) { }
699 static inline void tracing_snapshot_alloc(void) { }
700 
701 static inline __printf(1, 2)
702 int trace_printk(const char *fmt, ...)
703 {
704         return 0;
705 }
706 static __printf(1, 0) inline int
707 ftrace_vprintk(const char *fmt, va_list ap)
708 {
709         return 0;
710 }
711 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
712 #endif /* CONFIG_TRACING */
713 
714 /*
715  * min()/max()/clamp() macros that also do
716  * strict type-checking.. See the
717  * "unnecessary" pointer comparison.
718  */
719 #define min(x, y) ({                            \
720         typeof(x) _min1 = (x);                  \
721         typeof(y) _min2 = (y);                  \
722         (void) (&_min1 == &_min2);              \
723         _min1 < _min2 ? _min1 : _min2; })
724 
725 #define max(x, y) ({                            \
726         typeof(x) _max1 = (x);                  \
727         typeof(y) _max2 = (y);                  \
728         (void) (&_max1 == &_max2);              \
729         _max1 > _max2 ? _max1 : _max2; })
730 
731 #define min3(x, y, z) min((typeof(x))min(x, y), z)
732 #define max3(x, y, z) max((typeof(x))max(x, y), z)
733 
734 /**
735  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
736  * @x: value1
737  * @y: value2
738  */
739 #define min_not_zero(x, y) ({                   \
740         typeof(x) __x = (x);                    \
741         typeof(y) __y = (y);                    \
742         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
743 
744 /**
745  * clamp - return a value clamped to a given range with strict typechecking
746  * @val: current value
747  * @lo: lowest allowable value
748  * @hi: highest allowable value
749  *
750  * This macro does strict typechecking of lo/hi to make sure they are of the
751  * same type as val.  See the unnecessary pointer comparisons.
752  */
753 #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
754 
755 /*
756  * ..and if you can't take the strict
757  * types, you can specify one yourself.
758  *
759  * Or not use min/max/clamp at all, of course.
760  */
761 #define min_t(type, x, y) ({                    \
762         type __min1 = (x);                      \
763         type __min2 = (y);                      \
764         __min1 < __min2 ? __min1: __min2; })
765 
766 #define max_t(type, x, y) ({                    \
767         type __max1 = (x);                      \
768         type __max2 = (y);                      \
769         __max1 > __max2 ? __max1: __max2; })
770 
771 /**
772  * clamp_t - return a value clamped to a given range using a given type
773  * @type: the type of variable to use
774  * @val: current value
775  * @lo: minimum allowable value
776  * @hi: maximum allowable value
777  *
778  * This macro does no typechecking and uses temporary variables of type
779  * 'type' to make all the comparisons.
780  */
781 #define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
782 
783 /**
784  * clamp_val - return a value clamped to a given range using val's type
785  * @val: current value
786  * @lo: minimum allowable value
787  * @hi: maximum allowable value
788  *
789  * This macro does no typechecking and uses temporary variables of whatever
790  * type the input argument 'val' is.  This is useful when val is an unsigned
791  * type and min and max are literals that will otherwise be assigned a signed
792  * integer type.
793  */
794 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
795 
796 
797 /*
798  * swap - swap value of @a and @b
799  */
800 #define swap(a, b) \
801         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
802 
803 /**
804  * container_of - cast a member of a structure out to the containing structure
805  * @ptr:        the pointer to the member.
806  * @type:       the type of the container struct this is embedded in.
807  * @member:     the name of the member within the struct.
808  *
809  */
810 #define container_of(ptr, type, member) ({                      \
811         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
812         (type *)( (char *)__mptr - offsetof(type,member) );})
813 
814 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
815 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
816 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
817 #endif
818 
819 /* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
820 #define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
821         (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
822          BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
823          /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
824          BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
825          BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
826          /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
827          BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
828          /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
829          BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
830          (perms))
831 #endif
832 

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