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
   8 #ifdef __KERNEL__
   9
  10 #include <stdarg.h>
  11 #include <linux/linkage.h>
  12 #include <linux/stddef.h>
  13 #include <linux/types.h>
  14 #include <linux/compiler.h>
  15 #include <linux/bitops.h>
  16 #include <linux/log2.h>
  17 #include <linux/typecheck.h>
  18 #include <linux/dynamic_debug.h>
  19 #include <asm/byteorder.h>
  20 #include <asm/bug.h>
  21
  22 extern const char linux_banner[];
  23 extern const char linux_proc_banner[];
  24
  25 #define USHORT_MAX      ((u16)(~0U))
  26 #define SHORT_MAX       ((s16)(USHORT_MAX>>1))
  27 #define SHORT_MIN       (-SHORT_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_MASK(x,(typeof(x))(a)-1)
  41 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(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 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  48 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  49 #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
  50 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
  51 {                                                       \
  52         typeof(divisor) __divisor = divisor;            \
  53         (((x) + ((__divisor) / 2)) / (__divisor));      \
  54 }                                                       \
  55 )
  56
  57 #define _RET_IP_                (unsigned long)__builtin_return_address(0)
  58 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
  59
  60 #ifdef CONFIG_LBDAF
  61 # include <asm/div64.h>
  62 # define sector_div(a, b) do_div(a, b)
  63 #else
  64 # define sector_div(n, b)( \
  65 { \
  66         int _res; \
  67         _res = (n) % (b); \
  68         (n) /= (b); \
  69         _res; \
  70 } \
  71 )
  72 #endif
  73
  74 /**
  75  * upper_32_bits - return bits 32-63 of a number
  76  * @n: the number we're accessing
  77  *
  78  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
  79  * the "right shift count >= width of type" warning when that quantity is
  80  * 32-bits.
  81  */
  82 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
  83
  84 /**
  85  * lower_32_bits - return bits 0-31 of a number
  86  * @n: the number we're accessing
  87  */
  88 #define lower_32_bits(n) ((u32)(n))
  89
  90 #define KERN_EMERG      "<0>"   /* system is unusable                   */
  91 #define KERN_ALERT      "<1>"   /* action must be taken immediately     */
  92 #define KERN_CRIT       "<2>"   /* critical conditions                  */
  93 #define KERN_ERR        "<3>"   /* error conditions                     */
  94 #define KERN_WARNING    "<4>"   /* warning conditions                   */
  95 #define KERN_NOTICE     "<5>"   /* normal but significant condition     */
  96 #define KERN_INFO       "<6>"   /* informational                        */
  97 #define KERN_DEBUG      "<7>"   /* debug-level messages                 */
  98
  99 /* Use the default kernel loglevel */
 100 #define KERN_DEFAULT    "<d>"
 101 /*
 102  * Annotation for a "continued" line of log printout (only done after a
 103  * line that had no enclosing \n). Only to be used by core/arch code
 104  * during early bootup (a continued line is not SMP-safe otherwise).
 105  */
 106 #define KERN_CONT       "<c>"
 107
 108 extern int console_printk[];
 109
 110 #define console_loglevel (console_printk[0])
 111 #define default_message_loglevel (console_printk[1])
 112 #define minimum_console_loglevel (console_printk[2])
 113 #define default_console_loglevel (console_printk[3])
 114
 115 struct completion;
 116 struct pt_regs;
 117 struct user;
 118
 119 #ifdef CONFIG_PREEMPT_VOLUNTARY
 120 extern int _cond_resched(void);
 121 # define might_resched() _cond_resched()
 122 #else
 123 # define might_resched() do { } while (0)
 124 #endif
 125
 126 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 127   void __might_sleep(char *file, int line, int preempt_offset);
 128 /**
 129  * might_sleep - annotation for functions that can sleep
 130  *
 131  * this macro will print a stack trace if it is executed in an atomic
 132  * context (spinlock, irq-handler, ...).
 133  *
 134  * This is a useful debugging help to be able to catch problems early and not
 135  * be bitten later when the calling function happens to sleep when it is not
 136  * supposed to.
