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                 long __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 extern int printk_delay_msec;
 249
 250 /*
 251  * Print a one-time message (analogous to WARN_ONCE() et al):
 252  */
 253 #define printk_once(x...) ({                    \
 254         static bool __print_once = true;        \
 255                                                 \
 256         if (__print_once) {                     \
 257                 __print_once = false;           \
 258                 printk(x);                      \
 259         }                                       \
 260 })
 261
 262 void log_buf_kexec_setup(void);
 263 #else
 264 static inline int vprintk(const char *s, va_list args)
 265         __attribute__ ((format (printf, 1, 0)));
 266 static inline int vprintk(const char *s, va_list args) { return 0; }
 267 static inline int printk(const char *s, ...)
 268         __attribute__ ((format (printf, 1, 2)));
 269 static inline int __cold printk(const char *s, ...) { return 0; }
 270 static inline int printk_ratelimit(void) { return 0; }
 271 static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
 272                                           unsigned int interval_msec)   \
 273                 { return false; }
 274
 275 /* No effect, but we still get type checking even in the !PRINTK case: */
 276 #define printk_once(x...) printk(x)
 277
 278 static inline void log_buf_kexec_setup(void)
 279 {
 280 }
 281 #endif
 282
 283 extern int printk_needs_cpu(int cpu);
 284 extern void printk_tick(void);
 285
 286 extern void asmlinkage __attribute__((format(printf, 1, 2)))
 287         early_printk(const char *fmt, ...);
 288
 289 unsigned long int_sqrt(unsigned long);
 290
 291 static inline void console_silent(void)
 292 {
 293         console_loglevel = 0;
 294 }
 295
 296 static inline void console_verbose(void)
 297 {
 298         if (console_loglevel)
 299                 console_loglevel = 15;
 300 }
 301
 302 extern void bust_spinlocks(int yes);
 303 extern void wake_up_klogd(void);
 304 extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 305 extern int panic_timeout;
 306 extern int panic_on_oops;
 307 extern int panic_on_unrecovered_nmi;
 308 extern int panic_on_io_nmi;
 309 extern const char *print_tainted(void);
 310 extern void add_taint(unsigned flag);
 311 extern int test_taint(unsigned flag);
 312 extern unsigned long get_taint(void);
 313 extern int root_mountflags;
 314
 315 /* Values used for system_state */
 316 extern enum system_states {
 317         SYSTEM_BOOTING,
 318         SYSTEM_RUNNING,
 319         SYSTEM_HALT,
 320         SYSTEM_POWER_OFF,
 321         SYSTEM_RESTART,
 322         SYSTEM_SUSPEND_DISK,
 323 } system_state;
 324
 325 #define TAINT_PROPRIETARY_MODULE        0
 326 #define TAINT_FORCED_MODULE             1
 327 #define TAINT_UNSAFE_SMP                2
 328 #define TAINT_FORCED_RMMOD              3
 329 #define TAINT_MACHINE_CHECK             4
 330 #define TAINT_BAD_PAGE                  5
 331 #define TAINT_USER                      6
 332 #define TAINT_DIE                       7
 333 #define TAINT_OVERRIDDEN_ACPI_TABLE     8
 334 #define TAINT_WARN                      9
 335 #define TAINT_CRAP                      10
 336
 337 extern void dump_stack(void) __cold;
 338
 339 enum {
 340         DUMP_PREFIX_NONE,
 341         DUMP_PREFIX_ADDRESS,
 342         DUMP_PREFIX_OFFSET
 343 };
 344 extern void hex_dump_to_buffer(const void *buf, size_t len,
 345                                 int rowsize, int groupsize,
 346                                 char *linebuf, size_t linebuflen, bool ascii);
 347 extern void print_hex_dump(const char *level, const char *prefix_str,
 348                                 int prefix_type, int rowsize, int groupsize,
 349                                 const void *buf, size_t len, bool ascii);
 350 extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
 351                         const void *buf, size_t len);
 352
 353 extern const char hex_asc[];
 354 #define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 355 #define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 356
 357 static inline char *pack_hex_byte(char *buf, u8 byte)
 358 {
 359         *buf++ = hex_asc_hi(byte);
 360         *buf++ = hex_asc_lo(byte);
 361         return buf;
 362 }
 363
 364 #ifndef pr_fmt
 365 #define pr_fmt(fmt) fmt
 366 #endif
 367
 368 #define pr_emerg(fmt, ...) \
