Version:  2.0.40 2.2.26 2.4.37 3.11 3.12 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

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 <asm/byteorder.h>
 15 #include <uapi/linux/kernel.h>
 16 
 17 #define USHRT_MAX       ((u16)(~0U))
 18 #define SHRT_MAX        ((s16)(USHRT_MAX>>1))
 19 #define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
 20 #define INT_MAX         ((int)(~0U>>1))
 21 #define INT_MIN         (-INT_MAX - 1)
 22 #define UINT_MAX        (~0U)
 23 #define LONG_MAX        ((long)(~0UL>>1))
 24 #define LONG_MIN        (-LONG_MAX - 1)
 25 #define ULONG_MAX       (~0UL)
 26 #define LLONG_MAX       ((long long)(~0ULL>>1))
 27 #define LLONG_MIN       (-LLONG_MAX - 1)
 28 #define ULLONG_MAX      (~0ULL)
 29 #define SIZE_MAX        (~(size_t)0)
 30 
 31 #define U8_MAX          ((u8)~0U)
 32 #define S8_MAX          ((s8)(U8_MAX>>1))
 33 #define S8_MIN          ((s8)(-S8_MAX - 1))
 34 #define U16_MAX         ((u16)~0U)
 35 #define S16_MAX         ((s16)(U16_MAX>>1))
 36 #define S16_MIN         ((s16)(-S16_MAX - 1))
 37 #define U32_MAX         ((u32)~0U)
 38 #define S32_MAX         ((s32)(U32_MAX>>1))
 39 #define S32_MIN         ((s32)(-S32_MAX - 1))
 40 #define U64_MAX         ((u64)~0ULL)
 41 #define S64_MAX         ((s64)(U64_MAX>>1))
 42 #define S64_MIN         ((s64)(-S64_MAX - 1))
 43 
 44 #define STACK_MAGIC     0xdeadbeef
 45 
 46 #define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
 47 
 48 #define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
 49 #define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
 50 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
 51 #define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
 52 
 53 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 54 
 55 #define u64_to_user_ptr(x) (            \
 56 {                                       \
 57         typecheck(u64, x);              \
 58         (void __user *)(uintptr_t)x;    \
 59 }                                       \
 60 )
 61 
 62 /*
 63  * This looks more complex than it should be. But we need to
 64  * get the type for the ~ right in round_down (it needs to be
 65  * as wide as the result!), and we want to evaluate the macro
 66  * arguments just once each.
 67  */
 68 #define __round_mask(x, y) ((__typeof__(x))((y)-1))
 69 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
 70 #define round_down(x, y) ((x) & ~__round_mask(x, y))
 71 
 72 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
 73 #define DIV_ROUND_UP __KERNEL_DIV_ROUND_UP
 74 #define DIV_ROUND_UP_ULL(ll,d) \
 75         ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
 76 
 77 #if BITS_PER_LONG == 32
 78 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
 79 #else
 80 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
 81 #endif
 82 
 83 /* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
 84 #define roundup(x, y) (                                 \
 85 {                                                       \
 86         const typeof(y) __y = y;                        \
 87         (((x) + (__y - 1)) / __y) * __y;                \
 88 }                                                       \
 89 )
 90 #define rounddown(x, y) (                               \
 91 {                                                       \
 92         typeof(x) __x = (x);                            \
 93         __x - (__x % (y));                              \
 94 }                                                       \
 95 )
 96 
 97 /*
 98  * Divide positive or negative dividend by positive divisor and round
 99  * to closest integer. Result is undefined for negative divisors and
100  * for negative dividends if the divisor variable type is unsigned.
101  */
102 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
103 {                                                       \
104         typeof(x) __x = x;                              \
105         typeof(divisor) __d = divisor;                  \
106         (((typeof(x))-1) > 0 ||                         \
107          ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
108                 (((__x) + ((__d) / 2)) / (__d)) :       \
109                 (((__x) - ((__d) / 2)) / (__d));        \
110 }                                                       \
111 )
112 /*
113  * Same as above but for u64 dividends. divisor must be a 32-bit
114  * number.