 137  */
 138 # define might_sleep() \
 139         do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 140 #else
 141   static inline void __might_sleep(char *file, int line, int preempt_offset) { }
 142 # define might_sleep() do { might_resched(); } while (0)
 143 #endif
 144
 145 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 146
 147 #define abs(x) ({                               \
 148                 int __x = (x);                  \
 149                 (__x < 0) ? -__x : __x;         \
 150         })
 151
 152 #ifdef CONFIG_PROVE_LOCKING
 153 void might_fault(void);
 154 #else
 155 static inline void might_fault(void)
 156 {
 157         might_sleep();
 158 }
 159 #endif
 160
 161 extern struct atomic_notifier_head panic_notifier_list;
 162 extern long (*panic_blink)(long time);
 163 NORET_TYPE void panic(const char * fmt, ...)
 164         __attribute__ ((NORET_AND format (printf, 1, 2))) __cold;
 165 extern void oops_enter(void);
 166 extern void oops_exit(void);
 167 extern int oops_may_print(void);
 168 NORET_TYPE void do_exit(long error_code)
 169         ATTRIB_NORET;
 170 NORET_TYPE void complete_and_exit(struct completion *, long)
 171         ATTRIB_NORET;
 172 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 173 extern long simple_strtol(const char *,char **,unsigned int);
 174 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 175 extern long long simple_strtoll(const char *,char **,unsigned int);
 176 extern int strict_strtoul(const char *, unsigned int, unsigned long *);
 177 extern int strict_strtol(const char *, unsigned int, long *);
 178 extern int strict_strtoull(const char *, unsigned int, unsigned long long *);
 179 extern int strict_strtoll(const char *, unsigned int, long long *);
 180 extern int sprintf(char * buf, const char * fmt, ...)
 181         __attribute__ ((format (printf, 2, 3)));
 182 extern int vsprintf(char *buf, const char *, va_list)
 183         __attribute__ ((format (printf, 2, 0)));
 184 extern int snprintf(char * buf, size_t size, const char * fmt, ...)
 185         __attribute__ ((format (printf, 3, 4)));
 186 extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 187         __attribute__ ((format (printf, 3, 0)));
 188 extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
 189         __attribute__ ((format (printf, 3, 4)));
 190 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 191         __attribute__ ((format (printf, 3, 0)));
 192 extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
 193         __attribute__ ((format (printf, 2, 3)));
 194 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 195
 196 extern int sscanf(const char *, const char *, ...)
 197         __attribute__ ((format (scanf, 2, 3)));
 198 extern int vsscanf(const char *, const char *, va_list)
 199         __attribute__ ((format (scanf, 2, 0)));
 200
 201 extern int get_option(char **str, int *pint);
 202 extern char *get_options(const char *str, int nints, int *ints);
 203 extern unsigned long long memparse(const char *ptr, char **retptr);
 204
 205 extern int core_kernel_text(unsigned long addr);
 206 extern int __kernel_text_address(unsigned long addr);
 207 extern int kernel_text_address(unsigned long addr);
 208 extern int func_ptr_is_kernel_text(void *ptr);
 209
 210 struct pid;
 211 extern struct pid *session_of_pgrp(struct pid *pgrp);
 212
 213 /*
 214  * FW_BUG
 215  * Add this to a message where you are sure the firmware is buggy or behaves
 216  * really stupid or out of spec. Be aware that the responsible BIOS developer
 217  * should be able to fix this issue or at least get a concrete idea of the
 218  * problem by reading your message without the need of looking at the kernel
 219  * code.
 220  *
 221  * Use it for definite and high priority BIOS bugs.
 222  *
 223  * FW_WARN
 224  * Use it for not that clear (e.g. could the kernel messed up things already?)
 225  * and medium priority BIOS bugs.
 226  *
 227  * FW_INFO
 228  * Use this one if you want to tell the user or vendor about something
 229  * suspicious, but generally harmless related to the firmware.
 230  *
 231  * Use it for information or very low priority BIOS bugs.
 232  */
 233 #define FW_BUG          "[Firmware Bug]: "
 234 #define FW_WARN         "[Firmware Warn]: "
 235 #define FW_INFO         "[Firmware Info]: "
 236
 237 #ifdef CONFIG_PRINTK
 238 asmlinkage int vprintk(const char *fmt, va_list args)
 239         __attribute__ ((format (printf, 1, 0)));
 240 asmlinkage int printk(const char * fmt, ...)