 369         printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
 370 #define pr_alert(fmt, ...) \
 371         printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
 372 #define pr_crit(fmt, ...) \
 373         printk(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
 374 #define pr_err(fmt, ...) \
 375         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
 376 #define pr_warning(fmt, ...) \
 377         printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
 378 #define pr_notice(fmt, ...) \
 379         printk(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
 380 #define pr_info(fmt, ...) \
 381         printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
 382 #define pr_cont(fmt, ...) \
 383         printk(KERN_CONT fmt, ##__VA_ARGS__)
 384
 385 /* pr_devel() should produce zero code unless DEBUG is defined */
 386 #ifdef DEBUG
 387 #define pr_devel(fmt, ...) \
 388         printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
 389 #else
 390 #define pr_devel(fmt, ...) \
 391         ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 392 #endif
 393
 394 /* If you are writing a driver, please use dev_dbg instead */
 395 #if defined(DEBUG)
 396 #define pr_debug(fmt, ...) \
 397         printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
 398 #elif defined(CONFIG_DYNAMIC_DEBUG)
 399 /* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
 400 #define pr_debug(fmt, ...) do { \
 401         dynamic_pr_debug(fmt, ##__VA_ARGS__); \
 402         } while (0)
 403 #else
 404 #define pr_debug(fmt, ...) \
 405         ({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
 406 #endif
 407
 408 /*
 409  * General tracing related utility functions - trace_printk(),
 410  * tracing_on/tracing_off and tracing_start()/tracing_stop
 411  *
 412  * Use tracing_on/tracing_off when you want to quickly turn on or off
 413  * tracing. It simply enables or disables the recording of the trace events.
 414  * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 415  * file, which gives a means for the kernel and userspace to interact.
 416  * Place a tracing_off() in the kernel where you want tracing to end.
 417  * From user space, examine the trace, and then echo 1 > tracing_on
 418  * to continue tracing.
 419  *
 420  * tracing_stop/tracing_start has slightly more overhead. It is used
 421  * by things like suspend to ram where disabling the recording of the
 422  * trace is not enough, but tracing must actually stop because things
 423  * like calling smp_processor_id() may crash the system.
 424  *
 425  * Most likely, you want to use tracing_on/tracing_off.
 426  */
 427 #ifdef CONFIG_RING_BUFFER
 428 void tracing_on(void);
 429 void tracing_off(void);
 430 /* trace_off_permanent stops recording with no way to bring it back */
 431 void tracing_off_permanent(void);
 432 int tracing_is_on(void);
 433 #else
 434 static inline void tracing_on(void) { }
 435 static inline void tracing_off(void) { }
 436 static inline void tracing_off_permanent(void) { }
 437 static inline int tracing_is_on(void) { return 0; }
 438 #endif
 439 #ifdef CONFIG_TRACING
 440 extern void tracing_start(void);
 441 extern void tracing_stop(void);
 442 extern void ftrace_off_permanent(void);
 443
 444 extern void
 445 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
 446
 447 static inline void __attribute__ ((format (printf, 1, 2)))
 448 ____trace_printk_check_format(const char *fmt, ...)
 449 {
 450 }
 451 #define __trace_printk_check_format(fmt, args...)                       \
 452 do {                                                                    \
 453         if (0)                                                          \
 454                 ____trace_printk_check_format(fmt, ##args);             \
 455 } while (0)
 456
 457 /**
 458  * trace_printk - printf formatting in the ftrace buffer
 459  * @fmt: the printf format for printing
 460  *
 461  * Note: __trace_printk is an internal function for trace_printk and
 462  *       the @ip is passed in via the trace_printk macro.
 463  *
 464  * This function allows a kernel developer to debug fast path sections
 465  * that printk is not appropriate for. By scattering in various
 466  * printk like tracing in the code, a developer can quickly see
 467  * where problems are occurring.
 468  *
 469  * This is intended as a debugging tool for the developer only.
 470  * Please refrain from leaving trace_printks scattered around in
 471  * your code.
