linux/include/linux/kernel.h
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   1#ifndef _LINUX_KERNEL_H
   2#define _LINUX_KERNEL_H
   3
   4
   5#include <stdarg.h>
   6#include <linux/linkage.h>
   7#include <linux/stddef.h>
   8#include <linux/types.h>
   9#include <linux/compiler.h>
  10#include <linux/bitops.h>
  11#include <linux/log2.h>
  12#include <linux/typecheck.h>
  13#include <linux/printk.h>
  14#include <linux/dynamic_debug.h>
  15#include <asm/byteorder.h>
  16#include <uapi/linux/kernel.h>
  17
  18#define USHRT_MAX       ((u16)(~0U))
  19#define SHRT_MAX        ((s16)(USHRT_MAX>>1))
  20#define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
  21#define INT_MAX         ((int)(~0U>>1))
  22#define INT_MIN         (-INT_MAX - 1)
  23#define UINT_MAX        (~0U)
  24#define LONG_MAX        ((long)(~0UL>>1))
  25#define LONG_MIN        (-LONG_MAX - 1)
  26#define ULONG_MAX       (~0UL)
  27#define LLONG_MAX       ((long long)(~0ULL>>1))
  28#define LLONG_MIN       (-LLONG_MAX - 1)
  29#define ULLONG_MAX      (~0ULL)
  30#define SIZE_MAX        (~(size_t)0)
  31
  32#define STACK_MAGIC     0xdeadbeef
  33
  34#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
  35
  36#define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
  37#define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
  38#define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
  39#define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)
  40
  41#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  42
  43/*
  44 * This looks more complex than it should be. But we need to
  45 * get the type for the ~ right in round_down (it needs to be
  46 * as wide as the result!), and we want to evaluate the macro
  47 * arguments just once each.
  48 */
  49#define __round_mask(x, y) ((__typeof__(x))((y)-1))
  50#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
  51#define round_down(x, y) ((x) & ~__round_mask(x, y))
  52
  53#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
  54#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
  55#define DIV_ROUND_UP_ULL(ll,d) \
  56        ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })
  57
  58#if BITS_PER_LONG == 32
  59# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
  60#else
  61# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
  62#endif
  63
  64/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
  65#define roundup(x, y) (                                 \
  66{                                                       \
  67        const typeof(y) __y = y;                        \
  68        (((x) + (__y - 1)) / __y) * __y;                \
  69}                                                       \
  70)
  71#define rounddown(x, y) (                               \
  72{                                                       \
  73        typeof(x) __x = (x);                            \
  74        __x - (__x % (y));                              \
  75}                                                       \
  76)
  77
  78/*
  79 * Divide positive or negative dividend by positive divisor and round
  80 * to closest integer. Result is undefined for negative divisors.
  81 */
  82#define DIV_ROUND_CLOSEST(x, divisor)(                  \
  83{                                                       \
  84        typeof(x) __x = x;                              \
  85        typeof(divisor) __d = divisor;                  \
  86        (((typeof(x))-1) > 0 || (__x) > 0) ?            \
  87                (((__x) + ((__d) / 2)) / (__d)) :       \
  88                (((__x) - ((__d) / 2)) / (__d));        \
  89}                                                       \
  90)
  91
  92/*
  93 * Multiplies an integer by a fraction, while avoiding unnecessary
  94 * overflow or loss of precision.
  95 */
  96#define mult_frac(x, numer, denom)(                     \
  97{                                                       \
  98        typeof(x) quot = (x) / (denom);                 \
  99        typeof(x) rem  = (x) % (denom);                 \
 100        (quot * (numer)) + ((rem * (numer)) / (denom)); \
 101}                                                       \
 102)
 103
 104
 105#define _RET_IP_                (unsigned long)__builtin_return_address(0)
 106#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 107
 108#ifdef CONFIG_LBDAF
 109# include <asm/div64.h>
 110# define sector_div(a, b) do_div(a, b)
 111#else
 112# define sector_div(n, b)( \
 113{ \
 114        int _res; \
 115        _res = (n) % (b); \
 116        (n) /= (b); \
 117        _res; \
 118} \
 119)
 120#endif
 121
 122/**
 123 * upper_32_bits - return bits 32-63 of a number
 124 * @n: the number we're accessing
 125 *
 126 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 127 * the "right shift count >= width of type" warning when that quantity is
 128 * 32-bits.