 241         __attribute__ ((format (printf, 1, 2))) __cold;
 242
 243 extern int __printk_ratelimit(const char *func);
 244 #define printk_ratelimit() __printk_ratelimit(__func__)
 245 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 246                                    unsigned int interval_msec);
 247
 248 /*
 249  * Print a one-time message (analogous to WARN_ONCE() et al):
 250  */
 251 #define printk_once(x...) ({                    \
 252         static int __print_once = 1;            \
 253                                                 \
 254         if (__print_once) {                     \
 255                 __print_once = 0;               \
 256                 printk(x);                      \
 257         }                                       \
 258 })
 259
 260 void log_buf_kexec_setup(void);
 261 #else
 262 static inline int vprintk(const char *s, va_list args)
 263         __attribute__ ((format (printf, 1, 0)));
 264 static inline int vprintk(const char *s, va_list args) { return 0; }
 265 static inline int printk(const char *s, ...)
 266         __attribute__ ((format (printf, 1, 2)));
 267 static inline int __cold printk(const char *s, ...) { return 0; }
 268 static inline int printk_ratelimit(void) { return 0; }
 269 static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
 270                                           unsigned int interval_msec)   \
 271                 { return false; }
 272
 273 /* No effect, but we still get type checking even in the !PRINTK case: */
 274 #define printk_once(x...) printk(x)
 275
 276 static inline void log_buf_kexec_setup(void)
 277 {
 278 }
 279 #endif
 280
 281 extern int printk_needs_cpu(int cpu);
 282 extern void printk_tick(void);
 283
 284 extern void asmlinkage __attribute__((format(printf, 1, 2)))
 285         early_printk(const char *fmt, ...);
 286
 287 unsigned long int_sqrt(unsigned long);
 288
 289 static inline void console_silent(void)
 290 {
 291         console_loglevel = 0;
 292 }
 293
 294 static inline void console_verbose(void)
 295 {
 296         if (console_loglevel)
 297                 console_loglevel = 15;
 298 }
 299
 300 extern void bust_spinlocks(int yes);
 301 extern void wake_up_klogd(void);
 302 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 303 extern int panic_timeout;
 304 extern int panic_on_oops;
 305 extern int panic_on_unrecovered_nmi;
 306 extern int panic_on_io_nmi;
 307 extern const char *print_tainted(void);
 308 extern void add_taint(unsigned flag);
 309 extern int test_taint(unsigned flag);
 310 extern unsigned long get_taint(void);
 311 extern int root_mountflags;
 312
 313 /* Values used for system_state */
 314 extern enum system_states {
 315         SYSTEM_BOOTING,
 316         SYSTEM_RUNNING,
 317         SYSTEM_HALT,
 318         SYSTEM_POWER_OFF,
 319         SYSTEM_RESTART,
 320         SYSTEM_SUSPEND_DISK,
 321 } system_state;
 322
 323 #define TAINT_PROPRIETARY_MODULE        0
 324 #define TAINT_FORCED_MODULE             1
 325 #define TAINT_UNSAFE_SMP                2
 326 #define TAINT_FORCED_RMMOD              3
 327 #define TAINT_MACHINE_CHECK             4
 328 #define TAINT_BAD_PAGE                  5
 329 #define TAINT_USER                      6
 330 #define TAINT_DIE                       7
 331 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
 332 #define TAINT_WARN                      9
 333 #define TAINT_CRAP                      10
 334
 335 extern void dump_stack(void) __cold;
 336
 337 enum {
 338         DUMP_PREFIX_NONE,
 339         DUMP_PREFIX_ADDRESS,
 340         DUMP_PREFIX_OFFSET
 341 };
 342 extern void hex_dump_to_buffer(const void *buf, size_t len,
 343                                 int rowsize, int groupsize,
 344                                 char *linebuf, size_t linebuflen, bool ascii);
 345 extern void print_hex_dump(const char *level, const char *prefix_str,
 346                                 int prefix_type, int rowsize, int groupsize,
 347                                 const void *buf, size_t len, bool ascii);
 348 extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
 349                         const void *buf, size_t len);
 350
 351 extern const char hex_asc[];
 352 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 353 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 354
 355 static inline char *pack_hex_byte(char *buf, u8 byte)
 356 {
 357         *buf++ = hex_asc_hi(byte);
 358         *buf++ = hex_asc_lo(byte);
