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 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 191 extern long simple_strtol(const char *,char **,unsigned int);
 192 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 193 extern long long simple_strtoll(const char *,char **,unsigned int);
 194 extern int __must_check strict_strtoul(const char *, unsigned int, unsigned long *);
 195 extern int __must_check strict_strtol(const char *, unsigned int, long *);
 196 extern int __must_check strict_strtoull(const char *, unsigned int, unsigned long long *);
 197 extern int __must_check strict_strtoll(const char *, unsigned int, long long *);
 198 extern int sprintf(char * buf, const char * fmt, ...)
 199         __attribute__ ((format (printf, 2, 3)));
 200 extern int vsprintf(char *buf, const char *, va_list)
 201         __attribute__ ((format (printf, 2, 0)));
 202 extern int snprintf(char * buf, size_t size, const char * fmt, ...)
 203         __attribute__ ((format (printf, 3, 4)));
 204 extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 205         __attribute__ ((format (printf, 3, 0)));
 206 extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
 207         __attribute__ ((format (printf, 3, 4)));
 208 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 209         __attribute__ ((format (printf, 3, 0)));
 210 extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
 211         __attribute__ ((format (printf, 2, 3)));
 212 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 213
 214 extern int sscanf(const char *, const char *, ...)
 215         __attribute__ ((format (scanf, 2, 3)));
 216 extern int vsscanf(const char *, const char *, va_list)
 217         __attribute__ ((format (scanf, 2, 0)));
 218
 219 extern int get_option(char **str, int *pint);
 220 extern char *get_options(const char *str, int nints, int *ints);
 221 extern unsigned long long memparse(const char *ptr, char **retptr);
 222
 223 extern int core_kernel_text(unsigned long addr);
 224 extern int __kernel_text_address(unsigned long addr);
 225 extern int kernel_text_address(unsigned long addr);
 226 extern int func_ptr_is_kernel_text(void *ptr);
 227
 228 struct pid;
 229 extern struct pid *session_of_pgrp(struct pid *pgrp);
 230
 231 unsigned long int_sqrt(unsigned long);
 232
 233 extern void bust_spinlocks(int yes);
 234 extern void wake_up_klogd(void);
 235 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 236 extern int panic_timeout;
 237 extern int panic_on_oops;
 238 extern int panic_on_unrecovered_nmi;
 239 extern int panic_on_io_nmi;
 240 extern const char *print_tainted(void);
 241 extern void add_taint(unsigned flag);
 242 extern int test_taint(unsigned flag);
 243 extern unsigned long get_taint(void);
 244 extern int root_mountflags;
 245
 246 extern bool early_boot_irqs_disabled;
 247
 248 /* Values used for system_state */
 249 extern enum system_states {
 250         SYSTEM_BOOTING,
 251         SYSTEM_RUNNING,
 252         SYSTEM_HALT,
 253         SYSTEM_POWER_OFF,
 254         SYSTEM_RESTART,
 255         SYSTEM_SUSPEND_DISK,
 256 } system_state;
 257
 258 #define TAINT_PROPRIETARY_MODULE        0
 259 #define TAINT_FORCED_MODULE             1
 260 #define TAINT_UNSAFE_SMP                2
 261 #define TAINT_FORCED_RMMOD              3
 262 #define TAINT_MACHINE_CHECK             4
 263 #define TAINT_BAD_PAGE                  5
 264 #define TAINT_USER                      6
 265 #define TAINT_DIE                       7
 266 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
 267 #define TAINT_WARN                      9
 268 #define TAINT_CRAP                      10
 269 #define TAINT_FIRMWARE_WORKAROUND       11
 270
 271 extern const char hex_asc[];
 272 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 273 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 274
 275 static inline char *pack_hex_byte(char *buf, u8 byte)
 276 {
 277         *buf++ = hex_asc_hi(byte);
 278         *buf++ = hex_asc_lo(byte);
 279         return buf;
 280 }
 281
 282 extern int hex_to_bin(char ch);
 283 extern void hex2bin(u8 *dst, const char *src, size_t count);
 284
 285 /*
 286  * General tracing related utility functions - trace_printk(),
 287  * tracing_on/tracing_off and tracing_start()/tracing_stop
 288  *
 289  * Use tracing_on/tracing_off when you want to quickly turn on or off
 290  * tracing. It simply enables or disables the recording of the trace events.