115  */
116 #define DIV_ROUND_CLOSEST_ULL(x, divisor)(              \
117 {                                                       \
118         typeof(divisor) __d = divisor;                  \
119         unsigned long long _tmp = (x) + (__d) / 2;      \
120         do_div(_tmp, __d);                              \
121         _tmp;                                           \
122 }                                                       \
123 )
124 
125 /*
126  * Multiplies an integer by a fraction, while avoiding unnecessary
127  * overflow or loss of precision.
128  */
129 #define mult_frac(x, numer, denom)(                     \
130 {                                                       \
131         typeof(x) quot = (x) / (denom);                 \
132         typeof(x) rem  = (x) % (denom);                 \
133         (quot * (numer)) + ((rem * (numer)) / (denom)); \
134 }                                                       \
135 )
136 
137 
138 #define _RET_IP_                (unsigned long)__builtin_return_address(0)
139 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
140 
141 #ifdef CONFIG_LBDAF
142 # include <asm/div64.h>
143 # define sector_div(a, b) do_div(a, b)
144 #else
145 # define sector_div(n, b)( \
146 { \
147         int _res; \
148         _res = (n) % (b); \
149         (n) /= (b); \
150         _res; \
151 } \
152 )
153 #endif
154 
155 /**
156  * upper_32_bits - return bits 32-63 of a number
157  * @n: the number we're accessing
158  *
159  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
160  * the "right shift count >= width of type" warning when that quantity is
161  * 32-bits.
162  */
163 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
164 
165 /**
166  * lower_32_bits - return bits 0-31 of a number
167  * @n: the number we're accessing
168  */
169 #define lower_32_bits(n) ((u32)(n))
170 
171 struct completion;
172 struct pt_regs;
173 struct user;
174 
175 #ifdef CONFIG_PREEMPT_VOLUNTARY
176 extern int _cond_resched(void);
177 # define might_resched() _cond_resched()
178 #else
179 # define might_resched() do { } while (0)
180 #endif
181 
182 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
183   void ___might_sleep(const char *file, int line, int preempt_offset);
184   void __might_sleep(const char *file, int line, int preempt_offset);
185 /**
186  * might_sleep - annotation for functions that can sleep
187  *
188  * this macro will print a stack trace if it is executed in an atomic
189  * context (spinlock, irq-handler, ...).
190  *
191  * This is a useful debugging help to be able to catch problems early and not
192  * be bitten later when the calling function happens to sleep when it is not
193  * supposed to.
194  */
195 # define might_sleep() \
196         do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
197 # define sched_annotate_sleep() (current->task_state_change = 0)
198 #else
199   static inline void ___might_sleep(const char *file, int line,
200                                    int preempt_offset) { }
201   static inline void __might_sleep(const char *file, int line,
202                                    int preempt_offset) { }
203 # define might_sleep() do { might_resched(); } while (0)
204 # define sched_annotate_sleep() do { } while (0)
205 #endif
206 
207 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
208 
209 /**
210  * abs - return absolute value of an argument
211  * @x: the value.  If it is unsigned type, it is converted to signed type first.
212  *     char is treated as if it was signed (regardless of whether it really is)
213  *     but the macro's return type is preserved as char.
214  *
215  * Return: an absolute value of x.
216  */
217 #define abs(x)  __abs_choose_expr(x, long long,                         \
218                 __abs_choose_expr(x, long,                              \
219                 __abs_choose_expr(x, int,                               \
220                 __abs_choose_expr(x, short,                             \
221                 __abs_choose_expr(x, char,                              \
222                 __builtin_choose_expr(                                  \
223                         __builtin_types_compatible_p(typeof(x), char),  \
224                         (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
225                         ((void)0)))))))
226 
227 #define __abs_choose_expr(x, type, other) __builtin_choose_expr(        \
228         __builtin_types_compatible_p(typeof(x),   signed type) ||       \
229         __builtin_types_compatible_p(typeof(x), unsigned type),         \
230         ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
231 
232 /**
233  * reciprocal_scale - "scale" a value into range [0, ep_ro)
234  * @val: value
235  * @ep_ro: right open interval endpoint
236  *
237  * Perform a "reciprocal multiplication" in order to "scale" a value into
238  * range [0, ep_ro), where the upper interval endpoint is right-open.