 359         return buf;
 360 }
 361
 362 #ifndef pr_fmt
 363 #define pr_fmt(fmt) fmt
 364 #endif
 365
 366 #define pr_emerg(fmt, ...) \
 367         printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
 368 #define pr_alert(fmt, ...) \
 369         printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
 370 #define pr_crit(fmt, ...) \
 371         printk(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
 372 #define pr_err(fmt, ...) \
 373         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
 374 #define pr_warning(fmt, ...) \
 375         printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
 376 #define pr_notice(fmt, ...) \
 377         printk(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
 378 #define pr_info(fmt, ...) \
 379         printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
 380 #define pr_cont(fmt, ...) \
 381         printk(KERN_CONT fmt, ##__VA_ARGS__)
 382
 383 /* pr_devel() should produce zero code unless DEBUG is defined */
 384 #ifdef DEBUG
 385 #define pr_devel(fmt, ...) \
 386         printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
 387 #else
 388 #define pr_devel(fmt, ...) \
 389         ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 390 #endif
 391
 392 /* If you are writing a driver, please use dev_dbg instead */
 393 #if defined(DEBUG)
 394 #define pr_debug(fmt, ...) \
 395         printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
 396 #elif defined(CONFIG_DYNAMIC_DEBUG)
 397 /* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
 398 #define pr_debug(fmt, ...) do { \
 399         dynamic_pr_debug(fmt, ##__VA_ARGS__); \
 400         } while (0)
 401 #else
 402 #define pr_debug(fmt, ...) \
 403         ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 404 #endif
 405
 406 /*
 407  * General tracing related utility functions - trace_printk(),
 408  * tracing_on/tracing_off and tracing_start()/tracing_stop
 409  *
 410  * Use tracing_on/tracing_off when you want to quickly turn on or off
 411  * tracing. It simply enables or disables the recording of the trace events.
 412  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 413  * file, which gives a means for the kernel and userspace to interact.
 414  * Place a tracing_off() in the kernel where you want tracing to end.
 415  * From user space, examine the trace, and then echo 1 > tracing_on
 416  * to continue tracing.
 417  *
 418  * tracing_stop/tracing_start has slightly more overhead. It is used
 419  * by things like suspend to ram where disabling the recording of the
 420  * trace is not enough, but tracing must actually stop because things
 421  * like calling smp_processor_id() may crash the system.
 422  *
 423  * Most likely, you want to use tracing_on/tracing_off.
 424  */
 425 #ifdef CONFIG_RING_BUFFER
 426 void tracing_on(void);
 427 void tracing_off(void);
 428 /* trace_off_permanent stops recording with no way to bring it back */
 429 void tracing_off_permanent(void);
 430 int tracing_is_on(void);
 431 #else
 432 static inline void tracing_on(void) { }
 433 static inline void tracing_off(void) { }
 434 static inline void tracing_off_permanent(void) { }
 435 static inline int tracing_is_on(void) { return 0; }
 436 #endif
 437 #ifdef CONFIG_TRACING
 438 extern void tracing_start(void);
 439 extern void tracing_stop(void);
 440 extern void ftrace_off_permanent(void);
 441
 442 extern void
 443 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
 444
 445 static inline void __attribute__ ((format (printf, 1, 2)))
 446 ____trace_printk_check_format(const char *fmt, ...)
 447 {
 448 }
 449 #define __trace_printk_check_format(fmt, args...)                       \
 450 do {                                                                    \
 451         if (0)                                                          \
 452                 ____trace_printk_check_format(fmt, ##args);             \
 453 } while (0)
 454
 455 /**
 456  * trace_printk - printf formatting in the ftrace buffer
 457  * @fmt: the printf format for printing
 458  *
 459  * Note: __trace_printk is an internal function for trace_printk and
 460  *       the @ip is passed in via the trace_printk macro.
 461  *
 462  * This function allows a kernel developer to debug fast path sections
 463  * that printk is not appropriate for. By scattering in various
 464  * printk like tracing in the code, a developer can quickly see
 465  * where problems are occurring.
