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/ratelimit.h>
  19 #include <linux/dynamic_printk.h>
  20 #include <asm/byteorder.h>
  21 #include <asm/bug.h>
  22
  23 extern const char linux_banner[];
  24 extern const char linux_proc_banner[];
  25
  26 #define USHORT_MAX      ((u16)(~0U))
  27 #define SHORT_MAX       ((s16)(USHORT_MAX>>1))
  28 #define SHORT_MIN       (-SHORT_MAX - 1)
  29 #define INT_MAX         ((int)(~0U>>1))
  30 #define INT_MIN         (-INT_MAX - 1)
  31 #define UINT_MAX        (~0U)
  32 #define LONG_MAX        ((long)(~0UL>>1))
  33 #define LONG_MIN        (-LONG_MAX - 1)
  34 #define ULONG_MAX       (~0UL)
  35 #define LLONG_MAX       ((long long)(~0ULL>>1))
  36 #define LLONG_MIN       (-LLONG_MAX - 1)
  37 #define ULLONG_MAX      (~0ULL)
  38
  39 #define STACK_MAGIC     0xdeadbeef
  40
  41 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1)
  42 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
  43 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  44 #define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  45
  46 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  47
  48 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  49 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  50 #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
  51 #define DIV_ROUND_CLOSEST(x, divisor)(                  \
  52 {                                                       \
  53         typeof(divisor) __divisor = divisor;            \
  54         (((x) + ((__divisor) / 2)) / (__divisor));      \
  55 }                                                       \
  56 )
  57
  58 #define _RET_IP_                (unsigned long)__builtin_return_address(0)
  59 #define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
  60
  61 #ifdef CONFIG_LBD
  62 # include <asm/div64.h>
  63 # define sector_div(a, b) do_div(a, b)
  64 #else
  65 # define sector_div(n, b)( \
  66 { \
  67         int _res; \
  68         _res = (n) % (b); \
  69         (n) /= (b); \
  70         _res; \
  71 } \
  72 )
  73 #endif
  74
  75 /**
  76  * upper_32_bits - return bits 32-63 of a number
  77  * @n: the number we're accessing
  78  *
  79  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
  80  * the "right shift count >= width of type" warning when that quantity is
  81  * 32-bits.
  82  */
  83 #define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
  84
  85 /**
  86  * lower_32_bits - return bits 0-31 of a number
  87  * @n: the number we're accessing
  88  */
  89 #define lower_32_bits(n) ((u32)(n))
  90
  91 #define KERN_EMERG      "<0>"   /* system is unusable                   */
  92 #define KERN_ALERT      "<1>"   /* action must be taken immediately     */
  93 #define KERN_CRIT       "<2>"   /* critical conditions                  */
  94 #define KERN_ERR        "<3>"   /* error conditions                     */
  95 #define KERN_WARNING    "<4>"   /* warning conditions                   */
  96 #define KERN_NOTICE     "<5>"   /* normal but significant condition     */
  97 #define KERN_INFO       "<6>"   /* informational                        */
  98 #define KERN_DEBUG      "<7>"   /* debug-level messages                 */
  99
 100 /*
 101  * Annotation for a "continued" line of log printout (only done after a
 102  * line that had no enclosing \n). Only to be used by core/arch code
 103  * during early bootup (a continued line is not SMP-safe otherwise).
 104  */
 105 #define KERN_CONT       ""
 106
 107 extern int console_printk[];
 108
 109 #define console_loglevel (console_printk[0])
 110 #define default_message_loglevel (console_printk[1])
 111 #define minimum_console_loglevel (console_printk[2])
 112 #define default_console_loglevel (console_printk[3])
 113
 114 struct completion;
 115 struct pt_regs;
 116 struct user;
 117
 118 #ifdef CONFIG_PREEMPT_VOLUNTARY
 119 extern int _cond_resched(void);
 120 # define might_resched() _cond_resched()
 121 #else
 122 # define might_resched() do { } while (0)
 123 #endif
 124
 125 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 126   void __might_sleep(char *file, int line);
 127 /**
 128  * might_sleep - annotation for functions that can sleep
 129  *
 130  * this macro will print a stack trace if it is executed in an atomic
 131  * context (spinlock, irq-handler, ...).
