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 and
  81 * for negative dividends if the divisor variable type is unsigned.
  82 */
  83#define DIV_ROUND_CLOSEST(x, divisor)(                  \
  84{                                                       \
  85        typeof(x) __x = x;                              \
  86        typeof(divisor) __d = divisor;                  \
  87        (((typeof(x))-1) > 0 ||                         \
  88         ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
  89                (((__x) + ((__d) / 2)) / (__d)) :       \
  90                (((__x) - ((__d) / 2)) / (__d));        \
  91}                                                       \
  92)
  93
  94/*
  95 * Multiplies an integer by a fraction, while avoiding unnecessary
  96 * overflow or loss of precision.
  97 */
  98#define mult_frac(x, numer, denom)(                     \
  99{                                                       \
 100        typeof(x) quot = (x) / (denom);                 \
 101        typeof(x) rem  = (x) % (denom);                 \
 102        (quot * (numer)) + ((rem * (numer)) / (denom)); \
 103}                                                       \
 104)
 105
 106
 107#define _RET_IP_                (unsigned long)__builtin_return_address(0)
 108#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })
 109
 110#ifdef CONFIG_LBDAF
 111# include <asm/div64.h>
 112# define sector_div(a, b) do_div(a, b)
 113#else
 114# define sector_div(n, b)( \
 115{ \
 116        int _res; \
 117        _res = (n) % (b); \
 118        (n) /= (b); \
 119        _res; \
 120} \
 121)
 122#endif
 123
 124/**
 125 * upper_32_bits - return bits 32-63 of a number
 126 * @n: the number we're accessing
 127 *
 128 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 129 * the "right shift count >= width of type" warning when that quantity is
 130 * 32-bits.
 131 */
 132#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))
 133
 134/**
 135 * lower_32_bits - return bits 0-31 of a number
 136 * @n: the number we're accessing
 137 */
 138#define lower_32_bits(n) ((u32)(n))
 139
 140struct completion;
 141struct pt_regs;
 142struct user;
 143
 144#ifdef CONFIG_PREEMPT_VOLUNTARY
 145extern int _cond_resched(void);
 146# define might_resched() _cond_resched()
 147#else
 148# define might_resched() do { } while (0)
 149#endif
 150
 151#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
 152  void __might_sleep(const char *file, int line, int preempt_offset);
 153/**
 154 * might_sleep - annotation for functions that can sleep
 155 *
 156 * this macro will print a stack trace if it is executed in an atomic
 157 * context (spinlock, irq-handler, ...).
 158 *
 159 * This is a useful debugging help to be able to catch problems early and not
 160 * be bitten later when the calling function happens to sleep when it is not
 161 * supposed to.
 162 */
 163# define might_sleep() \
 164        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
 165#else
 166  static inline void __might_sleep(const char *file, int line,
 167                                   int preempt_offset) { }
 168# define might_sleep() do { might_resched(); } while (0)
 169#endif
 170
 171#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
 172
 173/*
 174 * abs() handles unsigned and signed longs, ints, shorts and chars.  For all
 175 * input types abs() returns a signed long.
 176 * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
 177 * for those.
 178 */
 179#define abs(x) ({                                               \
 180                long ret;                                       \
 181                if (sizeof(x) == sizeof(long)) {                \
 182                        long __x = (x);                         \
 183                        ret = (__x < 0) ? -__x : __x;           \
 184                } else {                                        \
 185                        int __x = (x);                          \
 186                        ret = (__x < 0) ? -__x : __x;           \
 187                }                                               \
 188                ret;                                            \
 189        })
 190
 191#define abs64(x) ({                             \
 192                s64 __x = (x);                  \
 193                (__x < 0) ? -__x : __x;         \
 194        })
 195
 196#ifdef CONFIG_PROVE_LOCKING
 197void might_fault(void);
 198#else
 199static inline void might_fault(void)
 200{
 201        might_sleep();
 202}
 203#endif
 204
 205extern struct atomic_notifier_head panic_notifier_list;
 206extern long (*panic_blink)(int state);
 207__printf(1, 2)
 208void panic(const char *fmt, ...)