 291  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 292  * file, which gives a means for the kernel and userspace to interact.
 293  * Place a tracing_off() in the kernel where you want tracing to end.
 294  * From user space, examine the trace, and then echo 1 > tracing_on
 295  * to continue tracing.
 296  *
 297  * tracing_stop/tracing_start has slightly more overhead. It is used
 298  * by things like suspend to ram where disabling the recording of the
 299  * trace is not enough, but tracing must actually stop because things
 300  * like calling smp_processor_id() may crash the system.
 301  *
 302  * Most likely, you want to use tracing_on/tracing_off.
 303  */
 304 #ifdef CONFIG_RING_BUFFER
 305 void tracing_on(void);
 306 void tracing_off(void);
 307 /* trace_off_permanent stops recording with no way to bring it back */
 308 void tracing_off_permanent(void);
 309 int tracing_is_on(void);
 310 #else
 311 static inline void tracing_on(void) { }
 312 static inline void tracing_off(void) { }
 313 static inline void tracing_off_permanent(void) { }
 314 static inline int tracing_is_on(void) { return 0; }
 315 #endif
 316
 317 enum ftrace_dump_mode {
 318         DUMP_NONE,
 319         DUMP_ALL,
 320         DUMP_ORIG,
 321 };
 322
 323 #ifdef CONFIG_TRACING
 324 extern void tracing_start(void);
 325 extern void tracing_stop(void);
 326 extern void ftrace_off_permanent(void);
 327
 328 static inline void __attribute__ ((format (printf, 1, 2)))
 329 ____trace_printk_check_format(const char *fmt, ...)
 330 {
 331 }
 332 #define __trace_printk_check_format(fmt, args...)                       \
 333 do {                                                                    \
 334         if (0)                                                          \
 335                 ____trace_printk_check_format(fmt, ##args);             \
 336 } while (0)
 337
 338 /**
 339  * trace_printk - printf formatting in the ftrace buffer
 340  * @fmt: the printf format for printing
 341  *
 342  * Note: __trace_printk is an internal function for trace_printk and
 343  *       the @ip is passed in via the trace_printk macro.
 344  *
 345  * This function allows a kernel developer to debug fast path sections
 346  * that printk is not appropriate for. By scattering in various
 347  * printk like tracing in the code, a developer can quickly see
 348  * where problems are occurring.
 349  *
 350  * This is intended as a debugging tool for the developer only.
 351  * Please refrain from leaving trace_printks scattered around in
 352  * your code.
 353  */
 354
 355 #define trace_printk(fmt, args...)                                      \
 356 do {                                                                    \
 357         __trace_printk_check_format(fmt, ##args);                       \
 358         if (__builtin_constant_p(fmt)) {                                \
 359                 static const char *trace_printk_fmt                     \
 360                   __attribute__((section("__trace_printk_fmt"))) =      \
 361                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 362                                                                         \
 363                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 364         } else                                                          \
 365                 __trace_printk(_THIS_IP_, fmt, ##args);         \
 366 } while (0)
 367
 368 extern int
 369 __trace_bprintk(unsigned long ip, const char *fmt, ...)
 370         __attribute__ ((format (printf, 2, 3)));
 371
 372 extern int
 373 __trace_printk(unsigned long ip, const char *fmt, ...)
 374         __attribute__ ((format (printf, 2, 3)));
 375
 376 extern void trace_dump_stack(void);
 377
 378 /*
 379  * The double __builtin_constant_p is because gcc will give us an error
 380  * if we try to allocate the static variable to fmt if it is not a
 381  * constant. Even with the outer if statement.