 129 */
 130#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 131
 132/**
 133 * lower_32_bits - return bits 0-31 of a number
 134 * @n: the number we're accessing
 135 */
 136#define lower_32_bits(n) ((u32)(n))
 137
 138struct completion;
 139struct pt_regs;
 140struct user;
 141
 142#ifdef CONFIG_PREEMPT_VOLUNTARY
 143extern int _cond_resched(void);
 144# define might_resched() _cond_resched()
 145#else
 146# define might_resched() do { } while (0)
 147#endif
 148
 149#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 150  void __might_sleep(const char *file, int line, int preempt_offset);
 151/**
 152 * might_sleep - annotation for functions that can sleep
 153 *
 154 * this macro will print a stack trace if it is executed in an atomic
 155 * context (spinlock, irq-handler, ...).
 156 *
 157 * This is a useful debugging help to be able to catch problems early and not
 158 * be bitten later when the calling function happens to sleep when it is not
 159 * supposed to.
 160 */
 161# define might_sleep() \
 162        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 163#else
 164  static inline void __might_sleep(const char *file, int line,
 165                                   int preempt_offset) { }
 166# define might_sleep() do { might_resched(); } while (0)
 167#endif
 168
 169#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 170
 171/*
 172 * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
 173 * input types abs() returns a signed long.
 174 * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 175 * for those.
 176 */
 177#define abs(x) ({                                               \
 178                long ret;                                       \
 179                if (sizeof(x) == sizeof(long)) {                \
 180                        long __x = (x);                         \
 181                        ret = (__x < 0) ? -__x : __x;           \
 182                } else {                                        \
 183                        int __x = (x);                          \
 184                        ret = (__x < 0) ? -__x : __x;           \
 185                }                                               \
 186                ret;                                            \
 187        })
 188
 189#define abs64(x) ({                             \
 190                s64 __x = (x);                  \
 191                (__x < 0) ? -__x : __x;         \
 192        })
 193
 194#ifdef CONFIG_PROVE_LOCKING
 195void might_fault(void);
 196#else
 197static inline void might_fault(void)
 198{
 199        might_sleep();
 200}
 201#endif
 202
 203extern struct atomic_notifier_head panic_notifier_list;
 204extern long (*panic_blink)(int state);
 205__printf(1, 2)
 206void panic(const char *fmt, ...)
 207        __noreturn __cold;
 208extern void oops_enter(void);
 209extern void oops_exit(void);
 210void print_oops_end_marker(void);
 211extern int oops_may_print(void);
 212void do_exit(long error_code)
 213        __noreturn;
 214void complete_and_exit(struct completion *, long)
 215        __noreturn;
 216
 217/* Internal, do not use. */
 218int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 219int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 220
 221int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 222int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 223static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 224{
 225        /*
 226         * We want to shortcut function call, but
 227         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 228         */
 229        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 230            __alignof__(unsigned long) == __alignof__(unsigned long long))
 231                return kstrtoull(s, base, (unsigned long long *)res);
 232        else
 233                return _kstrtoul(s, base, res);
 234}
 235
 236static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 237{
 238        /*
 239         * We want to shortcut function call, but
 240         * __builtin_types_compatible_p(long, long long) = 0.
