include/linux/kernel.h

   1 #ifndef _LINUX_KERNEL_H
   2 #define _LINUX_KERNEL_H
   3
   4 /*
   5  * 'kernel.h' contains some often-used function prototypes etc
   6  */
   7 #define __ALIGN_KERNEL(x, a)            __ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1)
   8 #define __ALIGN_KERNEL_MASK(x, mask)    (((x) + (mask)) & ~(mask))
   9
  10 #ifdef __KERNEL__
  11
  12 #include <stdarg.h>
  13 #include <linux/linkage.h>
  14 #include <linux/stddef.h>
  15 #include <linux/types.h>
  16 #include <linux/compiler.h>
  17 #include <linux/bitops.h>
  18 #include <linux/log2.h>
  19 #include <linux/typecheck.h>
  20 #include <linux/printk.h>
  21 #include <linux/dynamic_debug.h>
  22 #include <asm/byteorder.h>
  23 #include <asm/bug.h>
  24
  25 #define USHRT_MAX       ((u16)(~0U))
  26 #define SHRT_MAX        ((s16)(USHRT_MAX>>1))
  27 #define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
  28 #define INT_MAX         ((int)(~0U>>1))
  29 #define INT_MIN         (-INT_MAX - 1)
  30 #define UINT_MAX        (~0U)
  31 #define LONG_MAX        ((long)(~0UL>>1))
  32 #define LONG_MIN        (-LONG_MAX - 1)
  33 #define ULONG_MAX       (~0UL)
  34 #define LLONG_MAX       ((long long)(~0ULL>>1))
  35 #define LLONG_MIN       (-LLONG_MAX - 1)
  36 #define ULLONG_MAX      (~0ULL)
  37
  38 #define STACK_MAGIC     0xdeadbeef
  39
  40 #define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
  41 #define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
  42 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  43 #define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  44
  45 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  46
  47 /*
  48  * This looks more complex than it should be. But we need to
  49  * get the type for the ~ right in round_down (it needs to be
  50  * as wide as the result!), and we want to evaluate the macro
  51  * arguments just once each.
  52  */
  53 #define __round_mask(x, y) ((__typeof__(x))((y)-1))
  54 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
  55 #define round_down(x, y) ((x) & ~__round_mask(x, y))
  56
  57 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  58 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  59
  60 /* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
  61 #define roundup(x, y) (                                 \
  62 {                                                       \
  63         const typeof(y) __y = y;                        \
  64         (((x) + (__y - 1)) / __y) * __y;                \
  65 }                                                       \
  66 )
  67 #define rounddown(x, y) (                               \
  68 {                                                       \
  69         typeof(x) __x = (x);                            \
  70         __x - (__x % (y));                              \
  71 }                                                       \
  72 )
  73 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
  74 {                                                       \
  75         typeof(divisor) __divisor = divisor;            \
  76         (((x) + ((__divisor) / 2)) / (__divisor));      \
  77 }                                                       \
  78 )
  79
  80 #define _RET_IP_                (unsigned long)__builtin_return_address(0)
  81 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
  82
  83 #ifdef CONFIG_LBDAF
  84 # include <asm/div64.h>
  85 # define sector_div(a, b) do_div(a, b)
  86 #else
  87 # define sector_div(n, b)( \
  88 { \
  89         int _res; \
  90         _res = (n) % (b); \
  91         (n) /= (b); \
  92         _res; \
  93 } \
  94 )
  95 #endif
  96
  97 /**
  98  * upper_32_bits - return bits 32-63 of a number
  99  * @n: the number we're accessing
 100  *
 101  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 102  * the "right shift count >= width of type" warning when that quantity is
 103  * 32-bits.
 104  */
 105 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 106
 107 /**
 108  * lower_32_bits - return bits 0-31 of a number
 109  * @n: the number we're accessing
 110  */
 111 #define lower_32_bits(n) ((u32)(n))
 112
 113 struct completion;
 114 struct pt_regs;
 115 struct user;
 116
 117 #ifdef CONFIG_PREEMPT_VOLUNTARY
 118 extern int _cond_resched(void);
 119 # define might_resched() _cond_resched()
 120 #else
 121 # define might_resched() do { } while (0)
 122 #endif
 123
 124 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 125   void __might_sleep(const char *file, int line, int preempt_offset);
 126 /**
 127  * might_sleep - annotation for functions that can sleep
 128  *
 129  * this macro will print a stack trace if it is executed in an atomic
 130  * context (spinlock, irq-handler, ...).
