Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

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 void might_fault(void);
248 #else
249 static inline void might_fault(void) { }
250 #endif
251 
252 extern struct atomic_notifier_head panic_notifier_list;
253 extern long (*panic_blink)(int state);
254 __printf(1, 2)
255 void panic(const char *fmt, ...)
256         __noreturn __cold;
257 extern void oops_enter(void);
258 extern void oops_exit(void);
259 void print_oops_end_marker(void);
260 extern int oops_may_print(void);
261 void do_exit(long error_code)
262         __noreturn;
263 void complete_and_exit(struct completion *, long)
264         __noreturn;
265 
266 /* Internal, do not use. */
267 int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
268 int __must_check _kstrtol(const char *s, unsigned int base, long *res);
269 
270 int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
271 int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
272 
273 /**
274  * kstrtoul - convert a string to an unsigned long
275  * @s: The start of the string. The string must be null-terminated, and may also
276  *  include a single newline before its terminating null. The first character
277  *  may also be a plus sign, but not a minus sign.
278  * @base: The number base to use. The maximum supported base is 16. If base is
279  *  given as 0, then the base of the string is automatically detected with the
280  *  conventional semantics - If it begins with 0x the number will be parsed as a
281  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
282  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
283  * @res: Where to write the result of the conversion on success.
284  *
285  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
286  * Used as a replacement for the obsolete simple_strtoull. Return code must
287  * be checked.
288 */
289 static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
290 {
291         /*
292          * We want to shortcut function call, but
293          * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
294          */
295         if (sizeof(unsigned long) == sizeof(unsigned long long) &&
296             __alignof__(unsigned long) == __alignof__(unsigned long long))
297                 return kstrtoull(s, base, (unsigned long long *)res);
298         else
299                 return _kstrtoul(s, base, res);
300 }
301 
302 /**
303  * kstrtol - convert a string to a long
304  * @s: The start of the string. The string must be null-terminated, and may also
305  *  include a single newline before its terminating null. The first character
306  *  may also be a plus sign or a minus sign.
307  * @base: The number base to use. The maximum supported base is 16. If base is
308  *  given as 0, then the base of the string is automatically detected with the
309  *  conventional semantics - If it begins with 0x the number will be parsed as a
310  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
311  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
312  * @res: Where to write the result of the conversion on success.
313  *
314  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
315  * Used as a replacement for the obsolete simple_strtoull. Return code must
316  * be checked.
317  */
318 static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
319 {
320         /*
321          * We want to shortcut function call, but
322          * __builtin_types_compatible_p(long, long long) = 0.
323          */
324         if (sizeof(long) == sizeof(long long) &&
325             __alignof__(long) == __alignof__(long long))
326                 return kstrtoll(s, base, (long long *)res);
327         else
328                 return _kstrtol(s, base, res);
329 }
330 
331 int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
332 int __must_check kstrtoint(const char *s, unsigned int base, int *res);
333 
334 static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
335 {
336         return kstrtoull(s, base, res);
337 }
338 
339 static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
340 {
341         return kstrtoll(s, base, res);
342 }
343 
344 static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
345 {
346         return kstrtouint(s, base, res);
347 }
348 
349 static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
350 {
351         return kstrtoint(s, base, res);
352 }
353 
354 int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
355 int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
356 int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
357 int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
358 
359 int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
360 int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
361 int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
362 int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
363 int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
364 int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
365 int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
366 int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
367 int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
368 int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
369 
370 static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
371 {
372         return kstrtoull_from_user(s, count, base, res);
373 }
374 