 132  *
 133  * This is a useful debugging help to be able to catch problems early and not
 134  * be bitten later when the calling function happens to sleep when it is not
 135  * supposed to.
 136  */
 137 # define might_sleep() \
 138         do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)
 139 #else
 140 # define might_sleep() do { might_resched(); } while (0)
 141 #endif
 142
 143 #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 144
 145 #define abs(x) ({                               \
 146                 int __x = (x);                  \
 147                 (__x < 0) ? -__x : __x;         \
 148         })
 149
 150 #ifdef CONFIG_PROVE_LOCKING
 151 void might_fault(void);
 152 #else
 153 static inline void might_fault(void)
 154 {
 155         might_sleep();
 156 }
 157 #endif
 158
 159 extern struct atomic_notifier_head panic_notifier_list;
 160 extern long (*panic_blink)(long time);
 161 NORET_TYPE void panic(const char * fmt, ...)
 162         __attribute__ ((NORET_AND format (printf, 1, 2))) __cold;
 163 extern void oops_enter(void);
 164 extern void oops_exit(void);
 165 extern int oops_may_print(void);
 166 NORET_TYPE void do_exit(long error_code)
 167         ATTRIB_NORET;
 168 NORET_TYPE void complete_and_exit(struct completion *, long)
 169         ATTRIB_NORET;
 170 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 171 extern long simple_strtol(const char *,char **,unsigned int);
 172 extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 173 extern long long simple_strtoll(const char *,char **,unsigned int);
 174 extern int strict_strtoul(const char *, unsigned int, unsigned long *);
 175 extern int strict_strtol(const char *, unsigned int, long *);
 176 extern int strict_strtoull(const char *, unsigned int, unsigned long long *);
 177 extern int strict_strtoll(const char *, unsigned int, long long *);
 178 extern int sprintf(char * buf, const char * fmt, ...)
 179         __attribute__ ((format (printf, 2, 3)));
 180 extern int vsprintf(char *buf, const char *, va_list)
 181         __attribute__ ((format (printf, 2, 0)));
 182 extern int snprintf(char * buf, size_t size, const char * fmt, ...)
 183         __attribute__ ((format (printf, 3, 4)));
 184 extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 185         __attribute__ ((format (printf, 3, 0)));
 186 extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
 187         __attribute__ ((format (printf, 3, 4)));
 188 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 189         __attribute__ ((format (printf, 3, 0)));
 190 extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
 191         __attribute__ ((format (printf, 2, 3)));
 192 extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 193
 194 extern int sscanf(const char *, const char *, ...)
 195         __attribute__ ((format (scanf, 2, 3)));
 196 extern int vsscanf(const char *, const char *, va_list)
 197         __attribute__ ((format (scanf, 2, 0)));
 198
 199 extern int get_option(char **str, int *pint);
 200 extern char *get_options(const char *str, int nints, int *ints);
 201 extern unsigned long long memparse(const char *ptr, char **retptr);
 202
 203 extern int core_kernel_text(unsigned long addr);
 204 extern int __kernel_text_address(unsigned long addr);
 205 extern int kernel_text_address(unsigned long addr);
 206 extern int func_ptr_is_kernel_text(void *ptr);
 207
 208 struct pid;
 209 extern struct pid *session_of_pgrp(struct pid *pgrp);
 210
 211 /*
 212  * FW_BUG
 213  * Add this to a message where you are sure the firmware is buggy or behaves
 214  * really stupid or out of spec. Be aware that the responsible BIOS developer
 215  * should be able to fix this issue or at least get a concrete idea of the
 216  * problem by reading your message without the need of looking at the kernel
 217  * code.
 218  *
 219  * Use it for definite and high priority BIOS bugs.
 220  *
 221  * FW_WARN
 222  * Use it for not that clear (e.g. could the kernel messed up things already?)
 223  * and medium priority BIOS bugs.
 224  *
 225  * FW_INFO
 226  * Use this one if you want to tell the user or vendor about something
 227  * suspicious, but generally harmless related to the firmware.
 228  *
 229  * Use it for information or very low priority BIOS bugs.