 131  *
 132  * This is a useful debugging help to be able to catch problems early and not
 133  * be bitten later when the calling function happens to sleep when it is not
 134  * supposed to.
 135  */
 136 # define might_sleep() \
 137         do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 138 #else
 139   static inline void __might_sleep(const char *file, int line,
 140                                    int preempt_offset) { }
 141 # define might_sleep() do { might_resched(); } while (0)
 142 #endif
 143
 144 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 145
 146 /*
 147  * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
 148  * input types abs() returns a signed long.
 149  * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 150  * for those.
 151  */
 152 #define abs(x) ({                                               \
 153                 long ret;                                       \
 154                 if (sizeof(x) == sizeof(long)) {                \
 155                         long __x = (x);                         \
 156                         ret = (__x < 0) ? -__x : __x;           \
 157                 } else {                                        \
 158                         int __x = (x);                          \
 159                         ret = (__x < 0) ? -__x : __x;           \
 160                 }                                               \
 161                 ret;                                            \
 162         })
 163
 164 #define abs64(x) ({                             \
 165                 s64 __x = (x);                  \
 166                 (__x < 0) ? -__x : __x;         \
 167         })
 168
 169 #ifdef CONFIG_PROVE_LOCKING
 170 void might_fault(void);
 171 #else
 172 static inline void might_fault(void)
 173 {
 174         might_sleep();
 175 }
 176 #endif
 177
 178 extern struct atomic_notifier_head panic_notifier_list;
 179 extern long (*panic_blink)(int state);
 180 NORET_TYPE void panic(const char * fmt, ...)
 181         __attribute__ ((NORET_AND format (printf, 1, 2))) __cold;
 182 extern void oops_enter(void);
 183 extern void oops_exit(void);
 184 void print_oops_end_marker(void);
 185 extern int oops_may_print(void);
 186 NORET_TYPE void do_exit(long error_code)
 187         ATTRIB_NORET;
 188 NORET_TYPE void complete_and_exit(struct completion *, long)
 189         ATTRIB_NORET;
 190
 191 /* Internal, do not use. */
 192 int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 193 int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 194
 195 int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 196 int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 197 static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 198 {
 199         /*
 200          * We want to shortcut function call, but
 201          * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 202          */
 203         if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 204             __alignof__(unsigned long) == __alignof__(unsigned long long))
 205                 return kstrtoull(s, base, (unsigned long long *)res);
 206         else
 207                 return _kstrtoul(s, base, res);
 208 }
 209
 210 static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 211 {
 212         /*
 213          * We want to shortcut function call, but
 214          * __builtin_types_compatible_p(long, long long) = 0.
 215          */
 216         if (sizeof(long) == sizeof(long long) &&
 217             __alignof__(long) == __alignof__(long long))
 218                 return kstrtoll(s, base, (long long *)res);
 219         else
 220                 return _kstrtol(s, base, res);
 221 }
 222
 223 int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 224 int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 225
 226 static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 227 {
 228         return kstrtoull(s, base, res);
 229 }
 230
 231 static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 232 {
 233         return kstrtoll(s, base, res);
 234 }
 235
 236 static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 237 {
 238         return kstrtouint(s, base, res);
 239 }
 240
 241 static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 242 {
 243         return kstrtoint(s, base, res);
 244 }
 245
 246 int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 247 int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 248 int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 249 int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 250
 251 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 252 extern long simple_strtol(const char *,char **,unsigned int);
 253 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 254 extern long long simple_strtoll(const char *,char **,unsigned int);
 255 #define strict_strtoul  kstrtoul
 256 #define strict_strtol   kstrtol
 257 #define strict_strtoull kstrtoull
 258 #define strict_strtoll  kstrtoll
 259
 260 extern int sprintf(char * buf, const char * fmt, ...)