 241         */
 242        if (sizeof(long) == sizeof(long long) &&
 243            __alignof__(long) == __alignof__(long long))
 244                return kstrtoll(s, base, (long long *)res);
 245        else
 246                return _kstrtol(s, base, res);
 247}
 248
 249int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 250int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 251
 252static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 253{
 254        return kstrtoull(s, base, res);
 255}
 256
 257static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 258{
 259        return kstrtoll(s, base, res);
 260}
 261
 262static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 263{
 264        return kstrtouint(s, base, res);
 265}
 266
 267static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 268{
 269        return kstrtoint(s, base, res);
 270}
 271
 272int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 273int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 274int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 275int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 276
 277int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 278int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 279int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 280int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 281int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 282int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 283int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 284int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 285int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 286int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 287
 288static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 289{
 290        return kstrtoull_from_user(s, count, base, res);
 291}
 292
 293static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 294{
 295        return kstrtoll_from_user(s, count, base, res);
 296}
 297
 298static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 299{
 300        return kstrtouint_from_user(s, count, base, res);
 301}
 302
 303static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 304{
 305        return kstrtoint_from_user(s, count, base, res);
 306}
 307
 308/* Obsolete, do not use.  Use kstrto<foo> instead */
 309
 310extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 311extern long simple_strtol(const char *,char **,unsigned int);
 312extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 313extern long long simple_strtoll(const char *,char **,unsigned int);
 314#define strict_strtoul  kstrtoul
 315#define strict_strtol   kstrtol
 316#define strict_strtoull kstrtoull
 317#define strict_strtoll  kstrtoll
 318
 319extern int num_to_str(char *buf, int size, unsigned long long num);
 320
 321/* lib/printf utilities */
 322
 323extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 324extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 325extern __printf(3, 4)
 326int snprintf(char *buf, size_t size, const char *fmt, ...);
 327extern __printf(3, 0)
 328int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 329extern __printf(3, 4)
 330int scnprintf(char *buf, size_t size, const char *fmt, ...);
 331extern __printf(3, 0)
 332int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 333extern __printf(2, 3)
 334char *kasprintf(gfp_t gfp, const char *fmt, ...);
 335extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 336
 337extern __scanf(2, 3)
 338int sscanf(const char *, const char *, ...);
 339extern __scanf(2, 0)
 340int vsscanf(const char *, const char *, va_list);
 341
 342extern int get_option(char **str, int *pint);
 343extern char *get_options(const char *str, int nints, int *ints);
 344extern unsigned long long memparse(const char *ptr, char **retptr);
 345
 346extern int core_kernel_text(unsigned long addr);
 347extern int core_kernel_data(unsigned long addr);
 348extern int __kernel_text_address(unsigned long addr);
 349extern int kernel_text_address(unsigned long addr);
 350extern int func_ptr_is_kernel_text(void *ptr);
 351
 352struct pid;
 353extern struct pid *session_of_pgrp(struct pid *pgrp);
 354
 355unsigned long int_sqrt(unsigned long);
 356
 357extern void bust_spinlocks(int yes);
 358extern void wake_up_klogd(void);
 359extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 360extern int panic_timeout;
 361extern int panic_on_oops;