 382  */
 383 #define ftrace_vprintk(fmt, vargs)                                      \
 384 do {                                                                    \
 385         if (__builtin_constant_p(fmt)) {                                \
 386                 static const char *trace_printk_fmt                     \
 387                   __attribute__((section("__trace_printk_fmt"))) =      \
 388                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 389                                                                         \
 390                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 391         } else                                                          \
 392                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 393 } while (0)
 394
 395 extern int
 396 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 397
 398 extern int
 399 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 400
 401 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 402 #else
 403 static inline int
 404 trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 405
 406 static inline void tracing_start(void) { }
 407 static inline void tracing_stop(void) { }
 408 static inline void ftrace_off_permanent(void) { }
 409 static inline void trace_dump_stack(void) { }
 410 static inline int
 411 trace_printk(const char *fmt, ...)
 412 {
 413         return 0;
 414 }
 415 static inline int
 416 ftrace_vprintk(const char *fmt, va_list ap)
 417 {
 418         return 0;
 419 }
 420 static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 421 #endif /* CONFIG_TRACING */
 422
 423 /*
 424  * min()/max()/clamp() macros that also do
 425  * strict type-checking.. See the
 426  * "unnecessary" pointer comparison.
 427  */
 428 #define min(x, y) ({                            \
 429         typeof(x) _min1 = (x);                  \
 430         typeof(y) _min2 = (y);                  \
 431         (void) (&_min1 == &_min2);              \
 432         _min1 < _min2 ? _min1 : _min2; })
 433
 434 #define max(x, y) ({                            \
 435         typeof(x) _max1 = (x);                  \
 436         typeof(y) _max2 = (y);                  \
 437         (void) (&_max1 == &_max2);              \
 438         _max1 > _max2 ? _max1 : _max2; })
 439
 440 #define min3(x, y, z) ({                        \
 441         typeof(x) _min1 = (x);                  \
 442         typeof(y) _min2 = (y);                  \
 443         typeof(z) _min3 = (z);                  \
 444         (void) (&_min1 == &_min2);              \
 445         (void) (&_min1 == &_min3);              \
 446         _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
 447                 (_min2 < _min3 ? _min2 : _min3); })
 448
 449 #define max3(x, y, z) ({                        \
 450         typeof(x) _max1 = (x);                  \
 451         typeof(y) _max2 = (y);                  \
 452         typeof(z) _max3 = (z);                  \
 453         (void) (&_max1 == &_max2);              \
 454         (void) (&_max1 == &_max3);              \
 455         _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
 456                 (_max2 > _max3 ? _max2 : _max3); })
 457
 458 /**
 459  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 460  * @x: value1
 461  * @y: value2
 462  */
 463 #define min_not_zero(x, y) ({                   \
 464         typeof(x) __x = (x);                    \
 465         typeof(y) __y = (y);                    \
 466         __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 467
 468 /**
 469  * clamp - return a value clamped to a given range with strict typechecking
 470  * @val: current value
 471  * @min: minimum allowable value
 472  * @max: maximum allowable value
 473  *
 474  * This macro does strict typechecking of min/max to make sure they are of the
 475  * same type as val.  See the unnecessary pointer comparisons.
 476  */
 477 #define clamp(val, min, max) ({                 \
 478         typeof(val) __val = (val);              \
 479         typeof(min) __min = (min);              \
 480         typeof(max) __max = (max);              \
 481         (void) (&__val == &__min);              \
 482         (void) (&__val == &__max);              \
 483         __val = __val < __min ? __min: __val;   \
 484         __val > __max ? __max: __val; })
 485
 486 /*
 487  * ..and if you can't take the strict
 488  * types, you can specify one yourself.
 489  *
 490  * Or not use min/max/clamp at all, of course.
 491  */
 492 #define min_t(type, x, y) ({                    \
 493         type __min1 = (x);                      \
 494         type __min2 = (y);                      \
 495         __min1 < __min2 ? __min1: __min2; })
 496
 497 #define max_t(type, x, y) ({                    \
 498         type __max1 = (x);                      \
 499         type __max2 = (y);                      \
 500         __max1 > __max2 ? __max1: __max2; })
 501
 502 /**
 503  * clamp_t - return a value clamped to a given range using a given type
 504  * @type: the type of variable to use
 505  * @val: current value
 506  * @min: minimum allowable value
 507  * @max: maximum allowable value
 508  *
 509  * This macro does no typechecking and uses temporary variables of type
 510  * 'type' to make all the comparisons.
