Merge branch 'drm-sti-next-2015-11-03' of http://git.linaro.org/people/benjamin.gaign...

[mirror_ubuntu-artful-kernel.git] / include / linux / kernel.h

#ifndef _LINUX_KERNEL_H
#define _LINUX_KERNEL_H


#include <stdarg.h>
#include <linux/linkage.h>
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/bitops.h>
#include <linux/log2.h>
#include <linux/typecheck.h>
#include <linux/printk.h>
#include <linux/dynamic_debug.h>
#include <asm/byteorder.h>
#include <uapi/linux/kernel.h>

#define USHRT_MAX       ((u16)(~0U))
#define SHRT_MAX        ((s16)(USHRT_MAX>>1))
#define SHRT_MIN        ((s16)(-SHRT_MAX - 1))
#define INT_MAX         ((int)(~0U>>1))
#define INT_MIN         (-INT_MAX - 1)
#define UINT_MAX        (~0U)
#define LONG_MAX        ((long)(~0UL>>1))
#define LONG_MIN        (-LONG_MAX - 1)
#define ULONG_MAX       (~0UL)
#define LLONG_MAX       ((long long)(~0ULL>>1))
#define LLONG_MIN       (-LLONG_MAX - 1)
#define ULLONG_MAX      (~0ULL)
#define SIZE_MAX        (~(size_t)0)

#define U8_MAX          ((u8)~0U)
#define S8_MAX          ((s8)(U8_MAX>>1))
#define S8_MIN          ((s8)(-S8_MAX - 1))
#define U16_MAX         ((u16)~0U)
#define S16_MAX         ((s16)(U16_MAX>>1))
#define S16_MIN         ((s16)(-S16_MAX - 1))
#define U32_MAX         ((u32)~0U)
#define S32_MAX         ((s32)(U32_MAX>>1))
#define S32_MIN         ((s32)(-S32_MAX - 1))
#define U64_MAX         ((u64)~0ULL)
#define S64_MAX         ((s64)(U64_MAX>>1))
#define S64_MIN         ((s64)(-S64_MAX - 1))

#define STACK_MAGIC     0xdeadbeef

#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))

#define ALIGN(x, a)             __ALIGN_KERNEL((x), (a))
#define __ALIGN_MASK(x, mask)   __ALIGN_KERNEL_MASK((x), (mask))
#define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
#define IS_ALIGNED(x, a)                (((x) & ((typeof(x))(a) - 1)) == 0)

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))

/*
 * This looks more complex than it should be. But we need to
 * get the type for the ~ right in round_down (it needs to be
 * as wide as the result!), and we want to evaluate the macro
 * arguments just once each.
 */
#define __round_mask(x, y) ((__typeof__(x))((y)-1))
#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
#define round_down(x, y) ((x) & ~__round_mask(x, y))

#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define DIV_ROUND_UP_ULL(ll,d) \
        ({ unsigned long long _tmp = (ll)+(d)-1; do_div(_tmp, d); _tmp; })

#if BITS_PER_LONG == 32
# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
#else
# define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP(ll,d)
#endif

/* The `const' in roundup() prevents gcc-3.3 from calling __divdi3 */
#define roundup(x, y) (                                 \
{                                                       \
        const typeof(y) __y = y;                        \
        (((x) + (__y - 1)) / __y) * __y;                \
}                                                       \
)
#define rounddown(x, y) (                               \
{                                                       \
        typeof(x) __x = (x);                            \
        __x - (__x % (y));                              \
}                                                       \
)

/*
 * Divide positive or negative dividend by positive divisor and round
 * to closest integer. Result is undefined for negative divisors and
 * for negative dividends if the divisor variable type is unsigned.
 */
#define DIV_ROUND_CLOSEST(x, divisor)(                  \
{                                                       \
        typeof(x) __x = x;                              \
        typeof(divisor) __d = divisor;                  \
        (((typeof(x))-1) > 0 ||                         \
         ((typeof(divisor))-1) > 0 || (__x) > 0) ?      \
                (((__x) + ((__d) / 2)) / (__d)) :       \
                (((__x) - ((__d) / 2)) / (__d));        \
}                                                       \
)
/*
 * Same as above but for u64 dividends. divisor must be a 32-bit
 * number.
 */
#define DIV_ROUND_CLOSEST_ULL(x, divisor)(              \
{                                                       \
        typeof(divisor) __d = divisor;                  \
        unsigned long long _tmp = (x) + (__d) / 2;      \
        do_div(_tmp, __d);                              \
        _tmp;                                           \
}                                                       \
)