 472  */
 473
 474 #define trace_printk(fmt, args...)                                      \
 475 do {                                                                    \
 476         __trace_printk_check_format(fmt, ##args);                       \
 477         if (__builtin_constant_p(fmt)) {                                \
 478                 static const char *trace_printk_fmt                     \
 479                   __attribute__((section("__trace_printk_fmt"))) =      \
 480                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 481                                                                         \
 482                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 483         } else                                                          \
 484                 __trace_printk(_THIS_IP_, fmt, ##args);         \
 485 } while (0)
 486
 487 extern int
 488 __trace_bprintk(unsigned long ip, const char *fmt, ...)
 489         __attribute__ ((format (printf, 2, 3)));
 490
 491 extern int
 492 __trace_printk(unsigned long ip, const char *fmt, ...)
 493         __attribute__ ((format (printf, 2, 3)));
 494
 495 /*
 496  * The double __builtin_constant_p is because gcc will give us an error
 497  * if we try to allocate the static variable to fmt if it is not a
 498  * constant. Even with the outer if statement.
 499  */
 500 #define ftrace_vprintk(fmt, vargs)                                      \
 501 do {                                                                    \
 502         if (__builtin_constant_p(fmt)) {                                \
 503                 static const char *trace_printk_fmt                     \
 504                   __attribute__((section("__trace_printk_fmt"))) =      \
 505                         __builtin_constant_p(fmt) ? fmt : NULL;         \
 506                                                                         \
 507                 __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 508         } else                                                          \
 509                 __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 510 } while (0)
 511
 512 extern int
 513 __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 514
 515 extern int
 516 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 517
 518 extern void ftrace_dump(void);
 519 #else
 520 static inline void
 521 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
 522 static inline int
 523 trace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 524
 525 static inline void tracing_start(void) { }
 526 static inline void tracing_stop(void) { }
 527 static inline void ftrace_off_permanent(void) { }
 528 static inline int
 529 trace_printk(const char *fmt, ...)
 530 {
 531         return 0;
 532 }
 533 static inline int
 534 ftrace_vprintk(const char *fmt, va_list ap)
 535 {
 536         return 0;
 537 }
 538 static inline void ftrace_dump(void) { }
 539 #endif /* CONFIG_TRACING */
 540
 541 /*
 542  *      Display an IP address in readable format.
 543  */
 544
 545 #define NIPQUAD(addr) \
 546         ((unsigned char *)&addr)[0], \
 547         ((unsigned char *)&addr)[1], \
 548         ((unsigned char *)&addr)[2], \
 549         ((unsigned char *)&addr)[3]
 550 #define NIPQUAD_FMT "%u.%u.%u.%u"
 551
 552 /*
 553  * min()/max()/clamp() macros that also do
 554  * strict type-checking.. See the
 555  * "unnecessary" pointer comparison.
 556  */
 557 #define min(x, y) ({                            \
 558         typeof(x) _min1 = (x);                  \
 559         typeof(y) _min2 = (y);                  \
 560         (void) (&_min1 == &_min2);              \
 561         _min1 < _min2 ? _min1 : _min2; })
 562
 563 #define max(x, y) ({                            \
 564         typeof(x) _max1 = (x);                  \
 565         typeof(y) _max2 = (y);                  \
 566         (void) (&_max1 == &_max2);              \
 567         _max1 > _max2 ? _max1 : _max2; })
 568
 569 /**
 570  * clamp - return a value clamped to a given range with strict typechecking
 571  * @val: current value
 572  * @min: minimum allowable value
 573  * @max: maximum allowable value
 574  *
 575  * This macro does strict typechecking of min/max to make sure they are of the
 576  * same type as val.  See the unnecessary pointer comparisons.
 577  */
 578 #define clamp(val, min, max) ({                 \
 579         typeof(val) __val = (val);              \
 580         typeof(min) __min = (min);              \
 581         typeof(max) __max = (max);              \
 582         (void) (&__val == &__min);              \
 583         (void) (&__val == &__max);              \
 584         __val = __val < __min ? __min: __val;   \
 585         __val > __max ? __max: __val; })
 586
 587 /*
 588  * ..and if you can't take the strict
 589  * types, you can specify one yourself.
 590  *
 591  * Or not use min/max/clamp at all, of course.