 209        __noreturn __cold;
 210extern void oops_enter(void);
 211extern void oops_exit(void);
 212void print_oops_end_marker(void);
 213extern int oops_may_print(void);
 214void do_exit(long error_code)
 215        __noreturn;
 216void complete_and_exit(struct completion *, long)
 217        __noreturn;
 218
 219/* Internal, do not use. */
 220int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
 221int __must_check _kstrtol(const char *s, unsigned int base, long *res);
 222
 223int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
 224int __must_check kstrtoll(const char *s, unsigned int base, long long *res);
 225
 226/**
 227 * kstrtoul - convert a string to an unsigned long
 228 * @s: The start of the string. The string must be null-terminated, and may also
 229 *  include a single newline before its terminating null. The first character
 230 *  may also be a plus sign, but not a minus sign.
 231 * @base: The number base to use. The maximum supported base is 16. If base is
 232 *  given as 0, then the base of the string is automatically detected with the
 233 *  conventional semantics - If it begins with 0x the number will be parsed as a
 234 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 235 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 236 * @res: Where to write the result of the conversion on success.
 237 *
 238 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 239 * Used as a replacement for the obsolete simple_strtoull. Return code must
 240 * be checked.
 241*/
 242static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
 243{
 244        /*
 245         * We want to shortcut function call, but
 246         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
 247         */
 248        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
 249            __alignof__(unsigned long) == __alignof__(unsigned long long))
 250                return kstrtoull(s, base, (unsigned long long *)res);
 251        else
 252                return _kstrtoul(s, base, res);
 253}
 254
 255/**
 256 * kstrtol - convert a string to a long
 257 * @s: The start of the string. The string must be null-terminated, and may also
 258 *  include a single newline before its terminating null. The first character
 259 *  may also be a plus sign or a minus sign.
 260 * @base: The number base to use. The maximum supported base is 16. If base is
 261 *  given as 0, then the base of the string is automatically detected with the
 262 *  conventional semantics - If it begins with 0x the number will be parsed as a
 263 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 264 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 265 * @res: Where to write the result of the conversion on success.
 266 *
 267 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 268 * Used as a replacement for the obsolete simple_strtoull. Return code must
 269 * be checked.
 270 */
 271static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
 272{
 273        /*
 274         * We want to shortcut function call, but
 275         * __builtin_types_compatible_p(long, long long) = 0.
 276         */
 277        if (sizeof(long) == sizeof(long long) &&
 278            __alignof__(long) == __alignof__(long long))
 279                return kstrtoll(s, base, (long long *)res);
 280        else
 281                return _kstrtol(s, base, res);
 282}
 283
 284int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
 285int __must_check kstrtoint(const char *s, unsigned int base, int *res);
 286
 287static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
 288{
 289        return kstrtoull(s, base, res);
 290}
 291
 292static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
 293{
 294        return kstrtoll(s, base, res);
 295}
 296
 297static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
 298{
 299        return kstrtouint(s, base, res);
 300}
 301
 302static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
 303{
 304        return kstrtoint(s, base, res);
 305}
 306
 307int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
 308int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
 309int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
 310int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);
 311
 312int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
 313int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
 314int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
 315int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
 316int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
 317int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
 318int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
 319int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
 320int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
 321int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);
 322
 323static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
 324{
 325        return kstrtoull_from_user(s, count, base, res);
 326}
 327
 328static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
 329{
 330        return kstrtoll_from_user(s, count, base, res);
 331}
 332
 333static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
 334{
 335        return kstrtouint_from_user(s, count, base, res);
 336}
 337
 338static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
 339{
 340        return kstrtoint_from_user(s, count, base, res);
 341}
 342
 343/* Obsolete, do not use.  Use kstrto<foo> instead */