/*
 * Multiplies an integer by a fraction, while avoiding unnecessary
 * overflow or loss of precision.
 */
#define mult_frac(x, numer, denom)(                     \
{                                                       \
        typeof(x) quot = (x) / (denom);                 \
        typeof(x) rem  = (x) % (denom);                 \
        (quot * (numer)) + ((rem * (numer)) / (denom)); \
}                                                       \
)


#define _RET_IP_                (unsigned long)__builtin_return_address(0)
#define _THIS_IP_  ({ __label__ __here; __here: (unsigned long)&&__here; })

#ifdef CONFIG_LBDAF
# include <asm/div64.h>
# define sector_div(a, b) do_div(a, b)
#else
# define sector_div(n, b)( \
{ \
        int _res; \
        _res = (n) % (b); \
        (n) /= (b); \
        _res; \
} \
)
#endif

/**
 * upper_32_bits - return bits 32-63 of a number
 * @n: the number we're accessing
 *
 * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
 * the "right shift count >= width of type" warning when that quantity is
 * 32-bits.
 */
#define upper_32_bits(n) ((u32)(((n) >> 16) >> 16))

/**
 * lower_32_bits - return bits 0-31 of a number
 * @n: the number we're accessing
 */
#define lower_32_bits(n) ((u32)(n))

struct completion;
struct pt_regs;
struct user;

#ifdef CONFIG_PREEMPT_VOLUNTARY
extern int _cond_resched(void);
# define might_resched() _cond_resched()
#else
# define might_resched() do { } while (0)
#endif

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  void ___might_sleep(const char *file, int line, int preempt_offset);
  void __might_sleep(const char *file, int line, int preempt_offset);
/**
 * might_sleep - annotation for functions that can sleep
 *
 * this macro will print a stack trace if it is executed in an atomic
 * context (spinlock, irq-handler, ...).
 *
 * This is a useful debugging help to be able to catch problems early and not
 * be bitten later when the calling function happens to sleep when it is not
 * supposed to.
 */
# define might_sleep() \
        do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
# define sched_annotate_sleep() (current->task_state_change = 0)
#else
  static inline void ___might_sleep(const char *file, int line,
                                   int preempt_offset) { }
  static inline void __might_sleep(const char *file, int line,
                                   int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
# define sched_annotate_sleep() do { } while (0)
#endif

#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)

/**
 * abs - return absolute value of an argument
 * @x: the value.  If it is unsigned type, it is converted to signed type first
 *   (s64, long or int depending on its size).
 *
 * Return: an absolute value of x.  If x is 64-bit, macro's return type is s64,
 *   otherwise it is signed long.
 */
#define abs(x) __builtin_choose_expr(sizeof(x) == sizeof(s64), ({       \
                s64 __x = (x);                                          \
                (__x < 0) ? -__x : __x;                                 \
        }), ({                                                          \
                long ret;                                               \
                if (sizeof(x) == sizeof(long)) {                        \
                        long __x = (x);                                 \
                        ret = (__x < 0) ? -__x : __x;                   \
                } else {                                                \
                        int __x = (x);                                  \
                        ret = (__x < 0) ? -__x : __x;                   \
                }                                                       \
                ret;                                                    \
        }))

/**
 * reciprocal_scale - "scale" a value into range [0, ep_ro)
 * @val: value
 * @ep_ro: right open interval endpoint
 *
 * Perform a "reciprocal multiplication" in order to "scale" a value into
 * range [0, ep_ro), where the upper interval endpoint is right-open.
 * This is useful, e.g. for accessing a index of an array containing
 * ep_ro elements, for example. Think of it as sort of modulus, only that
 * the result isn't that of modulo. ;) Note that if initial input is a
 * small value, then result will return 0.
 *
 * Return: a result based on val in interval [0, ep_ro).
 */
static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
{
        return (u32)(((u64) val * ep_ro) >> 32);
}