239  * This is useful, e.g. for accessing a index of an array containing
240  * ep_ro elements, for example. Think of it as sort of modulus, only that
241  * the result isn't that of modulo. ;) Note that if initial input is a
242  * small value, then result will return 0.
243  *
244  * Return: a result based on val in interval [0, ep_ro).
245  */
246 static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
247 {
248         return (u32)(((u64) val * ep_ro) >> 32);
249 }
250 
251 #if defined(CONFIG_MMU) && \
252         (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
253 #define might_fault() __might_fault(__FILE__, __LINE__)
254 void __might_fault(const char *file, int line);
255 #else
256 static inline void might_fault(void) { }
257 #endif
258 
259 extern struct atomic_notifier_head panic_notifier_list;
260 extern long (*panic_blink)(int state);
261 __printf(1, 2)
262 void panic(const char *fmt, ...)
263         __noreturn __cold;
264 void nmi_panic(struct pt_regs *regs, const char *msg);
265 extern void oops_enter(void);
266 extern void oops_exit(void);
267 void print_oops_end_marker(void);
268 extern int oops_may_print(void);
269 void do_exit(long error_code)
270         __noreturn;
271 void complete_and_exit(struct completion *, long)
272         __noreturn;
273 
274 /* Internal, do not use. */
275 int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
276 int __must_check _kstrtol(const char *s, unsigned int base, long *res);
277 
278 int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
279 int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
280 
281 /**
282  * kstrtoul - convert a string to an unsigned long
283  * @s: The start of the string. The string must be null-terminated, and may also
284  *  include a single newline before its terminating null. The first character
285  *  may also be a plus sign, but not a minus sign.
286  * @base: The number base to use. The maximum supported base is 16. If base is
287  *  given as 0, then the base of the string is automatically detected with the
288  *  conventional semantics - If it begins with 0x the number will be parsed as a
289  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
290  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
291  * @res: Where to write the result of the conversion on success.
292  *
293  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
294  * Used as a replacement for the obsolete simple_strtoull. Return code must
295  * be checked.
296 */
297 static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
298 {
299         /*
300          * We want to shortcut function call, but
301          * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
302          */
303         if (sizeof(unsigned long) == sizeof(unsigned long long) &&
304             __alignof__(unsigned long) == __alignof__(unsigned long long))
305                 return kstrtoull(s, base, (unsigned long long *)res);
306         else
307                 return _kstrtoul(s, base, res);
308 }
309 
310 /**
311  * kstrtol - convert a string to a long
312  * @s: The start of the string. The string must be null-terminated, and may also
313  *  include a single newline before its terminating null. The first character
314  *  may also be a plus sign or a minus sign.
315  * @base: The number base to use. The maximum supported base is 16. If base is
316  *  given as 0, then the base of the string is automatically detected with the
317  *  conventional semantics - If it begins with 0x the number will be parsed as a
318  *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
319  *  parsed as an octal number. Otherwise it will be parsed as a decimal.
320  * @res: Where to write the result of the conversion on success.
321  *
322  * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
323  * Used as a replacement for the obsolete simple_strtoull. Return code must
324  * be checked.
325  */
326 static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
327 {
328         /*
329          * We want to shortcut function call, but
330          * __builtin_types_compatible_p(long, long long) = 0.