 344
 345extern unsigned long simple_strtoul(const char *,char **,unsigned int);
 346extern long simple_strtol(const char *,char **,unsigned int);
 347extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
 348extern long long simple_strtoll(const char *,char **,unsigned int);
 349#define strict_strtoul  kstrtoul
 350#define strict_strtol   kstrtol
 351#define strict_strtoull kstrtoull
 352#define strict_strtoll  kstrtoll
 353
 354extern int num_to_str(char *buf, int size, unsigned long long num);
 355
 356/* lib/printf utilities */
 357
 358extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
 359extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
 360extern __printf(3, 4)
 361int snprintf(char *buf, size_t size, const char *fmt, ...);
 362extern __printf(3, 0)
 363int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
 364extern __printf(3, 4)
 365int scnprintf(char *buf, size_t size, const char *fmt, ...);
 366extern __printf(3, 0)
 367int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
 368extern __printf(2, 3)
 369char *kasprintf(gfp_t gfp, const char *fmt, ...);
 370extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
 371
 372extern __scanf(2, 3)
 373int sscanf(const char *, const char *, ...);
 374extern __scanf(2, 0)
 375int vsscanf(const char *, const char *, va_list);
 376
 377extern int get_option(char **str, int *pint);
 378extern char *get_options(const char *str, int nints, int *ints);
 379extern unsigned long long memparse(const char *ptr, char **retptr);
 380
 381extern int core_kernel_text(unsigned long addr);
 382extern int core_kernel_data(unsigned long addr);
 383extern int __kernel_text_address(unsigned long addr);
 384extern int kernel_text_address(unsigned long addr);
 385extern int func_ptr_is_kernel_text(void *ptr);
 386
 387struct pid;
 388extern struct pid *session_of_pgrp(struct pid *pgrp);
 389
 390unsigned long int_sqrt(unsigned long);
 391
 392extern void bust_spinlocks(int yes);
 393extern void wake_up_klogd(void);
 394extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
 395extern int panic_timeout;
 396extern int panic_on_oops;
 397extern int panic_on_unrecovered_nmi;
 398extern int panic_on_io_nmi;
 399extern int sysctl_panic_on_stackoverflow;
 400extern const char *print_tainted(void);
 401extern void add_taint(unsigned flag);
 402extern int test_taint(unsigned flag);
 403extern unsigned long get_taint(void);
 404extern int root_mountflags;
 405
 406extern bool early_boot_irqs_disabled;
 407
 408/* Values used for system_state */
 409extern enum system_states {
 410        SYSTEM_BOOTING,
 411        SYSTEM_RUNNING,
 412        SYSTEM_HALT,
 413        SYSTEM_POWER_OFF,
 414        SYSTEM_RESTART,
 415} system_state;
 416
 417#define TAINT_PROPRIETARY_MODULE        0
 418#define TAINT_FORCED_MODULE             1
 419#define TAINT_UNSAFE_SMP                2
 420#define TAINT_FORCED_RMMOD              3
 421#define TAINT_MACHINE_CHECK             4
 422#define TAINT_BAD_PAGE                  5
 423#define TAINT_USER                      6
 424#define TAINT_DIE                       7
 425#define TAINT_OVERRIDDEN_ACPI_TABLE     8
 426#define TAINT_WARN                      9
 427#define TAINT_CRAP                      10
 428#define TAINT_FIRMWARE_WORKAROUND       11
 429#define TAINT_OOT_MODULE                12
 430
 431extern const char hex_asc[];
 432#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
 433#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
 434
 435static inline char *hex_byte_pack(char *buf, u8 byte)
 436{
 437        *buf++ = hex_asc_hi(byte);
 438        *buf++ = hex_asc_lo(byte);
 439        return buf;
 440}
 441
 442static inline char * __deprecated pack_hex_byte(char *buf, u8 byte)
 443{
 444        return hex_byte_pack(buf, byte);
 445}
 446
 447extern int hex_to_bin(char ch);
 448extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
 449
 450/*
 451 * General tracing related utility functions - trace_printk(),
 452 * tracing_on/tracing_off and tracing_start()/tracing_stop
 453 *
 454 * Use tracing_on/tracing_off when you want to quickly turn on or off
 455 * tracing. It simply enables or disables the recording of the trace events.
 456 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 457 * file, which gives a means for the kernel and userspace to interact.
 458 * Place a tracing_off() in the kernel where you want tracing to end.
 459 * From user space, examine the trace, and then echo 1 > tracing_on
 460 * to continue tracing.
 461 *
 462 * tracing_stop/tracing_start has slightly more overhead. It is used
 463 * by things like suspend to ram where disabling the recording of the
 464 * trace is not enough, but tracing must actually stop because things
 465 * like calling smp_processor_id() may crash the system.
 466 *
 467 * Most likely, you want to use tracing_on/tracing_off.
 468 */
 469#ifdef CONFIG_RING_BUFFER
 470/* trace_off_permanent stops recording with no way to bring it back */
 471void tracing_off_permanent(void);
 472#else
 473static inline void tracing_off_permanent(void) { }
 474#endif
 475
 476enum ftrace_dump_mode {
 477        DUMP_NONE,
 478        DUMP_ALL,
 479        DUMP_ORIG,
 480};
 481
 482#ifdef CONFIG_TRACING
 483void tracing_on(void);
 484void tracing_off(void);
 485int tracing_is_on(void);
 486
 487extern void tracing_start(void);
 488extern void tracing_stop(void);
 489extern void ftrace_off_permanent(void);
 490
 491static inline __printf(1, 2)
 492void ____trace_printk_check_format(const char *fmt, ...)