#if defined(CONFIG_MMU) && \
        (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
#define might_fault() __might_fault(__FILE__, __LINE__)
void __might_fault(const char *file, int line);
#else
static inline void might_fault(void) { }
#endif

extern struct atomic_notifier_head panic_notifier_list;
extern long (*panic_blink)(int state);
__printf(1, 2)
void panic(const char *fmt, ...)
        __noreturn __cold;
extern void oops_enter(void);
extern void oops_exit(void);
void print_oops_end_marker(void);
extern int oops_may_print(void);
void do_exit(long error_code)
        __noreturn;
void complete_and_exit(struct completion *, long)
        __noreturn;

/* Internal, do not use. */
int __must_check _kstrtoul(const char *s, unsigned int base, unsigned long *res);
int __must_check _kstrtol(const char *s, unsigned int base, long *res);

int __must_check kstrtoull(const char *s, unsigned int base, unsigned long long *res);
int __must_check kstrtoll(const char *s, unsigned int base, long long *res);

/**
 * kstrtoul - convert a string to an unsigned long
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign, but not a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Used as a replacement for the obsolete simple_strtoull. Return code must
 * be checked.
*/
static inline int __must_check kstrtoul(const char *s, unsigned int base, unsigned long *res)
{
        /*
         * We want to shortcut function call, but
         * __builtin_types_compatible_p(unsigned long, unsigned long long) = 0.
         */
        if (sizeof(unsigned long) == sizeof(unsigned long long) &&
            __alignof__(unsigned long) == __alignof__(unsigned long long))
                return kstrtoull(s, base, (unsigned long long *)res);
        else
                return _kstrtoul(s, base, res);
}

/**
 * kstrtol - convert a string to a long
 * @s: The start of the string. The string must be null-terminated, and may also
 *  include a single newline before its terminating null. The first character
 *  may also be a plus sign or a minus sign.
 * @base: The number base to use. The maximum supported base is 16. If base is
 *  given as 0, then the base of the string is automatically detected with the
 *  conventional semantics - If it begins with 0x the number will be parsed as a
 *  hexadecimal (case insensitive), if it otherwise begins with 0, it will be
 *  parsed as an octal number. Otherwise it will be parsed as a decimal.
 * @res: Where to write the result of the conversion on success.
 *
 * Returns 0 on success, -ERANGE on overflow and -EINVAL on parsing error.
 * Used as a replacement for the obsolete simple_strtoull. Return code must
 * be checked.
 */
static inline int __must_check kstrtol(const char *s, unsigned int base, long *res)
{
        /*
         * We want to shortcut function call, but
         * __builtin_types_compatible_p(long, long long) = 0.
         */
        if (sizeof(long) == sizeof(long long) &&
            __alignof__(long) == __alignof__(long long))
                return kstrtoll(s, base, (long long *)res);
        else
                return _kstrtol(s, base, res);
}

int __must_check kstrtouint(const char *s, unsigned int base, unsigned int *res);
int __must_check kstrtoint(const char *s, unsigned int base, int *res);

static inline int __must_check kstrtou64(const char *s, unsigned int base, u64 *res)
{
        return kstrtoull(s, base, res);
}

static inline int __must_check kstrtos64(const char *s, unsigned int base, s64 *res)
{
        return kstrtoll(s, base, res);
}

static inline int __must_check kstrtou32(const char *s, unsigned int base, u32 *res)
{
        return kstrtouint(s, base, res);
}

static inline int __must_check kstrtos32(const char *s, unsigned int base, s32 *res)
{
        return kstrtoint(s, base, res);
}

int __must_check kstrtou16(const char *s, unsigned int base, u16 *res);
int __must_check kstrtos16(const char *s, unsigned int base, s16 *res);
int __must_check kstrtou8(const char *s, unsigned int base, u8 *res);
int __must_check kstrtos8(const char *s, unsigned int base, s8 *res);

int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
int __must_check kstrtol_from_user(const char __user *s, size_t count, unsigned int base, long *res);
int __must_check kstrtouint_from_user(const char __user *s, size_t count, unsigned int base, unsigned int *res);
int __must_check kstrtoint_from_user(const char __user *s, size_t count, unsigned int base, int *res);
int __must_check kstrtou16_from_user(const char __user *s, size_t count, unsigned int base, u16 *res);
int __must_check kstrtos16_from_user(const char __user *s, size_t count, unsigned int base, s16 *res);
int __must_check kstrtou8_from_user(const char __user *s, size_t count, unsigned int base, u8 *res);
int __must_check kstrtos8_from_user(const char __user *s, size_t count, unsigned int base, s8 *res);

