Version:  2.0.40 2.2.26 2.4.37 3.4 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

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

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