 261         __attribute__ ((format (printf, 2, 3)));
 262 extern int vsprintf(char *buf, const char *, va_list)
 263         __attribute__ ((format (printf, 2, 0)));
 264 extern int snprintf(char * buf, size_t size, const char * fmt, ...)
 265         __attribute__ ((format (printf, 3, 4)));
 266 extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 267         __attribute__ ((format (printf, 3, 0)));
 268 extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
 269         __attribute__ ((format (printf, 3, 4)));
 270 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 271         __attribute__ ((format (printf, 3, 0)));
 272 extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
 273         __attribute__ ((format (printf, 2, 3)));
 274 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 275
 276 extern int sscanf(const char *, const char *, ...)
 277         __attribute__ ((format (scanf, 2, 3)));
 278 extern int vsscanf(const char *, const char *, va_list)
 279         __attribute__ ((format (scanf, 2, 0)));
 280
 281 extern int get_option(char **str, int *pint);
 282 extern char *get_options(const char *str, int nints, int *ints);
 283 extern unsigned long long memparse(const char *ptr, char **retptr);
 284
 285 extern int core_kernel_text(unsigned long addr);
 286 extern int core_kernel_data(unsigned long addr);
 287 extern int __kernel_text_address(unsigned long addr);
 288 extern int kernel_text_address(unsigned long addr);
 289 extern int func_ptr_is_kernel_text(void *ptr);
 290
 291 struct pid;
 292 extern struct pid *session_of_pgrp(struct pid *pgrp);
 293
 294 unsigned long int_sqrt(unsigned long);
 295
 296 extern void bust_spinlocks(int yes);
 297 extern void wake_up_klogd(void);
 298 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 299 extern int panic_timeout;
 300 extern int panic_on_oops;
 301 extern int panic_on_unrecovered_nmi;
 302 extern int panic_on_io_nmi;
 303 extern const char *print_tainted(void);
 304 extern void add_taint(unsigned flag);
 305 extern int test_taint(unsigned flag);
 306 extern unsigned long get_taint(void);
 307 extern int root_mountflags;
 308
 309 extern bool early_boot_irqs_disabled;
 310
 311 /* Values used for system_state */
 312 extern enum system_states {
 313         SYSTEM_BOOTING,
 314         SYSTEM_RUNNING,
 315         SYSTEM_HALT,
 316         SYSTEM_POWER_OFF,
 317         SYSTEM_RESTART,
 318         SYSTEM_SUSPEND_DISK,
 319 } system_state;
 320
 321 #define TAINT_PROPRIETARY_MODULE        0
 322 #define TAINT_FORCED_MODULE             1
 323 #define TAINT_UNSAFE_SMP                2
 324 #define TAINT_FORCED_RMMOD              3
 325 #define TAINT_MACHINE_CHECK             4
 326 #define TAINT_BAD_PAGE                  5
 327 #define TAINT_USER                      6
 328 #define TAINT_DIE                       7
 329 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
 330 #define TAINT_WARN                      9
 331 #define TAINT_CRAP                      10
 332 #define TAINT_FIRMWARE_WORKAROUND       11
 333
 334 extern const char hex_asc[];
 335 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 336 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 337
 338 static inline char *pack_hex_byte(char *buf, u8 byte)
 339 {
 340         *buf++ = hex_asc_hi(byte);
 341         *buf++ = hex_asc_lo(byte);
 342         return buf;
 343 }
 344
 345 extern int hex_to_bin(char ch);
 346 extern void hex2bin(u8 *dst, const char *src, size_t count);
 347
 348 /*
 349  * General tracing related utility functions - trace_printk(),
 350  * tracing_on/tracing_off and tracing_start()/tracing_stop
 351  *
 352  * Use tracing_on/tracing_off when you want to quickly turn on or off
 353  * tracing. It simply enables or disables the recording of the trace events.
 354  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 355  * file, which gives a means for the kernel and userspace to interact.
 356  * Place a tracing_off() in the kernel where you want tracing to end.
 357  * From user space, examine the trace, and then echo 1 > tracing_on
 358  * to continue tracing.