375 static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
376 {
377         return kstrtoll_from_user(s, count, base, res);
378 }
379 
380 static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
381 {
382         return kstrtouint_from_user(s, count, base, res);
383 }
384 
385 static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
386 {
387         return kstrtoint_from_user(s, count, base, res);
388 }
389 
390 /* Obsolete, do not use.  Use kstrto<foo> instead */
391 
392 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
393 extern long simple_strtol(const char *,char **,unsigned int);
394 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
395 extern long long simple_strtoll(const char *,char **,unsigned int);
396 
397 extern int num_to_str(char *buf, int size, unsigned long long num);
398 
399 /* lib/printf utilities */
400 
401 extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
402 extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
403 extern __printf(3, 4)
404 int snprintf(char *buf, size_t size, const char *fmt, ...);
405 extern __printf(3, 0)
406 int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
407 extern __printf(3, 4)
408 int scnprintf(char *buf, size_t size, const char *fmt, ...);
409 extern __printf(3, 0)
410 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
411 extern __printf(2, 3)
412 char *kasprintf(gfp_t gfp, const char *fmt, ...);
413 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
414 
415 extern __scanf(2, 3)
416 int sscanf(const char *, const char *, ...);
417 extern __scanf(2, 0)
418 int vsscanf(const char *, const char *, va_list);
419 
420 extern int get_option(char **str, int *pint);
421 extern char *get_options(const char *str, int nints, int *ints);
422 extern unsigned long long memparse(const char *ptr, char **retptr);
423 extern bool parse_option_str(const char *str, const char *option);
424 
425 extern int core_kernel_text(unsigned long addr);
426 extern int core_kernel_data(unsigned long addr);
427 extern int __kernel_text_address(unsigned long addr);
428 extern int kernel_text_address(unsigned long addr);
429 extern int func_ptr_is_kernel_text(void *ptr);
430 
431 unsigned long int_sqrt(unsigned long);
432 
433 extern void bust_spinlocks(int yes);
434 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
435 extern int panic_timeout;
436 extern int panic_on_oops;
437 extern int panic_on_unrecovered_nmi;
438 extern int panic_on_io_nmi;
439 extern int panic_on_warn;
440 extern int sysctl_panic_on_stackoverflow;
441 /*
442  * Only to be used by arch init code. If the user over-wrote the default
443  * CONFIG_PANIC_TIMEOUT, honor it.
444  */
445 static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
446 {
447         if (panic_timeout == arch_default_timeout)
448                 panic_timeout = timeout;
449 }
450 extern const char *print_tainted(void);
451 enum lockdep_ok {
452         LOCKDEP_STILL_OK,
453         LOCKDEP_NOW_UNRELIABLE
454 };
455 extern void add_taint(unsigned flag, enum lockdep_ok);
456 extern int test_taint(unsigned flag);
457 extern unsigned long get_taint(void);
458 extern int root_mountflags;
459 
460 extern bool early_boot_irqs_disabled;
461 
462 /* Values used for system_state */
463 extern enum system_states {
464         SYSTEM_BOOTING,
465         SYSTEM_RUNNING,
466         SYSTEM_HALT,
467         SYSTEM_POWER_OFF,
468         SYSTEM_RESTART,
469 } system_state;
470 
471 #define TAINT_PROPRIETARY_MODULE        0
472 #define TAINT_FORCED_MODULE             1
473 #define TAINT_CPU_OUT_OF_SPEC           2
474 #define TAINT_FORCED_RMMOD              3
475 #define TAINT_MACHINE_CHECK             4
476 #define TAINT_BAD_PAGE                  5
477 #define TAINT_USER                      6
478 #define TAINT_DIE                       7
479 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
480 #define TAINT_WARN                      9
481 #define TAINT_CRAP                      10
482 #define TAINT_FIRMWARE_WORKAROUND       11
483 #define TAINT_OOT_MODULE                12
484 #define TAINT_UNSIGNED_MODULE           13
485 #define TAINT_SOFTLOCKUP                14
486 #define TAINT_LIVEPATCH                 15
487 
488 extern const char hex_asc[];
489 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
490 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
491 
492 static inline char *hex_byte_pack(char *buf, u8 byte)
493 {
494         *buf++ = hex_asc_hi(byte);
495         *buf++ = hex_asc_lo(byte);
496         return buf;
497 }
498 
499 extern const char hex_asc_upper[];
500 #define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
501 #define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
502 
503 static inline char *hex_byte_pack_upper(char *buf, u8 byte)
504 {
505         *buf++ = hex_asc_upper_hi(byte);
506         *buf++ = hex_asc_upper_lo(byte);
507         return buf;
508 }
509 
510 extern int hex_to_bin(char ch);
511 extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
512 extern char *bin2hex(char *dst, const void *src, size_t count);
513 
514 bool mac_pton(const char *s, u8 *mac);
515 
516 /*
517  * General tracing related utility functions - trace_printk(),
518  * tracing_on/tracing_off and tracing_start()/tracing_stop
519  *
520  * Use tracing_on/tracing_off when you want to quickly turn on or off
521  * tracing. It simply enables or disables the recording of the trace events.