 362extern int panic_on_unrecovered_nmi;
 363extern int panic_on_io_nmi;
 364extern int sysctl_panic_on_stackoverflow;
 365extern const char *print_tainted(void);
 366extern void add_taint(unsigned flag);
 367extern int test_taint(unsigned flag);
 368extern unsigned long get_taint(void);
 369extern int root_mountflags;
 370
 371extern bool early_boot_irqs_disabled;
 372
 373/* Values used for system_state */
 374extern enum system_states {
 375        SYSTEM_BOOTING,
 376        SYSTEM_RUNNING,
 377        SYSTEM_HALT,
 378        SYSTEM_POWER_OFF,
 379        SYSTEM_RESTART,
 380} system_state;
 381
 382#define TAINT_PROPRIETARY_MODULE        0
 383#define TAINT_FORCED_MODULE             1
 384#define TAINT_UNSAFE_SMP                2
 385#define TAINT_FORCED_RMMOD              3
 386#define TAINT_MACHINE_CHECK             4
 387#define TAINT_BAD_PAGE                  5
 388#define TAINT_USER                      6
 389#define TAINT_DIE                       7
 390#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 391#define TAINT_WARN                      9
 392#define TAINT_CRAP                      10
 393#define TAINT_FIRMWARE_WORKAROUND       11
 394#define TAINT_OOT_MODULE                12
 395
 396extern const char hex_asc[];
 397#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 398#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 399
 400static inline char *hex_byte_pack(char *buf, u8 byte)
 401{
 402        *buf++ = hex_asc_hi(byte);
 403        *buf++ = hex_asc_lo(byte);
 404        return buf;
 405}
 406
 407static inline char * __deprecated pack_hex_byte(char *buf, u8 byte)
 408{
 409        return hex_byte_pack(buf, byte);
 410}
 411
 412extern int hex_to_bin(char ch);
 413extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 414
 415/*
 416 * General tracing related utility functions - trace_printk(),
 417 * tracing_on/tracing_off and tracing_start()/tracing_stop
 418 *
 419 * Use tracing_on/tracing_off when you want to quickly turn on or off
 420 * tracing. It simply enables or disables the recording of the trace events.
 421 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 422 * file, which gives a means for the kernel and userspace to interact.
 423 * Place a tracing_off() in the kernel where you want tracing to end.
 424 * From user space, examine the trace, and then echo 1 > tracing_on
 425 * to continue tracing.
 426 *
 427 * tracing_stop/tracing_start has slightly more overhead. It is used
 428 * by things like suspend to ram where disabling the recording of the
 429 * trace is not enough, but tracing must actually stop because things
 430 * like calling smp_processor_id() may crash the system.
 431 *
 432 * Most likely, you want to use tracing_on/tracing_off.
 433 */
 434#ifdef CONFIG_RING_BUFFER
 435/* trace_off_permanent stops recording with no way to bring it back */
 436void tracing_off_permanent(void);
 437#else
 438static inline void tracing_off_permanent(void) { }
 439#endif
 440
 441enum ftrace_dump_mode {
 442        DUMP_NONE,
 443        DUMP_ALL,
 444        DUMP_ORIG,
 445};
 446
 447#ifdef CONFIG_TRACING
 448void tracing_on(void);
 449void tracing_off(void);
 450int tracing_is_on(void);
 451
 452extern void tracing_start(void);
 453extern void tracing_stop(void);
 454extern void ftrace_off_permanent(void);
 455
 456static inline __printf(1, 2)
 457void ____trace_printk_check_format(const char *fmt, ...)
 458{
 459}
 460#define __trace_printk_check_format(fmt, args...)                       \
 461do {                                                                    \
 462        if (0)                                                          \
 463                ____trace_printk_check_format(fmt, ##args);             \
 464} while (0)
 465
 466/**
 467 * trace_printk - printf formatting in the ftrace buffer
 468 * @fmt: the printf format for printing
 469 *
 470 * Note: __trace_printk is an internal function for trace_printk and
 471 *       the @ip is passed in via the trace_printk macro.
 472 *
 473 * This function allows a kernel developer to debug fast path sections
 474 * that printk is not appropriate for. By scattering in various
 475 * printk like tracing in the code, a developer can quickly see
 476 * where problems are occurring.
 477 *
 478 * This is intended as a debugging tool for the developer only.
 479 * Please refrain from leaving trace_printks scattered around in
 480 * your code.