 359  *
 360  * tracing_stop/tracing_start has slightly more overhead. It is used
 361  * by things like suspend to ram where disabling the recording of the
 362  * trace is not enough, but tracing must actually stop because things
 363  * like calling smp_processor_id() may crash the system.
 364  *
 365  * Most likely, you want to use tracing_on/tracing_off.
 366  */
 367 #ifdef CONFIG_RING_BUFFER
 368 void tracing_on(void);
 369 void tracing_off(void);
 370 /* trace_off_permanent stops recording with no way to bring it back */
 371 void tracing_off_permanent(void);
 372 int tracing_is_on(void);
 373 #else
 374 static inline void tracing_on(void) { }
 375 static inline void tracing_off(void) { }
 376 static inline void tracing_off_permanent(void) { }
 377 static inline int tracing_is_on(void) { return 0; }
 378 #endif
 379
 380 enum ftrace_dump_mode {
 381         DUMP_NONE,
 382         DUMP_ALL,
 383         DUMP_ORIG,
 384 };
 385
 386 #ifdef CONFIG_TRACING
 387 extern void tracing_start(void);
 388 extern void tracing_stop(void);
 389 extern void ftrace_off_permanent(void);
 390
 391 static inline void __attribute__ ((format (printf, 1, 2)))
 392 ____trace_printk_check_format(const char *fmt, ...)
 393 {
 394 }
 395 #define __trace_printk_check_format(fmt, args...)                       \
 396 do {                                                                    \
 397         if (0)                                                          \
 398                 ____trace_printk_check_format(fmt, ##args);             \
 399 } while (0)
 400
 401 /**
 402  * trace_printk - printf formatting in the ftrace buffer
 403  * @fmt: the printf format for printing
 404  *
 405  * Note: __trace_printk is an internal function for trace_printk and
 406  *       the @ip is passed in via the trace_printk macro.
 407  *
 408  * This function allows a kernel developer to debug fast path sections
 409  * that printk is not appropriate for. By scattering in various
 410  * printk like tracing in the code, a developer can quickly see
 411  * where problems are occurring.
 412  *
 413  * This is intended as a debugging tool for the developer only.
 414  * Please refrain from leaving trace_printks scattered around in
 415  * your code.
 416  */
 417
 418 #define trace_printk(fmt, args...)                                      \
 419 do {                                                                    \
 420         __trace_printk_check_format(fmt, ##args);                       \
 421         if (__builtin_constant_p(fmt)) {                                \
 422                 static const char *trace_printk_fmt                     \
 423                   __attribute__((section("__trace_printk_fmt"))) =      \
 424                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 425                                                                         \
 426                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 427         } else                                                          \
 428                 __trace_printk(_THIS_IP_, fmt, ##args);         \
 429 } while (0)
 430
 431 extern int
 432 __trace_bprintk(unsigned long ip, const char *fmt, ...)
 433         __attribute__ ((format (printf, 2, 3)));
 434
 435 extern int
 436 __trace_printk(unsigned long ip, const char *fmt, ...)
 437         __attribute__ ((format (printf, 2, 3)));
 438
 439 extern void trace_dump_stack(void);
 440
 441 /*
 442  * The double __builtin_constant_p is because gcc will give us an error
 443  * if we try to allocate the static variable to fmt if it is not a
 444  * constant. Even with the outer if statement.
 445  */
 446 #define ftrace_vprintk(fmt, vargs)                                      \
 447 do {                                                                    \
 448         if (__builtin_constant_p(fmt)) {                                \
 449                 static const char *trace_printk_fmt                     \
 450                   __attribute__((section("__trace_printk_fmt"))) =      \
 451                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 452                                                                         \
 453                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 454         } else                                                          \
 455                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 456 } while (0)
 457
 458 extern int
 459 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 460
 461 extern int
 462 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 463
 464 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 465 #else
 466 static inline int
 467 trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 468
 469 static inline void tracing_start(void) { }
 470 static inline void tracing_stop(void) { }
 471 static inline void ftrace_off_permanent(void) { }
 472 static inline void trace_dump_stack(void) { }
 473 static inline int
 474 trace_printk(const char *fmt, ...)