522  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
523  * file, which gives a means for the kernel and userspace to interact.
524  * Place a tracing_off() in the kernel where you want tracing to end.
525  * From user space, examine the trace, and then echo 1 > tracing_on
526  * to continue tracing.
527  *
528  * tracing_stop/tracing_start has slightly more overhead. It is used
529  * by things like suspend to ram where disabling the recording of the
530  * trace is not enough, but tracing must actually stop because things
531  * like calling smp_processor_id() may crash the system.
532  *
533  * Most likely, you want to use tracing_on/tracing_off.
534  */
535 #ifdef CONFIG_RING_BUFFER
536 /* trace_off_permanent stops recording with no way to bring it back */
537 void tracing_off_permanent(void);
538 #else
539 static inline void tracing_off_permanent(void) { }
540 #endif
541 
542 enum ftrace_dump_mode {
543         DUMP_NONE,
544         DUMP_ALL,
545         DUMP_ORIG,
546 };
547 
548 #ifdef CONFIG_TRACING
549 void tracing_on(void);
550 void tracing_off(void);
551 int tracing_is_on(void);
552 void tracing_snapshot(void);
553 void tracing_snapshot_alloc(void);
554 
555 extern void tracing_start(void);
556 extern void tracing_stop(void);
557 
558 static inline __printf(1, 2)
559 void ____trace_printk_check_format(const char *fmt, ...)
560 {
561 }
562 #define __trace_printk_check_format(fmt, args...)                       \
563 do {                                                                    \
564         if (0)                                                          \
565                 ____trace_printk_check_format(fmt, ##args);             \
566 } while (0)
567 
568 /**
569  * trace_printk - printf formatting in the ftrace buffer
570  * @fmt: the printf format for printing
571  *
572  * Note: __trace_printk is an internal function for trace_printk and
573  *       the @ip is passed in via the trace_printk macro.
574  *
575  * This function allows a kernel developer to debug fast path sections
576  * that printk is not appropriate for. By scattering in various
577  * printk like tracing in the code, a developer can quickly see
578  * where problems are occurring.
579  *
580  * This is intended as a debugging tool for the developer only.
581  * Please refrain from leaving trace_printks scattered around in
582  * your code. (Extra memory is used for special buffers that are
583  * allocated when trace_printk() is used)
584  *
585  * A little optization trick is done here. If there's only one
586  * argument, there's no need to scan the string for printf formats.
587  * The trace_puts() will suffice. But how can we take advantage of
588  * using trace_puts() when trace_printk() has only one argument?
589  * By stringifying the args and checking the size we can tell
590  * whether or not there are args. __stringify((__VA_ARGS__)) will
591  * turn into "()\0" with a size of 3 when there are no args, anything
592  * else will be bigger. All we need to do is define a string to this,
593  * and then take its size and compare to 3. If it's bigger, use
594  * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
595  * let gcc optimize the rest.