 493{
 494}
 495#define __trace_printk_check_format(fmt, args...)                       \
 496do {                                                                    \
 497        if (0)                                                          \
 498                ____trace_printk_check_format(fmt, ##args);             \
 499} while (0)
 500
 501/**
 502 * trace_printk - printf formatting in the ftrace buffer
 503 * @fmt: the printf format for printing
 504 *
 505 * Note: __trace_printk is an internal function for trace_printk and
 506 *       the @ip is passed in via the trace_printk macro.
 507 *
 508 * This function allows a kernel developer to debug fast path sections
 509 * that printk is not appropriate for. By scattering in various
 510 * printk like tracing in the code, a developer can quickly see
 511 * where problems are occurring.
 512 *
 513 * This is intended as a debugging tool for the developer only.
 514 * Please refrain from leaving trace_printks scattered around in
 515 * your code.
 516 */
 517
 518#define trace_printk(fmt, args...)                                      \
 519do {                                                                    \
 520        static const char *trace_printk_fmt                             \
 521                __attribute__((section("__trace_printk_fmt"))) =        \
 522                __builtin_constant_p(fmt) ? fmt : NULL;                 \
 523                                                                        \
 524        __trace_printk_check_format(fmt, ##args);                       \
 525                                                                        \
 526        if (__builtin_constant_p(fmt))                                  \
 527                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
 528        else                                                            \
 529                __trace_printk(_THIS_IP_, fmt, ##args);                 \
 530} while (0)
 531
 532extern __printf(2, 3)
 533int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 534
 535extern __printf(2, 3)
 536int __trace_printk(unsigned long ip, const char *fmt, ...);
 537
 538extern void trace_dump_stack(void);
 539
 540/*
 541 * The double __builtin_constant_p is because gcc will give us an error
 542 * if we try to allocate the static variable to fmt if it is not a
 543 * constant. Even with the outer if statement.
 544 */
 545#define ftrace_vprintk(fmt, vargs)                                      \
 546do {                                                                    \
 547        if (__builtin_constant_p(fmt)) {                                \
 548                static const char *trace_printk_fmt                     \
 549                  __attribute__((section("__trace_printk_fmt"))) =      \
 550                        __builtin_constant_p(fmt) ? fmt : NULL;         \
 551                                                                        \
 552                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
 553        } else                                                          \
 554                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
 555} while (0)
 556
 557extern int
 558__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);
 559
 560extern int
 561__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 562
 563extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 564#else
 565static inline void tracing_start(void) { }
 566static inline void tracing_stop(void) { }
 567static inline void ftrace_off_permanent(void) { }
 568static inline void trace_dump_stack(void) { }
 569
 570static inline void tracing_on(void) { }
 571static inline void tracing_off(void) { }
 572static inline int tracing_is_on(void) { return 0; }
 573
 574static inline __printf(1, 2)
 575int trace_printk(const char *fmt, ...)
 576{
 577        return 0;
 578}
 579static inline int
 580ftrace_vprintk(const char *fmt, va_list ap)
 581{
 582        return 0;
 583}
 584static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 585#endif /* CONFIG_TRACING */
 586
 587/*
 588 * min()/max()/clamp() macros that also do
 589 * strict type-checking.. See the
 590 * "unnecessary" pointer comparison.