 475 {
 476         return 0;
 477 }
 478 static inline int
 479 ftrace_vprintk(const char *fmt, va_list ap)
 480 {
 481         return 0;
 482 }
 483 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 484 #endif /* CONFIG_TRACING */
 485
 486 /*
 487  * min()/max()/clamp() macros that also do
 488  * strict type-checking.. See the
 489  * "unnecessary" pointer comparison.
 490  */
 491 #define min(x, y) ({                            \
 492         typeof(x) _min1 = (x);                  \
 493         typeof(y) _min2 = (y);                  \
 494         (void) (&_min1 == &_min2);              \
 495         _min1 < _min2 ? _min1 : _min2; })
 496
 497 #define max(x, y) ({                            \
 498         typeof(x) _max1 = (x);                  \
 499         typeof(y) _max2 = (y);                  \
 500         (void) (&_max1 == &_max2);              \
 501         _max1 > _max2 ? _max1 : _max2; })
 502
 503 #define min3(x, y, z) ({                        \
 504         typeof(x) _min1 = (x);                  \
 505         typeof(y) _min2 = (y);                  \
 506         typeof(z) _min3 = (z);                  \
 507         (void) (&_min1 == &_min2);              \
 508         (void) (&_min1 == &_min3);              \
 509         _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
 510                 (_min2 < _min3 ? _min2 : _min3); })
 511
 512 #define max3(x, y, z) ({                        \
 513         typeof(x) _max1 = (x);                  \
 514         typeof(y) _max2 = (y);                  \
 515         typeof(z) _max3 = (z);                  \
 516         (void) (&_max1 == &_max2);              \
 517         (void) (&_max1 == &_max3);              \
 518         _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
 519                 (_max2 > _max3 ? _max2 : _max3); })
 520
 521 /**
 522  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 523  * @x: value1
 524  * @y: value2
 525  */
 526 #define min_not_zero(x, y) ({                   \
 527         typeof(x) __x = (x);                    \
 528         typeof(y) __y = (y);                    \
 529         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 530
 531 /**
 532  * clamp - return a value clamped to a given range with strict typechecking
 533  * @val: current value
 534  * @min: minimum allowable value
 535  * @max: maximum allowable value
 536  *
 537  * This macro does strict typechecking of min/max to make sure they are of the
 538  * same type as val.  See the unnecessary pointer comparisons.
 539  */
 540 #define clamp(val, min, max) ({                 \
 541         typeof(val) __val = (val);              \
 542         typeof(min) __min = (min);              \
 543         typeof(max) __max = (max);              \
 544         (void) (&__val == &__min);              \
 545         (void) (&__val == &__max);              \
 546         __val = __val < __min ? __min: __val;   \
 547         __val > __max ? __max: __val; })
 548
 549 /*
 550  * ..and if you can't take the strict
 551  * types, you can specify one yourself.
 552  *
 553  * Or not use min/max/clamp at all, of course.
 554  */
 555 #define min_t(type, x, y) ({                    \
 556         type __min1 = (x);                      \
 557         type __min2 = (y);                      \
 558         __min1 < __min2 ? __min1: __min2; })
 559
 560 #define max_t(type, x, y) ({                    \
 561         type __max1 = (x);                      \
 562         type __max2 = (y);                      \
 563         __max1 > __max2 ? __max1: __max2; })
 564
 565 /**
 566  * clamp_t - return a value clamped to a given range using a given type
 567  * @type: the type of variable to use
 568  * @val: current value
 569  * @min: minimum allowable value
 570  * @max: maximum allowable value
 571  *
 572  * This macro does no typechecking and uses temporary variables of type
 573  * 'type' to make all the comparisons.
 574  */
 575 #define clamp_t(type, val, min, max) ({         \
 576         type __val = (val);                     \
 577         type __min = (min);                     \
 578         type __max = (max);                     \
 579         __val = __val < __min ? __min: __val;   \
 580         __val > __max ? __max: __val; })
 581
 582 /**
 583  * clamp_val - return a value clamped to a given range using val's type
 584  * @val: current value
 585  * @min: minimum allowable value
 586  * @max: maximum allowable value
 587  *
 588  * This macro does no typechecking and uses temporary variables of whatever
 589  * type the input argument 'val' is.  This is useful when val is an unsigned
 590  * type and min and max are literals that will otherwise be assigned a signed
 591  * integer type.