 230  */
 231 #define FW_BUG          "[Firmware Bug]: "
 232 #define FW_WARN         "[Firmware Warn]: "
 233 #define FW_INFO         "[Firmware Info]: "
 234
 235 #ifdef CONFIG_PRINTK
 236 asmlinkage int vprintk(const char *fmt, va_list args)
 237         __attribute__ ((format (printf, 1, 0)));
 238 asmlinkage int printk(const char * fmt, ...)
 239         __attribute__ ((format (printf, 1, 2))) __cold;
 240
 241 extern struct ratelimit_state printk_ratelimit_state;
 242 extern int printk_ratelimit(void);
 243 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 244                                    unsigned int interval_msec);
 245
 246 /*
 247  * Print a one-time message (analogous to WARN_ONCE() et al):
 248  */
 249 #define printk_once(x...) ({                    \
 250         static int __print_once = 1;            \
 251                                                 \
 252         if (__print_once) {                     \
 253                 __print_once = 0;               \
 254                 printk(x);                      \
 255         }                                       \
 256 })
 257
 258 #else
 259 static inline int vprintk(const char *s, va_list args)
 260         __attribute__ ((format (printf, 1, 0)));
 261 static inline int vprintk(const char *s, va_list args) { return 0; }
 262 static inline int printk(const char *s, ...)
 263         __attribute__ ((format (printf, 1, 2)));
 264 static inline int __cold printk(const char *s, ...) { return 0; }
 265 static inline int printk_ratelimit(void) { return 0; }
 266 static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
 267                                           unsigned int interval_msec)   \
 268                 { return false; }
 269
 270 /* No effect, but we still get type checking even in the !PRINTK case: */
 271 #define printk_once(x...) printk(x)
 272
 273 #endif
 274
 275 extern int printk_needs_cpu(int cpu);
 276 extern void printk_tick(void);
 277
 278 extern void asmlinkage __attribute__((format(printf, 1, 2)))
 279         early_printk(const char *fmt, ...);
 280
 281 unsigned long int_sqrt(unsigned long);
 282
 283 static inline void console_silent(void)
 284 {
 285         console_loglevel = 0;
 286 }
 287
 288 static inline void console_verbose(void)
 289 {
 290         if (console_loglevel)
 291                 console_loglevel = 15;
 292 }
 293
 294 extern void bust_spinlocks(int yes);
 295 extern void wake_up_klogd(void);
 296 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 297 extern int panic_timeout;
 298 extern int panic_on_oops;
 299 extern int panic_on_unrecovered_nmi;
 300 extern const char *print_tainted(void);
 301 extern void add_taint(unsigned flag);
 302 extern int test_taint(unsigned flag);
 303 extern unsigned long get_taint(void);
 304 extern int root_mountflags;
 305
 306 /* Values used for system_state */
 307 extern enum system_states {
 308         SYSTEM_BOOTING,
 309         SYSTEM_RUNNING,
 310         SYSTEM_HALT,
 311         SYSTEM_POWER_OFF,
 312         SYSTEM_RESTART,
 313         SYSTEM_SUSPEND_DISK,
 314 } system_state;
 315
 316 #define TAINT_PROPRIETARY_MODULE        0
 317 #define TAINT_FORCED_MODULE             1
 318 #define TAINT_UNSAFE_SMP                2
 319 #define TAINT_FORCED_RMMOD              3
 320 #define TAINT_MACHINE_CHECK             4
 321 #define TAINT_BAD_PAGE                  5
 322 #define TAINT_USER                      6
 323 #define TAINT_DIE                       7
 324 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
 325 #define TAINT_WARN                      9
 326 #define TAINT_CRAP                      10
 327
 328 extern void dump_stack(void) __cold;
 329
 330 enum {
 331         DUMP_PREFIX_NONE,
 332         DUMP_PREFIX_ADDRESS,
 333         DUMP_PREFIX_OFFSET
 334 };
 335 extern void hex_dump_to_buffer(const void *buf, size_t len,
 336                                 int rowsize, int groupsize,
 337                                 char *linebuf, size_t linebuflen, bool ascii);
 338 extern void print_hex_dump(const char *level, const char *prefix_str,
 339                                 int prefix_type, int rowsize, int groupsize,
 340                                 const void *buf, size_t len, bool ascii);
 341 extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
 342                         const void *buf, size_t len);
 343
 344 extern const char hex_asc[];