 511  */
 512 #define clamp_t(type, val, min, max) ({         \
 513         type __val = (val);                     \
 514         type __min = (min);                     \
 515         type __max = (max);                     \
 516         __val = __val < __min ? __min: __val;   \
 517         __val > __max ? __max: __val; })
 518
 519 /**
 520  * clamp_val - return a value clamped to a given range using val's type
 521  * @val: current value
 522  * @min: minimum allowable value
 523  * @max: maximum allowable value
 524  *
 525  * This macro does no typechecking and uses temporary variables of whatever
 526  * type the input argument 'val' is.  This is useful when val is an unsigned
 527  * type and min and max are literals that will otherwise be assigned a signed
 528  * integer type.
 529  */
 530 #define clamp_val(val, min, max) ({             \
 531         typeof(val) __val = (val);              \
 532         typeof(val) __min = (min);              \
 533         typeof(val) __max = (max);              \
 534         __val = __val < __min ? __min: __val;   \
 535         __val > __max ? __max: __val; })
 536
 537
 538 /*
 539  * swap - swap value of @a and @b
 540  */
 541 #define swap(a, b) \
 542         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 543
 544 /**
 545  * container_of - cast a member of a structure out to the containing structure
 546  * @ptr:        the pointer to the member.
 547  * @type:       the type of the container struct this is embedded in.
 548  * @member:     the name of the member within the struct.
 549  *
 550  */
 551 #define container_of(ptr, type, member) ({                      \
 552         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 553         (type *)( (char *)__mptr - offsetof(type,member) );})
 554
 555 struct sysinfo;
 556 extern int do_sysinfo(struct sysinfo *info);
 557
 558 #endif /* __KERNEL__ */
 559
 560 #define SI_LOAD_SHIFT   16
 561 struct sysinfo {
 562         long uptime;                    /* Seconds since boot */
 563         unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
 564         unsigned long totalram;         /* Total usable main memory size */
 565         unsigned long freeram;          /* Available memory size */
 566         unsigned long sharedram;        /* Amount of shared memory */
 567         unsigned long bufferram;        /* Memory used by buffers */
 568         unsigned long totalswap;        /* Total swap space size */
 569         unsigned long freeswap;         /* swap space still available */
 570         unsigned short procs;           /* Number of current processes */
 571         unsigned short pad;             /* explicit padding for m68k */
 572         unsigned long totalhigh;        /* Total high memory size */
 573         unsigned long freehigh;         /* Available high memory size */
 574         unsigned int mem_unit;          /* Memory unit size in bytes */
 575         char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
 576 };
 577
 578 /* Force a compilation error if condition is true */
 579 #define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
 580
 581 /* Force a compilation error if condition is constant and true */
 582 #define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
 583
 584 /* Force a compilation error if a constant expression is not a power of 2 */
 585 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)                  \
 586         BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
 587
 588 /* Force a compilation error if condition is true, but also produce a
 589    result (of value 0 and type size_t), so the expression can be used
 590    e.g. in a structure initializer (or where-ever else comma expressions
 591    aren't permitted). */
 592 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 593 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 594
 595 /* Trap pasters of __FUNCTION__ at compile-time */
 596 #define __FUNCTION__ (__func__)
 597
 598 /* This helps us to avoid #ifdef CONFIG_NUMA */
 599 #ifdef CONFIG_NUMA
 600 #define NUMA_BUILD 1
 601 #else
 602 #define NUMA_BUILD 0
 603 #endif
 604
 605 /* This helps us avoid #ifdef CONFIG_COMPACTION */
 606 #ifdef CONFIG_COMPACTION
 607 #define COMPACTION_BUILD 1
 608 #else
 609 #define COMPACTION_BUILD 0
 610 #endif
 611
 612 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 613 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 614 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 615 #endif
 616
 617 #endif