 592  */
 593 #define clamp_val(val, min, max) ({             \
 594         typeof(val) __val = (val);              \
 595         typeof(val) __min = (min);              \
 596         typeof(val) __max = (max);              \
 597         __val = __val < __min ? __min: __val;   \
 598         __val > __max ? __max: __val; })
 599
 600
 601 /*
 602  * swap - swap value of @a and @b
 603  */
 604 #define swap(a, b) \
 605         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 606
 607 /**
 608  * container_of - cast a member of a structure out to the containing structure
 609  * @ptr:        the pointer to the member.
 610  * @type:       the type of the container struct this is embedded in.
 611  * @member:     the name of the member within the struct.
 612  *
 613  */
 614 #define container_of(ptr, type, member) ({                      \
 615         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 616         (type *)( (char *)__mptr - offsetof(type,member) );})
 617
 618 struct sysinfo;
 619 extern int do_sysinfo(struct sysinfo *info);
 620
 621 #endif /* __KERNEL__ */
 622
 623 #define SI_LOAD_SHIFT   16
 624 struct sysinfo {
 625         long uptime;                    /* Seconds since boot */
 626         unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
 627         unsigned long totalram;         /* Total usable main memory size */
 628         unsigned long freeram;          /* Available memory size */
 629         unsigned long sharedram;        /* Amount of shared memory */
 630         unsigned long bufferram;        /* Memory used by buffers */
 631         unsigned long totalswap;        /* Total swap space size */
 632         unsigned long freeswap;         /* swap space still available */
 633         unsigned short procs;           /* Number of current processes */
 634         unsigned short pad;             /* explicit padding for m68k */
 635         unsigned long totalhigh;        /* Total high memory size */
 636         unsigned long freehigh;         /* Available high memory size */
 637         unsigned int mem_unit;          /* Memory unit size in bytes */
 638         char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
 639 };
 640
 641 /* Force a compilation error if a constant expression is not a power of 2 */
 642 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)                  \
 643         BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
 644
 645 /* Force a compilation error if condition is true, but also produce a
 646    result (of value 0 and type size_t), so the expression can be used
 647    e.g. in a structure initializer (or where-ever else comma expressions
 648    aren't permitted). */
 649 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 650 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 651
 652 /**
 653  * BUILD_BUG_ON - break compile if a condition is true.
 654  * @condition: the condition which the compiler should know is false.
 655  *
 656  * If you have some code which relies on certain constants being equal, or
 657  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
 658  * detect if someone changes it.
 659  *
 660  * The implementation uses gcc's reluctance to create a negative array, but
 661  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
 662  * to inline functions).  So as a fallback we use the optimizer; if it can't
 663  * prove the condition is false, it will cause a link error on the undefined
 664  * "__build_bug_on_failed".  This error message can be harder to track down
 665  * though, hence the two different methods.
 666  */
 667 #ifndef __OPTIMIZE__
 668 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 669 #else
 670 extern int __build_bug_on_failed;
 671 #define BUILD_BUG_ON(condition)                                 \
 672         do {                                                    \
 673                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
 674                 if (condition) __build_bug_on_failed = 1;       \
 675         } while(0)
 676 #endif
 677
 678 /* Trap pasters of __FUNCTION__ at compile-time */
 679 #define __FUNCTION__ (__func__)
 680
 681 /* This helps us to avoid #ifdef CONFIG_NUMA */
 682 #ifdef CONFIG_NUMA
 683 #define NUMA_BUILD 1
 684 #else
 685 #define NUMA_BUILD 0
 686 #endif
 687
 688 /* This helps us avoid #ifdef CONFIG_COMPACTION */
 689 #ifdef CONFIG_COMPACTION
 690 #define COMPACTION_BUILD 1
 691 #else
 692 #define COMPACTION_BUILD 0
 693 #endif
 694
 695 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 696 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 697 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 698 #endif
 699
 700 #endif