331          */
332         if (sizeof(long) == sizeof(long long) &&
333             __alignof__(long) == __alignof__(long long))
334                 return kstrtoll(s, base, (long long *)res);
335         else
336                 return _kstrtol(s, base, res);
337 }
338 
339 int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
340 int __must_check kstrtoint(const char *s, unsigned int base, int *res);
341 
342 static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
343 {
344         return kstrtoull(s, base, res);
345 }
346 
347 static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
348 {
349         return kstrtoll(s, base, res);
350 }
351 
352 static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
353 {
354         return kstrtouint(s, base, res);
355 }
356 
357 static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
358 {
359         return kstrtoint(s, base, res);
360 }
361 
362 int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
363 int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
364 int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
365 int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
366 int __must_check kstrtobool(const char *s, bool *res);
367 
368 int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
369 int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
370 int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
371 int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
372 int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
373 int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
374 int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
375 int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
376 int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
377 int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
378 int __must_check kstrtobool_from_user(const char __user *s, size_t count, bool *res);
379 
380 static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
381 {
382         return kstrtoull_from_user(s, count, base, res);
383 }
384 
385 static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
386 {
387         return kstrtoll_from_user(s, count, base, res);
388 }
389 
390 static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
391 {
392         return kstrtouint_from_user(s, count, base, res);
393 }
394 
395 static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
396 {
397         return kstrtoint_from_user(s, count, base, res);
398 }
399 
400 /* Obsolete, do not use.  Use kstrto<foo> instead */
401 
402 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
403 extern long simple_strtol(const char *,char **,unsigned int);
404 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
405 extern long long simple_strtoll(const char *,char **,unsigned int);
406 
407 extern int num_to_str(char *buf, int size, unsigned long long num);
408 
409 /* lib/printf utilities */
410 
411 extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
412 extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
413 extern __printf(3, 4)
414 int snprintf(char *buf, size_t size, const char *fmt, ...);
415 extern __printf(3, 0)
416 int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
417 extern __printf(3, 4)
418 int scnprintf(char *buf, size_t size, const char *fmt, ...);
419 extern __printf(3, 0)
420 int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
421 extern __printf(2, 3) __malloc
422 char *kasprintf(gfp_t gfp, const char *fmt, ...);
423 extern __printf(2, 0) __malloc
424 char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
425 extern __printf(2, 0)
426 const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);
427 
428 extern __scanf(2, 3)
429 int sscanf(const char *, const char *, ...);
430 extern __scanf(2, 0)
431 int vsscanf(const char *, const char *, va_list);
432 
433 extern int get_option(char **str, int *pint);
434 extern char *get_options(const char *str, int nints, int *ints);
435 extern unsigned long long memparse(const char *ptr, char **retptr);
436 extern bool parse_option_str(const char *str, const char *option);
437 
438 extern int core_kernel_text(unsigned long addr);
439 extern int core_kernel_data(unsigned long addr);
440 extern int __kernel_text_address(unsigned long addr);
441 extern int kernel_text_address(unsigned long addr);
442 extern int func_ptr_is_kernel_text(void *ptr);
443 
444 unsigned long int_sqrt(unsigned long);
445 
446 extern void bust_spinlocks(int yes);
447 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
448 extern int panic_timeout;
449 extern int panic_on_oops;
450 extern int panic_on_unrecovered_nmi;
451 extern int panic_on_io_nmi;
452 extern int panic_on_warn;
453 extern int sysctl_panic_on_rcu_stall;
454 extern int sysctl_panic_on_stackoverflow;
455 
456 extern bool crash_kexec_post_notifiers;
457 
458 /*
459  * panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
460  * holds a CPU number which is executing panic() currently. A value of
461  * PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
462  */
463 extern atomic_t panic_cpu;
464 #define PANIC_CPU_INVALID       -1
465 
466 /*
467  * Only to be used by arch init code. If the user over-wrote the default
468  * CONFIG_PANIC_TIMEOUT, honor it.