 345 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 346 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 347
 348 static inline char *pack_hex_byte(char *buf, u8 byte)
 349 {
 350         *buf++ = hex_asc_hi(byte);
 351         *buf++ = hex_asc_lo(byte);
 352         return buf;
 353 }
 354
 355 #ifndef pr_fmt
 356 #define pr_fmt(fmt) fmt
 357 #endif
 358
 359 #define pr_emerg(fmt, ...) \
 360         printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
 361 #define pr_alert(fmt, ...) \
 362         printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
 363 #define pr_crit(fmt, ...) \
 364         printk(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
 365 #define pr_err(fmt, ...) \
 366         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
 367 #define pr_warning(fmt, ...) \
 368         printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
 369 #define pr_notice(fmt, ...) \
 370         printk(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
 371 #define pr_info(fmt, ...) \
 372         printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
 373
 374 /* If you are writing a driver, please use dev_dbg instead */
 375 #if defined(DEBUG)
 376 #define pr_debug(fmt, ...) \
 377         printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
 378 #elif defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
 379 #define pr_debug(fmt, ...) do { \
 380         dynamic_pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
 381         } while (0)
 382 #else
 383 #define pr_debug(fmt, ...) \
 384         ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 385 #endif
 386
 387 /*
 388  * General tracing related utility functions - trace_printk(),
 389  * tracing_on/tracing_off and tracing_start()/tracing_stop
 390  *
 391  * Use tracing_on/tracing_off when you want to quickly turn on or off
 392  * tracing. It simply enables or disables the recording of the trace events.
 393  * This also corresponds to the user space debugfs/tracing/tracing_on
 394  * file, which gives a means for the kernel and userspace to interact.
 395  * Place a tracing_off() in the kernel where you want tracing to end.
 396  * From user space, examine the trace, and then echo 1 > tracing_on
 397  * to continue tracing.
 398  *
 399  * tracing_stop/tracing_start has slightly more overhead. It is used
 400  * by things like suspend to ram where disabling the recording of the
 401  * trace is not enough, but tracing must actually stop because things
 402  * like calling smp_processor_id() may crash the system.
 403  *
 404  * Most likely, you want to use tracing_on/tracing_off.
 405  */
 406 #ifdef CONFIG_RING_BUFFER
 407 void tracing_on(void);
 408 void tracing_off(void);
 409 /* trace_off_permanent stops recording with no way to bring it back */
 410 void tracing_off_permanent(void);
 411 int tracing_is_on(void);
 412 #else
 413 static inline void tracing_on(void) { }
 414 static inline void tracing_off(void) { }
 415 static inline void tracing_off_permanent(void) { }
 416 static inline int tracing_is_on(void) { return 0; }
 417 #endif
 418 #ifdef CONFIG_TRACING
 419 extern void tracing_start(void);
 420 extern void tracing_stop(void);
 421 extern void ftrace_off_permanent(void);
 422
 423 extern void
 424 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
 425
 426 static inline void __attribute__ ((format (printf, 1, 2)))
 427 ____trace_printk_check_format(const char *fmt, ...)
 428 {
 429 }
 430 #define __trace_printk_check_format(fmt, args...)                       \
 431 do {                                                                    \
 432         if (0)                                                          \
 433                 ____trace_printk_check_format(fmt, ##args);             \
 434 } while (0)
 435
 436 /**
 437  * trace_printk - printf formatting in the ftrace buffer
 438  * @fmt: the printf format for printing
 439  *
 440  * Note: __trace_printk is an internal function for trace_printk and
 441  *       the @ip is passed in via the trace_printk macro.
 442  *
 443  * This function allows a kernel developer to debug fast path sections
 444  * that printk is not appropriate for. By scattering in various
 445  * printk like tracing in the code, a developer can quickly see
 446  * where problems are occurring.
 447  *
 448  * This is intended as a debugging tool for the developer only.
 449  * Please refrain from leaving trace_printks scattered around in
 450  * your code.