596  */
597 
598 #define trace_printk(fmt, ...)                          \
599 do {                                                    \
600         char _______STR[] = __stringify((__VA_ARGS__)); \
601         if (sizeof(_______STR) > 3)                     \
602                 do_trace_printk(fmt, ##__VA_ARGS__);    \
603         else                                            \
604                 trace_puts(fmt);                        \
605 } while (0)
606 
607 #define do_trace_printk(fmt, args...)                                   \
608 do {                                                                    \
609         static const char *trace_printk_fmt                             \
610                 __attribute__((section("__trace_printk_fmt"))) =        \
611                 __builtin_constant_p(fmt) ? fmt : NULL;                 \
612                                                                         \
613         __trace_printk_check_format(fmt, ##args);                       \
614                                                                         \
615         if (__builtin_constant_p(fmt))                                  \
616                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
617         else                                                            \
618                 __trace_printk(_THIS_IP_, fmt, ##args);                 \
619 } while (0)
620 
621 extern __printf(2, 3)
622 int __trace_bprintk(unsigned long ip, const char *fmt, ...);
623 
624 extern __printf(2, 3)
625 int __trace_printk(unsigned long ip, const char *fmt, ...);
626 
627 /**
628  * trace_puts - write a string into the ftrace buffer
629  * @str: the string to record
630  *
631  * Note: __trace_bputs is an internal function for trace_puts and
632  *       the @ip is passed in via the trace_puts macro.
633  *
634  * This is similar to trace_printk() but is made for those really fast
635  * paths that a developer wants the least amount of "Heisenbug" affects,
636  * where the processing of the print format is still too much.
637  *
638  * This function allows a kernel developer to debug fast path sections
639  * that printk is not appropriate for. By scattering in various
640  * printk like tracing in the code, a developer can quickly see
641  * where problems are occurring.
642  *
643  * This is intended as a debugging tool for the developer only.
644  * Please refrain from leaving trace_puts scattered around in
645  * your code. (Extra memory is used for special buffers that are
646  * allocated when trace_puts() is used)
647  *
648  * Returns: 0 if nothing was written, positive # if string was.
649  *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
650  */
651 
652 #define trace_puts(str) ({                                              \
653         static const char *trace_printk_fmt                             \
654                 __attribute__((section("__trace_printk_fmt"))) =        \
655                 __builtin_constant_p(str) ? str : NULL;                 \
656                                                                         \
657         if (__builtin_constant_p(str))                                  \
658                 __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
659         else                                                            \
660                 __trace_puts(_THIS_IP_, str, strlen(str));              \
661 })
662 extern int __trace_bputs(unsigned long ip, const char *str);
663 extern int __trace_puts(unsigned long ip, const char *str, int size);
664 
665 extern void trace_dump_stack(int skip);
666 
667 /*
668  * The double __builtin_constant_p is because gcc will give us an error
669  * if we try to allocate the static variable to fmt if it is not a
670  * constant. Even with the outer if statement.
671  */
672 #define ftrace_vprintk(fmt, vargs)                                      \
673 do {                                                                    \
674         if (__builtin_constant_p(fmt)) {                                \
675                 static const char *trace_printk_fmt                     \
676                   __attribute__((section("__trace_printk_fmt"))) =      \
677                         __builtin_constant_p(fmt) ? fmt : NULL;         \
678                                                                         \
679                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
680         } else                                                          \
681                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
682 } while (0)
683 
684 extern int
685 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
686 
687 extern int
688 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
689 
690 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
691 #else
692 static inline void tracing_start(void) { }
693 static inline void tracing_stop(void) { }
694 static inline void trace_dump_stack(int skip) { }
695 
696 static inline void tracing_on(void) { }
697 static inline void tracing_off(void) { }
698 static inline int tracing_is_on(void) { return 0; }
699 static inline void tracing_snapshot(void) { }
700 static inline void tracing_snapshot_alloc(void) { }
701 
702 static inline __printf(1, 2)
703 int trace_printk(const char *fmt, ...)
704 {
705         return 0;
706 }
707 static inline int
708 ftrace_vprintk(const char *fmt, va_list ap)
709 {
710         return 0;
711 }
712 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
713 #endif /* CONFIG_TRACING */
714 
715 /*
716  * min()/max()/clamp() macros that also do
717  * strict type-checking.. See the
718  * "unnecessary" pointer comparison.