 466  *
 467  * This is intended as a debugging tool for the developer only.
 468  * Please refrain from leaving trace_printks scattered around in
 469  * your code.
 470  */
 471
 472 #define trace_printk(fmt, args...)                                      \
 473 do {                                                                    \
 474         __trace_printk_check_format(fmt, ##args);                       \
 475         if (__builtin_constant_p(fmt)) {                                \
 476                 static const char *trace_printk_fmt                     \
 477                   __attribute__((section("__trace_printk_fmt"))) =      \
 478                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 479                                                                         \
 480                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 481         } else                                                          \
 482                 __trace_printk(_THIS_IP_, fmt, ##args);         \
 483 } while (0)
 484
 485 extern int
 486 __trace_bprintk(unsigned long ip, const char *fmt, ...)
 487         __attribute__ ((format (printf, 2, 3)));
 488
 489 extern int
 490 __trace_printk(unsigned long ip, const char *fmt, ...)
 491         __attribute__ ((format (printf, 2, 3)));
 492
 493 /*
 494  * The double __builtin_constant_p is because gcc will give us an error
 495  * if we try to allocate the static variable to fmt if it is not a
 496  * constant. Even with the outer if statement.
 497  */
 498 #define ftrace_vprintk(fmt, vargs)                                      \
 499 do {                                                                    \
 500         if (__builtin_constant_p(fmt)) {                                \
 501                 static const char *trace_printk_fmt                     \
 502                   __attribute__((section("__trace_printk_fmt"))) =      \
 503                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 504                                                                         \
 505                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 506         } else                                                          \
 507                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 508 } while (0)
 509
 510 extern int
 511 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 512
 513 extern int
 514 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 515
 516 extern void ftrace_dump(void);
 517 #else
 518 static inline void
 519 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
 520 static inline int
 521 trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 522
 523 static inline void tracing_start(void) { }
 524 static inline void tracing_stop(void) { }
 525 static inline void ftrace_off_permanent(void) { }
 526 static inline int
 527 trace_printk(const char *fmt, ...)
 528 {
 529         return 0;
 530 }
 531 static inline int
 532 ftrace_vprintk(const char *fmt, va_list ap)
 533 {
 534         return 0;
 535 }
 536 static inline void ftrace_dump(void) { }
 537 #endif /* CONFIG_TRACING */
 538
 539 /*
 540  *      Display an IP address in readable format.
 541  */
 542
 543 #define NIPQUAD(addr) \
 544         ((unsigned char *)&addr)[0], \
 545         ((unsigned char *)&addr)[1], \
 546         ((unsigned char *)&addr)[2], \
 547         ((unsigned char *)&addr)[3]
 548 #define NIPQUAD_FMT "%u.%u.%u.%u"
 549
 550 /*
 551  * min()/max()/clamp() macros that also do
 552  * strict type-checking.. See the
 553  * "unnecessary" pointer comparison.
 554  */
 555 #define min(x, y) ({                            \
 556         typeof(x) _min1 = (x);                  \
 557         typeof(y) _min2 = (y);                  \
 558         (void) (&_min1 == &_min2);              \
 559         _min1 < _min2 ? _min1 : _min2; })
 560
 561 #define max(x, y) ({                            \
 562         typeof(x) _max1 = (x);                  \
 563         typeof(y) _max2 = (y);                  \
 564         (void) (&_max1 == &_max2);              \
 565         _max1 > _max2 ? _max1 : _max2; })
 566
 567 /**
 568  * clamp - return a value clamped to a given range with strict typechecking
 569  * @val: current value
 570  * @min: minimum allowable value
 571  * @max: maximum allowable value
 572  *
 573  * This macro does strict typechecking of min/max to make sure they are of the
 574  * same type as val.  See the unnecessary pointer comparisons.
 575  */
 576 #define clamp(val, min, max) ({                 \
 577         typeof(val) __val = (val);              \
 578         typeof(min) __min = (min);              \
 579         typeof(max) __max = (max);              \
 580         (void) (&__val == &__min);              \
 581         (void) (&__val == &__max);              \
 582         __val = __val < __min ? __min: __val;   \
 583         __val > __max ? __max: __val; })
 584
 585 /*
 586  * ..and if you can't take the strict
 587  * types, you can specify one yourself.