 451  */
 452
 453 #define trace_printk(fmt, args...)                                      \
 454 do {                                                                    \
 455         static const char *trace_printk_fmt                             \
 456         __attribute__((section("__trace_printk_fmt")));                 \
 457                                                                         \
 458         if (!trace_printk_fmt)                                          \
 459                 trace_printk_fmt = fmt;                                 \
 460                                                                         \
 461         __trace_printk_check_format(fmt, ##args);                       \
 462         __trace_printk(_THIS_IP_, trace_printk_fmt, ##args);            \
 463 } while (0)
 464
 465 extern int
 466 __trace_printk(unsigned long ip, const char *fmt, ...)
 467         __attribute__ ((format (printf, 2, 3)));
 468
 469 #define ftrace_vprintk(fmt, vargs)                                      \
 470 do {                                                                    \
 471         static const char *trace_printk_fmt                             \
 472         __attribute__((section("__trace_printk_fmt")));                 \
 473                                                                         \
 474         if (!trace_printk_fmt)                                          \
 475                 trace_printk_fmt = fmt;                                 \
 476                                                                         \
 477         __ftrace_vprintk(_THIS_IP_, trace_printk_fmt, vargs);           \
 478 } while (0)
 479
 480 extern int
 481 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 482
 483 extern void ftrace_dump(void);
 484 #else
 485 static inline void
 486 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
 487 static inline int
 488 trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 489
 490 static inline void tracing_start(void) { }
 491 static inline void tracing_stop(void) { }
 492 static inline void ftrace_off_permanent(void) { }
 493 static inline int
 494 trace_printk(const char *fmt, ...)
 495 {
 496         return 0;
 497 }
 498 static inline int
 499 ftrace_vprintk(const char *fmt, va_list ap)
 500 {
 501         return 0;
 502 }
 503 static inline void ftrace_dump(void) { }
 504 #endif /* CONFIG_TRACING */
 505
 506 /*
 507  *      Display an IP address in readable format.
 508  */
 509
 510 #define NIPQUAD(addr) \
 511         ((unsigned char *)&addr)[0], \
 512         ((unsigned char *)&addr)[1], \
 513         ((unsigned char *)&addr)[2], \
 514         ((unsigned char *)&addr)[3]
 515 #define NIPQUAD_FMT "%u.%u.%u.%u"
 516
 517 #if defined(__LITTLE_ENDIAN)
 518 #define HIPQUAD(addr) \
 519         ((unsigned char *)&addr)[3], \
 520         ((unsigned char *)&addr)[2], \
 521         ((unsigned char *)&addr)[1], \
 522         ((unsigned char *)&addr)[0]
 523 #elif defined(__BIG_ENDIAN)
 524 #define HIPQUAD NIPQUAD
 525 #else
 526 #error "Please fix asm/byteorder.h"
 527 #endif /* __LITTLE_ENDIAN */
 528
 529 /*
 530  * min()/max()/clamp() macros that also do
 531  * strict type-checking.. See the
 532  * "unnecessary" pointer comparison.
 533  */
 534 #define min(x, y) ({                            \
 535         typeof(x) _min1 = (x);                  \
 536         typeof(y) _min2 = (y);                  \
 537         (void) (&_min1 == &_min2);              \
 538         _min1 < _min2 ? _min1 : _min2; })
 539
 540 #define max(x, y) ({                            \
 541         typeof(x) _max1 = (x);                  \
 542         typeof(y) _max2 = (y);                  \
 543         (void) (&_max1 == &_max2);              \
 544         _max1 > _max2 ? _max1 : _max2; })
 545
 546 /**
 547  * clamp - return a value clamped to a given range with strict typechecking
 548  * @val: current value
 549  * @min: minimum allowable value
 550  * @max: maximum allowable value
 551  *
 552  * This macro does strict typechecking of min/max to make sure they are of the
 553  * same type as val.  See the unnecessary pointer comparisons.
 554  */
 555 #define clamp(val, min, max) ({                 \
 556         typeof(val) __val = (val);              \
 557         typeof(min) __min = (min);              \
 558         typeof(max) __max = (max);              \
 559         (void) (&__val == &__min);              \
 560         (void) (&__val == &__max);              \
 561         __val = __val < __min ? __min: __val;   \
 562         __val > __max ? __max: __val; })
 563
 564 /*
 565  * ..and if you can't take the strict
 566  * types, you can specify one yourself.