 592  */
 593 #define min_t(type, x, y) ({                    \
 594         type __min1 = (x);                      \
 595         type __min2 = (y);                      \
 596         __min1 < __min2 ? __min1: __min2; })
 597
 598 #define max_t(type, x, y) ({                    \
 599         type __max1 = (x);                      \
 600         type __max2 = (y);                      \
 601         __max1 > __max2 ? __max1: __max2; })
 602
 603 /**
 604  * clamp_t - return a value clamped to a given range using a given type
 605  * @type: the type of variable to use
 606  * @val: current value
 607  * @min: minimum allowable value
 608  * @max: maximum allowable value
 609  *
 610  * This macro does no typechecking and uses temporary variables of type
 611  * 'type' to make all the comparisons.
 612  */
 613 #define clamp_t(type, val, min, max) ({         \
 614         type __val = (val);                     \
 615         type __min = (min);                     \
 616         type __max = (max);                     \
 617         __val = __val < __min ? __min: __val;   \
 618         __val > __max ? __max: __val; })
 619
 620 /**
 621  * clamp_val - return a value clamped to a given range using val's type
 622  * @val: current value
 623  * @min: minimum allowable value
 624  * @max: maximum allowable value
 625  *
 626  * This macro does no typechecking and uses temporary variables of whatever
 627  * type the input argument 'val' is.  This is useful when val is an unsigned
 628  * type and min and max are literals that will otherwise be assigned a signed
 629  * integer type.
 630  */
 631 #define clamp_val(val, min, max) ({             \
 632         typeof(val) __val = (val);              \
 633         typeof(val) __min = (min);              \
 634         typeof(val) __max = (max);              \
 635         __val = __val < __min ? __min: __val;   \
 636         __val > __max ? __max: __val; })
 637
 638
 639 /*
 640  * swap - swap value of @a and @b
 641  */
 642 #define swap(a, b) \
 643         do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 644
 645 /**
 646  * container_of - cast a member of a structure out to the containing structure
 647  * @ptr:        the pointer to the member.
 648  * @type:       the type of the container struct this is embedded in.
 649  * @member:     the name of the member within the struct.
 650  *
 651  */
 652 #define container_of(ptr, type, member) ({                      \
 653         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 654         (type *)( (char *)__mptr - offsetof(type,member) );})
 655
 656 struct sysinfo;
 657 extern int do_sysinfo(struct sysinfo *info);
 658
 659 #endif /* __KERNEL__ */
 660
 661 #ifndef __EXPORTED_HEADERS__
 662 #ifndef __KERNEL__
 663 #warning Attempt to use kernel headers from user space, see http://kernelnewbies.org/KernelHeaders
 664 #endif /* __KERNEL__ */
 665 #endif /* __EXPORTED_HEADERS__ */
 666
 667 #define SI_LOAD_SHIFT   16
 668 struct sysinfo {
 669         long uptime;                    /* Seconds since boot */
 670         unsigned long loads[3];         /* 1, 5, and 15 minute load averages */
 671         unsigned long totalram;         /* Total usable main memory size */
 672         unsigned long freeram;          /* Available memory size */
 673         unsigned long sharedram;        /* Amount of shared memory */
 674         unsigned long bufferram;        /* Memory used by buffers */
 675         unsigned long totalswap;        /* Total swap space size */
 676         unsigned long freeswap;         /* swap space still available */
 677         unsigned short procs;           /* Number of current processes */
 678         unsigned short pad;             /* explicit padding for m68k */
 679         unsigned long totalhigh;        /* Total high memory size */
 680         unsigned long freehigh;         /* Available high memory size */
 681         unsigned int mem_unit;          /* Memory unit size in bytes */
 682         char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
 683 };
 684
 685 /* Force a compilation error if condition is true */
 686 #define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
 687
 688 /* Force a compilation error if condition is constant and true */
 689 #define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
 690
 691 /* Force a compilation error if condition is true, but also produce a
 692    result (of value 0 and type size_t), so the expression can be used
 693    e.g. in a structure initializer (or where-ever else comma expressions
 694    aren't permitted). */
 695 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
 696 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 697
 698 /* Trap pasters of __FUNCTION__ at compile-time */
 699 #define __FUNCTION__ (__func__)
 700
 701 /* This helps us to avoid #ifdef CONFIG_NUMA */
 702 #ifdef CONFIG_NUMA
 703 #define NUMA_BUILD 1
 704 #else
 705 #define NUMA_BUILD 0
 706 #endif
 707
 708 /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 709 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 710 # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 711 #endif
 712
 713 #endif