469  */
470 static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
471 {
472         if (panic_timeout == arch_default_timeout)
473                 panic_timeout = timeout;
474 }
475 extern const char *print_tainted(void);
476 enum lockdep_ok {
477         LOCKDEP_STILL_OK,
478         LOCKDEP_NOW_UNRELIABLE
479 };
480 extern void add_taint(unsigned flag, enum lockdep_ok);
481 extern int test_taint(unsigned flag);
482 extern unsigned long get_taint(void);
483 extern int root_mountflags;
484 
485 extern bool early_boot_irqs_disabled;
486 
487 /* Values used for system_state */
488 extern enum system_states {
489         SYSTEM_BOOTING,
490         SYSTEM_RUNNING,
491         SYSTEM_HALT,
492         SYSTEM_POWER_OFF,
493         SYSTEM_RESTART,
494 } system_state;
495 
496 #define TAINT_PROPRIETARY_MODULE        0
497 #define TAINT_FORCED_MODULE             1
498 #define TAINT_CPU_OUT_OF_SPEC           2
499 #define TAINT_FORCED_RMMOD              3
500 #define TAINT_MACHINE_CHECK             4
501 #define TAINT_BAD_PAGE                  5
502 #define TAINT_USER                      6
503 #define TAINT_DIE                       7
504 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
505 #define TAINT_WARN                      9
506 #define TAINT_CRAP                      10
507 #define TAINT_FIRMWARE_WORKAROUND       11
508 #define TAINT_OOT_MODULE                12
509 #define TAINT_UNSIGNED_MODULE           13
510 #define TAINT_SOFTLOCKUP                14
511 #define TAINT_LIVEPATCH                 15
512 
513 extern const char hex_asc[];
514 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
515 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
516 
517 static inline char *hex_byte_pack(char *buf, u8 byte)
518 {
519         *buf++ = hex_asc_hi(byte);
520         *buf++ = hex_asc_lo(byte);
521         return buf;
522 }
523 
524 extern const char hex_asc_upper[];
525 #define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
526 #define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]
527 
528 static inline char *hex_byte_pack_upper(char *buf, u8 byte)
529 {
530         *buf++ = hex_asc_upper_hi(byte);
531         *buf++ = hex_asc_upper_lo(byte);
532         return buf;
533 }
534 
535 extern int hex_to_bin(char ch);
536 extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
537 extern char *bin2hex(char *dst, const void *src, size_t count);
538 
539 bool mac_pton(const char *s, u8 *mac);
540 
541 /*
542  * General tracing related utility functions - trace_printk(),
543  * tracing_on/tracing_off and tracing_start()/tracing_stop
544  *
545  * Use tracing_on/tracing_off when you want to quickly turn on or off
546  * tracing. It simply enables or disables the recording of the trace events.
547  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
548  * file, which gives a means for the kernel and userspace to interact.
549  * Place a tracing_off() in the kernel where you want tracing to end.
550  * From user space, examine the trace, and then echo 1 > tracing_on
551  * to continue tracing.
552  *
553  * tracing_stop/tracing_start has slightly more overhead. It is used
554  * by things like suspend to ram where disabling the recording of the
555  * trace is not enough, but tracing must actually stop because things
556  * like calling smp_processor_id() may crash the system.
557  *
558  * Most likely, you want to use tracing_on/tracing_off.
559  */
560 
561 enum ftrace_dump_mode {
562         DUMP_NONE,
563         DUMP_ALL,
564         DUMP_ORIG,
565 };
566 
567 #ifdef CONFIG_TRACING
568 void tracing_on(void);
569 void tracing_off(void);
570 int tracing_is_on(void);
571 void tracing_snapshot(void);
572 void tracing_snapshot_alloc(void);
573 
574 extern void tracing_start(void);
575 extern void tracing_stop(void);
576 
577 static inline __printf(1, 2)
578 void ____trace_printk_check_format(const char *fmt, ...)
579 {
580 }
581 #define __trace_printk_check_format(fmt, args...)                       \
582 do {                                                                    \
583         if (0)                                                          \
584                 ____trace_printk_check_format(fmt, ##args);             \
585 } while (0)
586 
587 /**
588  * trace_printk - printf formatting in the ftrace buffer
589  * @fmt: the printf format for printing
590  *
591  * Note: __trace_printk is an internal function for trace_printk and
592  *       the @ip is passed in via the trace_printk macro.
593  *
594  * This function allows a kernel developer to debug fast path sections
595  * that printk is not appropriate for. By scattering in various
596  * printk like tracing in the code, a developer can quickly see
597  * where problems are occurring.
598  *
599  * This is intended as a debugging tool for the developer only.
600  * Please refrain from leaving trace_printks scattered around in
601  * your code. (Extra memory is used for special buffers that are
602  * allocated when trace_printk() is used)
603  *
604  * A little optization trick is done here. If there's only one
605  * argument, there's no need to scan the string for printf formats.