 591 */
 592#define min(x, y) ({                            \
 593        typeof(x) _min1 = (x);                  \
 594        typeof(y) _min2 = (y);                  \
 595        (void) (&_min1 == &_min2);              \
 596        _min1 < _min2 ? _min1 : _min2; })
 597
 598#define max(x, y) ({                            \
 599        typeof(x) _max1 = (x);                  \
 600        typeof(y) _max2 = (y);                  \
 601        (void) (&_max1 == &_max2);              \
 602        _max1 > _max2 ? _max1 : _max2; })
 603
 604#define min3(x, y, z) ({                        \
 605        typeof(x) _min1 = (x);                  \
 606        typeof(y) _min2 = (y);                  \
 607        typeof(z) _min3 = (z);                  \
 608        (void) (&_min1 == &_min2);              \
 609        (void) (&_min1 == &_min3);              \
 610        _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
 611                (_min2 < _min3 ? _min2 : _min3); })
 612
 613#define max3(x, y, z) ({                        \
 614        typeof(x) _max1 = (x);                  \
 615        typeof(y) _max2 = (y);                  \
 616        typeof(z) _max3 = (z);                  \
 617        (void) (&_max1 == &_max2);              \
 618        (void) (&_max1 == &_max3);              \
 619        _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
 620                (_max2 > _max3 ? _max2 : _max3); })
 621
 622/**
 623 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 624 * @x: value1
 625 * @y: value2
 626 */
 627#define min_not_zero(x, y) ({                   \
 628        typeof(x) __x = (x);                    \
 629        typeof(y) __y = (y);                    \
 630        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
 631
 632/**
 633 * clamp - return a value clamped to a given range with strict typechecking
 634 * @val: current value
 635 * @min: minimum allowable value
 636 * @max: maximum allowable value
 637 *
 638 * This macro does strict typechecking of min/max to make sure they are of the
 639 * same type as val.  See the unnecessary pointer comparisons.
 640 */
 641#define clamp(val, min, max) ({                 \
 642        typeof(val) __val = (val);              \
 643        typeof(min) __min = (min);              \
 644        typeof(max) __max = (max);              \
 645        (void) (&__val == &__min);              \
 646        (void) (&__val == &__max);              \
 647        __val = __val < __min ? __min: __val;   \
 648        __val > __max ? __max: __val; })
 649
 650/*
 651 * ..and if you can't take the strict
 652 * types, you can specify one yourself.
 653 *
 654 * Or not use min/max/clamp at all, of course.
 655 */
 656#define min_t(type, x, y) ({                    \
 657        type __min1 = (x);                      \
 658        type __min2 = (y);                      \
 659        __min1 < __min2 ? __min1: __min2; })
 660
 661#define max_t(type, x, y) ({                    \
 662        type __max1 = (x);                      \
 663        type __max2 = (y);                      \
 664        __max1 > __max2 ? __max1: __max2; })
 665
 666/**
 667 * clamp_t - return a value clamped to a given range using a given type
 668 * @type: the type of variable to use
 669 * @val: current value
 670 * @min: minimum allowable value
 671 * @max: maximum allowable value
 672 *
 673 * This macro does no typechecking and uses temporary variables of type
 674 * 'type' to make all the comparisons.
 675 */
 676#define clamp_t(type, val, min, max) ({         \
 677        type __val = (val);                     \
 678        type __min = (min);                     \
 679        type __max = (max);                     \
 680        __val = __val < __min ? __min: __val;   \
 681        __val > __max ? __max: __val; })
 682
 683/**
 684 * clamp_val - return a value clamped to a given range using val's type
 685 * @val: current value
 686 * @min: minimum allowable value
 687 * @max: maximum allowable value
 688 *
 689 * This macro does no typechecking and uses temporary variables of whatever
 690 * type the input argument 'val' is.  This is useful when val is an unsigned
 691 * type and min and max are literals that will otherwise be assigned a signed
 692 * integer type.
 693 */
 694#define clamp_val(val, min, max) ({             \
 695        typeof(val) __val = (val);              \
 696        typeof(val) __min = (min);              \
 697        typeof(val) __max = (max);              \
 698        __val = __val < __min ? __min: __val;   \
 699        __val > __max ? __max: __val; })
 700
 701
 702/*
 703 * swap - swap value of @a and @b
 704 */
 705#define swap(a, b) \
 706        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
 707
 708/**
 709 * container_of - cast a member of a structure out to the containing structure
 710 * @ptr:        the pointer to the member.
 711 * @type:       the type of the container struct this is embedded in.
 712 * @member:     the name of the member within the struct.
 713 *
 714 */
 715#define container_of(ptr, type, member) ({                      \
 716        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 717        (type *)( (char *)__mptr - offsetof(type,member) );})
 718
 719/* Trap pasters of __FUNCTION__ at compile-time */
 720#define __FUNCTION__ (__func__)
 721
 722/* This helps us to avoid #ifdef CONFIG_SYMBOL_PREFIX */
 723#ifdef CONFIG_SYMBOL_PREFIX
 724#define SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
 725#else
 726#define SYMBOL_PREFIX ""
 727#endif
 728
 729/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
 730#ifdef CONFIG_FTRACE_MCOUNT_RECORD
 731# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
 732#endif
 733
 734extern int do_sysinfo(struct sysinfo *info);
 735
 736#endif
 737
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