 481 */
 482
 483#define trace_printk(fmt, args...)                                      \
 484do {                                                                    \
 485        static const char *trace_printk_fmt                             \
 486                __attribute__((section("__trace_printk_fmt"))) =        \
 487                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 488                                                                        \
 489        __trace_printk_check_format(fmt, ##args);                       \
 490                                                                        \
 491        if (__builtin_constant_p(fmt))                                  \
 492                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 493        else                                                            \
 494                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 495} while (0)
 496
 497extern __printf(2, 3)
 498int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 499
 500extern __printf(2, 3)
 501int __trace_printk(unsigned long ip, const char *fmt, ...);
 502
 503extern void trace_dump_stack(void);
 504
 505/*
 506 * The double __builtin_constant_p is because gcc will give us an error
 507 * if we try to allocate the static variable to fmt if it is not a
 508 * constant. Even with the outer if statement.
 509 */
 510#define ftrace_vprintk(fmt, vargs)                                      \
 511do {                                                                    \
 512        if (__builtin_constant_p(fmt)) {                                \
 513                static const char *trace_printk_fmt                     \
 514                  __attribute__((section("__trace_printk_fmt"))) =      \
 515                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 516                                                                        \
 517                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 518        } else                                                          \
 519                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 520} while (0)
 521
 522extern int
 523__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 524
 525extern int
 526__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 527
 528extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 529#else
 530static inline __printf(1, 2)
 531int trace_printk(const char *fmt, ...);
 532
 533static inline void tracing_start(void) { }
 534static inline void tracing_stop(void) { }
 535static inline void ftrace_off_permanent(void) { }
 536static inline void trace_dump_stack(void) { }
 537
 538static inline void tracing_on(void) { }
 539static inline void tracing_off(void) { }
 540static inline int tracing_is_on(void) { return 0; }
 541
 542static inline int
 543trace_printk(const char *fmt, ...)
 544{
 545        return 0;
 546}
 547static inline int
 548ftrace_vprintk(const char *fmt, va_list ap)
 549{
 550        return 0;
 551}
 552static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 553#endif /* CONFIG_TRACING */
 554
 555/*
 556 * min()/max()/clamp() macros that also do
 557 * strict type-checking.. See the
 558 * "unnecessary" pointer comparison.
 559 */
 560#define min(x, y) ({                            \
 561        typeof(x) _min1 = (x);                  \
 562        typeof(y) _min2 = (y);                  \
 563        (void) (&_min1 == &_min2);              \
 564        _min1 < _min2 ? _min1 : _min2; })
 565
 566#define max(x, y) ({                            \
 567        typeof(x) _max1 = (x);                  \
 568        typeof(y) _max2 = (y);                  \
 569        (void) (&_max1 == &_max2);              \
 570        _max1 > _max2 ? _max1 : _max2; })
 571
 572#define min3(x, y, z) ({                        \
 573        typeof(x) _min1 = (x);                  \
 574        typeof(y) _min2 = (y);                  \
 575        typeof(z) _min3 = (z);                  \
 576        (void) (&_min1 == &_min2);              \
 577        (void) (&_min1 == &_min3);              \
 578        _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
 579                (_min2 < _min3 ? _min2 : _min3); })
 580
 581#define max3(x, y, z) ({                        \
 582        typeof(x) _max1 = (x);                  \
 583        typeof(y) _max2 = (y);                  \
 584        typeof(z) _max3 = (z);                  \
 585        (void) (&_max1 == &_max2);              \
 586        (void) (&_max1 == &_max3);              \
 587        _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
 588                (_max2 > _max3 ? _max2 : _max3); })
 589
 590/**
 591 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 592 * @x: value1
 593 * @y: value2
 594 */
 595#define min_not_zero(x, y) ({                   \
 596        typeof(x) __x = (x);                    \
 597        typeof(y) __y = (y);                    \
 598        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 599
 600/**
 601 * clamp - return a value clamped to a given range with strict typechecking
 602 * @val: current value
 603 * @min: minimum allowable value
 604 * @max: maximum allowable value
 605 *
 606 * This macro does strict typechecking of min/max to make sure they are of the
 607 * same type as val.  See the unnecessary pointer comparisons.