 588  *
 589  * Or not use min/max/clamp at all, of course.
 590  */
 591 #define min_t(type, x, y) ({                    \
 592         type __min1 = (x);                      \
 593         type __min2 = (y);                      \
 594         __min1 < __min2 ? __min1: __min2; })
 595
 596 #define max_t(type, x, y) ({                    \
 597         type __max1 = (x);                      \
 598         type __max2 = (y);                      \
 599         __max1 > __max2 ? __max1: __max2; })
 600
 601 /**
 602  * clamp_t - return a value clamped to a given range using a given type
 603  * @type: the type of variable to use
 604  * @val: current value
 605  * @min: minimum allowable value
 606  * @max: maximum allowable value
 607  *
 608  * This macro does no typechecking and uses temporary variables of type
 609  * 'type' to make all the comparisons.
 610  */
 611 #define clamp_t(type, val, min, max) ({         \
 612         type __val = (val);                     \
 613         type __min = (min);                     \
 614         type __max = (max);                     \
 615         __val = __val < __min ? __min: __val;   \
 616         __val > __max ? __max: __val; })
 617
 618 /**
 619  * clamp_val - return a value clamped to a given range using val's type
 620  * @val: current value
 621  * @min: minimum allowable value
 622  * @max: maximum allowable value
 623  *
 624  * This macro does no typechecking and uses temporary variables of whatever
 625  * type the input argument 'val' is.  This is useful when val is an unsigned
 626  * type and min and max are literals that will otherwise be assigned a signed
 627  * integer type.
 628  */
 629 #define clamp_val(val, min, max) ({             \
 630         typeof(val) __val = (val);              \
 631         typeof(val) __min = (min);              \
 632         typeof(val) __max = (max);              \
 633         __val = __val < __min ? __min: __val;   \
 634         __val > __max ? __max: __val; })
 635
 636
 637 /*
 638  * swap - swap value of @a and @b
 639  */
 640 #define swap(a, b) \
 641         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 642
 643 /**
 644  * container_of - cast a member of a structure out to the containing structure
 645  * @ptr:        the pointer to the member.
 646  * @type:       the type of the container struct this is embedded in.
 647  * @member:     the name of the member within the struct.
 648  *
 649  */
 650 #define container_of(ptr, type, member) ({                      \
 651         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 652         (type *)( (char *)__mptr - offsetof(type,member) );})
 653
 654 struct sysinfo;
 655 extern int do_sysinfo(struct sysinfo *info);
 656
 657 #endif /* __KERNEL__ */
 658
 659 #define SI_LOAD_SHIFT   16
 660 struct sysinfo {
 661         long uptime;                    /* Seconds since boot */
 662         unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
 663         unsigned long totalram;         /* Total usable main memory size */
 664         unsigned long freeram;          /* Available memory size */
 665         unsigned long sharedram;        /* Amount of shared memory */
 666         unsigned long bufferram;        /* Memory used by buffers */
 667         unsigned long totalswap;        /* Total swap space size */
 668         unsigned long freeswap;         /* swap space still available */
 669         unsigned short procs;           /* Number of current processes */
 670         unsigned short pad;             /* explicit padding for m68k */
 671         unsigned long totalhigh;        /* Total high memory size */
 672         unsigned long freehigh;         /* Available high memory size */
 673         unsigned int mem_unit;          /* Memory unit size in bytes */
 674         char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
 675 };
 676
 677 /* Force a compilation error if condition is true */
 678 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 679
 680 /* Force a compilation error if condition is true, but also produce a
 681    result (of value 0 and type size_t), so the expression can be used
 682    e.g. in a structure initializer (or where-ever else comma expressions
 683    aren't permitted). */
 684 #define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1)
 685
 686 /* Trap pasters of __FUNCTION__ at compile-time */
 687 #define __FUNCTION__ (__func__)
 688
 689 /* This helps us to avoid #ifdef CONFIG_NUMA */
 690 #ifdef CONFIG_NUMA
 691 #define NUMA_BUILD 1
 692 #else
 693 #define NUMA_BUILD 0
 694 #endif
 695
 696 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 697 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 698 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 699 #endif
 700
 701 #endif