606  * The trace_puts() will suffice. But how can we take advantage of
607  * using trace_puts() when trace_printk() has only one argument?
608  * By stringifying the args and checking the size we can tell
609  * whether or not there are args. __stringify((__VA_ARGS__)) will
610  * turn into "()\0" with a size of 3 when there are no args, anything
611  * else will be bigger. All we need to do is define a string to this,
612  * and then take its size and compare to 3. If it's bigger, use
613  * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
614  * let gcc optimize the rest.
615  */
616 
617 #define trace_printk(fmt, ...)                          \
618 do {                                                    \
619         char _______STR[] = __stringify((__VA_ARGS__)); \
620         if (sizeof(_______STR) > 3)                     \
621                 do_trace_printk(fmt, ##__VA_ARGS__);    \
622         else                                            \
623                 trace_puts(fmt);                        \
624 } while (0)
625 
626 #define do_trace_printk(fmt, args...)                                   \
627 do {                                                                    \
628         static const char *trace_printk_fmt __used                      \
629                 __attribute__((section("__trace_printk_fmt"))) =        \
630                 __builtin_constant_p(fmt) ? fmt : NULL;                 \
631                                                                         \
632         __trace_printk_check_format(fmt, ##args);                       \
633                                                                         \
634         if (__builtin_constant_p(fmt))                                  \
635                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
636         else                                                            \
637                 __trace_printk(_THIS_IP_, fmt, ##args);                 \
638 } while (0)
639 
640 extern __printf(2, 3)
641 int __trace_bprintk(unsigned long ip, const char *fmt, ...);
642 
643 extern __printf(2, 3)
644 int __trace_printk(unsigned long ip, const char *fmt, ...);
645 
646 /**
647  * trace_puts - write a string into the ftrace buffer
648  * @str: the string to record
649  *
650  * Note: __trace_bputs is an internal function for trace_puts and
651  *       the @ip is passed in via the trace_puts macro.
652  *
653  * This is similar to trace_printk() but is made for those really fast
654  * paths that a developer wants the least amount of "Heisenbug" affects,
655  * where the processing of the print format is still too much.
656  *
657  * This function allows a kernel developer to debug fast path sections
658  * that printk is not appropriate for. By scattering in various
659  * printk like tracing in the code, a developer can quickly see
660  * where problems are occurring.
661  *
662  * This is intended as a debugging tool for the developer only.
663  * Please refrain from leaving trace_puts scattered around in
664  * your code. (Extra memory is used for special buffers that are
665  * allocated when trace_puts() is used)
666  *
667  * Returns: 0 if nothing was written, positive # if string was.
668  *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
669  */
670 
671 #define trace_puts(str) ({                                              \
672         static const char *trace_printk_fmt __used                      \
673                 __attribute__((section("__trace_printk_fmt"))) =        \
674                 __builtin_constant_p(str) ? str : NULL;                 \
675                                                                         \
676         if (__builtin_constant_p(str))                                  \
677                 __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
678         else                                                            \
679                 __trace_puts(_THIS_IP_, str, strlen(str));              \
680 })
681 extern int __trace_bputs(unsigned long ip, const char *str);
682 extern int __trace_puts(unsigned long ip, const char *str, int size);
683 
684 extern void trace_dump_stack(int skip);
685 
686 /*
687  * The double __builtin_constant_p is because gcc will give us an error
688  * if we try to allocate the static variable to fmt if it is not a
689  * constant. Even with the outer if statement.
690  */
691 #define ftrace_vprintk(fmt, vargs)                                      \
692 do {                                                                    \
693         if (__builtin_constant_p(fmt)) {                                \
694                 static const char *trace_printk_fmt __used              \
695                   __attribute__((section("__trace_printk_fmt"))) =      \
696                         __builtin_constant_p(fmt) ? fmt : NULL;         \
697                                                                         \
698                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
699         } else                                                          \
700                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
701 } while (0)
702 
703 extern __printf(2, 0) int
704 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
705 
706 extern __printf(2, 0) int
707 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
708 
709 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
710 #else
711 static inline void tracing_start(void) { }
712 static inline void tracing_stop(void) { }
713 static inline void trace_dump_stack(int skip) { }
714 
715 static inline void tracing_on(void) { }
716 static inline void tracing_off(void) { }
717 static inline int tracing_is_on(void) { return 0; }
718 static inline void tracing_snapshot(void) { }
719 static inline void tracing_snapshot_alloc(void) { }
720 
721 static inline __printf(1, 2)
722 int trace_printk(const char *fmt, ...)