 608 */
 609#define clamp(val, min, max) ({                 \
 610        typeof(val) __val = (val);              \
 611        typeof(min) __min = (min);              \
 612        typeof(max) __max = (max);              \
 613        (void) (&__val == &__min);              \
 614        (void) (&__val == &__max);              \
 615        __val = __val < __min ? __min: __val;   \
 616        __val > __max ? __max: __val; })
 617
 618/*
 619 * ..and if you can't take the strict
 620 * types, you can specify one yourself.
 621 *
 622 * Or not use min/max/clamp at all, of course.
 623 */
 624#define min_t(type, x, y) ({                    \
 625        type __min1 = (x);                      \
 626        type __min2 = (y);                      \
 627        __min1 < __min2 ? __min1: __min2; })
 628
 629#define max_t(type, x, y) ({                    \
 630        type __max1 = (x);                      \
 631        type __max2 = (y);                      \
 632        __max1 > __max2 ? __max1: __max2; })
 633
 634/**
 635 * clamp_t - return a value clamped to a given range using a given type
 636 * @type: the type of variable to use
 637 * @val: current value
 638 * @min: minimum allowable value
 639 * @max: maximum allowable value
 640 *
 641 * This macro does no typechecking and uses temporary variables of type
 642 * 'type' to make all the comparisons.
 643 */
 644#define clamp_t(type, val, min, max) ({         \
 645        type __val = (val);                     \
 646        type __min = (min);                     \
 647        type __max = (max);                     \
 648        __val = __val < __min ? __min: __val;   \
 649        __val > __max ? __max: __val; })
 650
 651/**
 652 * clamp_val - return a value clamped to a given range using val's type
 653 * @val: current value
 654 * @min: minimum allowable value
 655 * @max: maximum allowable value
 656 *
 657 * This macro does no typechecking and uses temporary variables of whatever
 658 * type the input argument 'val' is.  This is useful when val is an unsigned
 659 * type and min and max are literals that will otherwise be assigned a signed
 660 * integer type.
 661 */
 662#define clamp_val(val, min, max) ({             \
 663        typeof(val) __val = (val);              \
 664        typeof(val) __min = (min);              \
 665        typeof(val) __max = (max);              \
 666        __val = __val < __min ? __min: __val;   \
 667        __val > __max ? __max: __val; })
 668
 669
 670/*
 671 * swap - swap value of @a and @b
 672 */
 673#define swap(a, b) \
 674        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 675
 676/**
 677 * container_of - cast a member of a structure out to the containing structure
 678 * @ptr:        the pointer to the member.
 679 * @type:       the type of the container struct this is embedded in.
 680 * @member:     the name of the member within the struct.
 681 *
 682 */
 683#define container_of(ptr, type, member) ({                      \
 684        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 685        (type *)( (char *)__mptr - offsetof(type,member) );})
 686
 687/* Trap pasters of __FUNCTION__ at compile-time */
 688#define __FUNCTION__ (__func__)
 689
 690/* This helps us to avoid #ifdef CONFIG_NUMA */
 691#ifdef CONFIG_NUMA
 692#define NUMA_BUILD 1
 693#else
 694#define NUMA_BUILD 0
 695#endif
 696
 697/* This helps us avoid #ifdef CONFIG_COMPACTION */
 698#ifdef CONFIG_COMPACTION
 699#define COMPACTION_BUILD 1
 700#else
 701#define COMPACTION_BUILD 0
 702#endif
 703
 704/* This helps us to avoid #ifdef CONFIG_SYMBOL_PREFIX */
 705#ifdef CONFIG_SYMBOL_PREFIX
 706#define SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
 707#else
 708#define SYMBOL_PREFIX ""
 709#endif
 710
 711/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 712#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 713# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 714#endif
 715
 716extern int do_sysinfo(struct sysinfo *info);
 717
 718#endif
 719
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