 567  *
 568  * Or not use min/max/clamp at all, of course.
 569  */
 570 #define min_t(type, x, y) ({                    \
 571         type __min1 = (x);                      \
 572         type __min2 = (y);                      \
 573         __min1 < __min2 ? __min1: __min2; })
 574
 575 #define max_t(type, x, y) ({                    \
 576         type __max1 = (x);                      \
 577         type __max2 = (y);                      \
 578         __max1 > __max2 ? __max1: __max2; })
 579
 580 /**
 581  * clamp_t - return a value clamped to a given range using a given type
 582  * @type: the type of variable to use
 583  * @val: current value
 584  * @min: minimum allowable value
 585  * @max: maximum allowable value
 586  *
 587  * This macro does no typechecking and uses temporary variables of type
 588  * 'type' to make all the comparisons.
 589  */
 590 #define clamp_t(type, val, min, max) ({         \
 591         type __val = (val);                     \
 592         type __min = (min);                     \
 593         type __max = (max);                     \
 594         __val = __val < __min ? __min: __val;   \
 595         __val > __max ? __max: __val; })
 596
 597 /**
 598  * clamp_val - return a value clamped to a given range using val's type
 599  * @val: current value
 600  * @min: minimum allowable value
 601  * @max: maximum allowable value
 602  *
 603  * This macro does no typechecking and uses temporary variables of whatever
 604  * type the input argument 'val' is.  This is useful when val is an unsigned
 605  * type and min and max are literals that will otherwise be assigned a signed
 606  * integer type.
 607  */
 608 #define clamp_val(val, min, max) ({             \
 609         typeof(val) __val = (val);              \
 610         typeof(val) __min = (min);              \
 611         typeof(val) __max = (max);              \
 612         __val = __val < __min ? __min: __val;   \
 613         __val > __max ? __max: __val; })
 614
 615
 616 /*
 617  * swap - swap value of @a and @b
 618  */
 619 #define swap(a, b) \
 620         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 621
 622 /**
 623  * container_of - cast a member of a structure out to the containing structure
 624  * @ptr:        the pointer to the member.
 625  * @type:       the type of the container struct this is embedded in.
 626  * @member:     the name of the member within the struct.
 627  *
 628  */
 629 #define container_of(ptr, type, member) ({                      \
 630         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 631         (type *)( (char *)__mptr - offsetof(type,member) );})
 632
 633 struct sysinfo;
 634 extern int do_sysinfo(struct sysinfo *info);
 635
 636 #endif /* __KERNEL__ */
 637
 638 #define SI_LOAD_SHIFT   16
 639 struct sysinfo {
 640         long uptime;                    /* Seconds since boot */
 641         unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
 642         unsigned long totalram;         /* Total usable main memory size */
 643         unsigned long freeram;          /* Available memory size */
 644         unsigned long sharedram;        /* Amount of shared memory */
 645         unsigned long bufferram;        /* Memory used by buffers */
 646         unsigned long totalswap;        /* Total swap space size */
 647         unsigned long freeswap;         /* swap space still available */
 648         unsigned short procs;           /* Number of current processes */
 649         unsigned short pad;             /* explicit padding for m68k */
 650         unsigned long totalhigh;        /* Total high memory size */
 651         unsigned long freehigh;         /* Available high memory size */
 652         unsigned int mem_unit;          /* Memory unit size in bytes */
 653         char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
 654 };
 655
 656 /* Force a compilation error if condition is true */
 657 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 658
 659 /* Force a compilation error if condition is true, but also produce a
 660    result (of value 0 and type size_t), so the expression can be used
 661    e.g. in a structure initializer (or where-ever else comma expressions
 662    aren't permitted). */
 663 #define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1)
 664
 665 /* Trap pasters of __FUNCTION__ at compile-time */
 666 #define __FUNCTION__ (__func__)
 667
 668 /* This helps us to avoid #ifdef CONFIG_NUMA */
 669 #ifdef CONFIG_NUMA
 670 #define NUMA_BUILD 1
 671 #else
 672 #define NUMA_BUILD 0
 673 #endif
 674
 675 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 676 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 677 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 678 #endif
 679
 680 #endif