723 {
724         return 0;
725 }
726 static __printf(1, 0) inline int
727 ftrace_vprintk(const char *fmt, va_list ap)
728 {
729         return 0;
730 }
731 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
732 #endif /* CONFIG_TRACING */
733 
734 /*
735  * min()/max()/clamp() macros that also do
736  * strict type-checking.. See the
737  * "unnecessary" pointer comparison.
738  */
739 #define min(x, y) ({                            \
740         typeof(x) _min1 = (x);                  \
741         typeof(y) _min2 = (y);                  \
742         (void) (&_min1 == &_min2);              \
743         _min1 < _min2 ? _min1 : _min2; })
744 
745 #define max(x, y) ({                            \
746         typeof(x) _max1 = (x);                  \
747         typeof(y) _max2 = (y);                  \
748         (void) (&_max1 == &_max2);              \
749         _max1 > _max2 ? _max1 : _max2; })
750 
751 #define min3(x, y, z) min((typeof(x))min(x, y), z)
752 #define max3(x, y, z) max((typeof(x))max(x, y), z)
753 
754 /**
755  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
756  * @x: value1
757  * @y: value2
758  */
759 #define min_not_zero(x, y) ({                   \
760         typeof(x) __x = (x);                    \
761         typeof(y) __y = (y);                    \
762         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
763 
764 /**
765  * clamp - return a value clamped to a given range with strict typechecking
766  * @val: current value
767  * @lo: lowest allowable value
768  * @hi: highest allowable value
769  *
770  * This macro does strict typechecking of lo/hi to make sure they are of the
771  * same type as val.  See the unnecessary pointer comparisons.
772  */
773 #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
774 
775 /*
776  * ..and if you can't take the strict
777  * types, you can specify one yourself.
778  *
779  * Or not use min/max/clamp at all, of course.
780  */
781 #define min_t(type, x, y) ({                    \
782         type __min1 = (x);                      \
783         type __min2 = (y);                      \
784         __min1 < __min2 ? __min1: __min2; })
785 
786 #define max_t(type, x, y) ({                    \
787         type __max1 = (x);                      \
788         type __max2 = (y);                      \
789         __max1 > __max2 ? __max1: __max2; })
790 
791 /**
792  * clamp_t - return a value clamped to a given range using a given type
793  * @type: the type of variable to use
794  * @val: current value
795  * @lo: minimum allowable value
796  * @hi: maximum allowable value
797  *
798  * This macro does no typechecking and uses temporary variables of type
799  * 'type' to make all the comparisons.
800  */
801 #define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
802 
803 /**
804  * clamp_val - return a value clamped to a given range using val's type
805  * @val: current value
806  * @lo: minimum allowable value
807  * @hi: maximum allowable value
808  *
809  * This macro does no typechecking and uses temporary variables of whatever
810  * type the input argument 'val' is.  This is useful when val is an unsigned
811  * type and min and max are literals that will otherwise be assigned a signed
812  * integer type.
813  */
814 #define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)
815 
816 
817 /*
818  * swap - swap value of @a and @b
819  */
820 #define swap(a, b) \
821         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
822 
823 /**
824  * container_of - cast a member of a structure out to the containing structure
825  * @ptr:        the pointer to the member.
826  * @type:       the type of the container struct this is embedded in.
827  * @member:     the name of the member within the struct.
828  *
829  */
830 #define container_of(ptr, type, member) ({                      \
831         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
832         (type *)( (char *)__mptr - offsetof(type,member) );})
833 
834 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
835 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
836 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
837 #endif
838 
839 /* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
840 #define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
841         (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
842          BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
843          /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
844          BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
845          BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
846          /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
847          BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
848          /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
849          BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
850          (perms))
851 #endif
852 

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