719  */
720 #define min(x, y) ({                            \
721         typeof(x) _min1 = (x);                  \
722         typeof(y) _min2 = (y);                  \
723         (void) (&_min1 == &_min2);              \
724         _min1 < _min2 ? _min1 : _min2; })
725 
726 #define max(x, y) ({                            \
727         typeof(x) _max1 = (x);                  \
728         typeof(y) _max2 = (y);                  \
729         (void) (&_max1 == &_max2);              \
730         _max1 > _max2 ? _max1 : _max2; })
731 
732 #define min3(x, y, z) min((typeof(x))min(x, y), z)
733 #define max3(x, y, z) max((typeof(x))max(x, y), z)
734 
735 /**
736  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
737  * @x: value1
738  * @y: value2
739  */
740 #define min_not_zero(x, y) ({                   \
741         typeof(x) __x = (x);                    \
742         typeof(y) __y = (y);                    \
743         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
744 
745 /**
746  * clamp - return a value clamped to a given range with strict typechecking
747  * @val: current value
748  * @lo: lowest allowable value
749  * @hi: highest allowable value
750  *
751  * This macro does strict typechecking of lo/hi to make sure they are of the
752  * same type as val.  See the unnecessary pointer comparisons.
753  */
754 #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
755 
756 /*
757  * ..and if you can't take the strict
758  * types, you can specify one yourself.
759  *
760  * Or not use min/max/clamp at all, of course.
761  */
762 #define min_t(type, x, y) ({                    \
763         type __min1 = (x);                      \
764         type __min2 = (y);                      \
765         __min1 < __min2 ? __min1: __min2; })
766 
767 #define max_t(type, x, y) ({                    \
768         type __max1 = (x);                      \
769         type __max2 = (y);                      \
770         __max1 > __max2 ? __max1: __max2; })
771 
772 /**
773  * clamp_t - return a value clamped to a given range using a given type
774  * @type: the type of variable to use
775  * @val: current value
776  * @lo: minimum allowable value
777  * @hi: maximum allowable value
778  *
779  * This macro does no typechecking and uses temporary variables of type
780  * 'type' to make all the comparisons.
781  */
782 #define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
783 
784 /**
785  * clamp_val - return a value clamped to a given range using val's type
786  * @val: current value
787  * @lo: minimum allowable value
788  * @hi: maximum allowable value
789  *
790  * This macro does no typechecking and uses temporary variables of whatever
791  * type the input argument 'val' is.  This is useful when val is an unsigned
792  * type and min and max are literals that will otherwise be assigned a signed
793  * integer type.
794  */
795 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
796 
797 
798 /*
799  * swap - swap value of @a and @b
800  */
801 #define swap(a, b) \
802         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
803 
804 /**
805  * container_of - cast a member of a structure out to the containing structure
806  * @ptr:        the pointer to the member.
807  * @type:       the type of the container struct this is embedded in.
808  * @member:     the name of the member within the struct.
809  *
810  */
811 #define container_of(ptr, type, member) ({                      \
812         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
813         (type *)( (char *)__mptr - offsetof(type,member) );})
814 
815 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
816 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
817 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
818 #endif
819 
820 /* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
821 #define VERIFY_OCTAL_PERMISSIONS(perms)                                 \
822         (BUILD_BUG_ON_ZERO((perms) < 0) +                               \
823          BUILD_BUG_ON_ZERO((perms) > 0777) +                            \
824          /* User perms >= group perms >= other perms */                 \
825          BUILD_BUG_ON_ZERO(((perms) >> 6) < (((perms) >> 3) & 7)) +     \
826          BUILD_BUG_ON_ZERO((((perms) >> 3) & 7) < ((perms) & 7)) +      \
827          /* Other writable?  Generally considered a bad idea. */        \
828          BUILD_BUG_ON_ZERO((perms) & 2) +                               \
829          (perms))
830 #endif
831 

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