static inline int __must_check kstrtou64_from_user(const char __user *s, size_t count, unsigned int base, u64 *res)
{
        return kstrtoull_from_user(s, count, base, res);
}

static inline int __must_check kstrtos64_from_user(const char __user *s, size_t count, unsigned int base, s64 *res)
{
        return kstrtoll_from_user(s, count, base, res);
}

static inline int __must_check kstrtou32_from_user(const char __user *s, size_t count, unsigned int base, u32 *res)
{
        return kstrtouint_from_user(s, count, base, res);
}

static inline int __must_check kstrtos32_from_user(const char __user *s, size_t count, unsigned int base, s32 *res)
{
        return kstrtoint_from_user(s, count, base, res);
}

/* Obsolete, do not use.  Use kstrto<foo> instead */

extern unsigned long simple_strtoul(const char *,char **,unsigned int);
extern long simple_strtol(const char *,char **,unsigned int);
extern unsigned long long simple_strtoull(const char *,char **,unsigned int);
extern long long simple_strtoll(const char *,char **,unsigned int);

extern int num_to_str(char *buf, int size, unsigned long long num);

/* lib/printf utilities */

extern __printf(2, 3) int sprintf(char *buf, const char * fmt, ...);
extern __printf(2, 0) int vsprintf(char *buf, const char *, va_list);
extern __printf(3, 4)
int snprintf(char *buf, size_t size, const char *fmt, ...);
extern __printf(3, 0)
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
extern __printf(3, 4)
int scnprintf(char *buf, size_t size, const char *fmt, ...);
extern __printf(3, 0)
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
extern __printf(2, 3)
char *kasprintf(gfp_t gfp, const char *fmt, ...);
extern __printf(2, 0)
char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
extern __printf(2, 0)
const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list args);

extern __scanf(2, 3)
int sscanf(const char *, const char *, ...);
extern __scanf(2, 0)
int vsscanf(const char *, const char *, va_list);

extern int get_option(char **str, int *pint);
extern char *get_options(const char *str, int nints, int *ints);
extern unsigned long long memparse(const char *ptr, char **retptr);
extern bool parse_option_str(const char *str, const char *option);

extern int core_kernel_text(unsigned long addr);
extern int core_kernel_data(unsigned long addr);
extern int __kernel_text_address(unsigned long addr);
extern int kernel_text_address(unsigned long addr);
extern int func_ptr_is_kernel_text(void *ptr);

unsigned long int_sqrt(unsigned long);

extern void bust_spinlocks(int yes);
extern int oops_in_progress;            /* If set, an oops, panic(), BUG() or die() is in progress */
extern int panic_timeout;
extern int panic_on_oops;
extern int panic_on_unrecovered_nmi;
extern int panic_on_io_nmi;
extern int panic_on_warn;
extern int sysctl_panic_on_stackoverflow;

extern bool crash_kexec_post_notifiers;

/*
 * Only to be used by arch init code. If the user over-wrote the default
 * CONFIG_PANIC_TIMEOUT, honor it.
 */
static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
{
        if (panic_timeout == arch_default_timeout)
                panic_timeout = timeout;
}
extern const char *print_tainted(void);
enum lockdep_ok {
        LOCKDEP_STILL_OK,
        LOCKDEP_NOW_UNRELIABLE
};
extern void add_taint(unsigned flag, enum lockdep_ok);
extern int test_taint(unsigned flag);
extern unsigned long get_taint(void);
extern int root_mountflags;

extern bool early_boot_irqs_disabled;

/* Values used for system_state */
extern enum system_states {
        SYSTEM_BOOTING,
        SYSTEM_RUNNING,
        SYSTEM_HALT,
        SYSTEM_POWER_OFF,
        SYSTEM_RESTART,
} system_state;

#define TAINT_PROPRIETARY_MODULE        0
#define TAINT_FORCED_MODULE             1
#define TAINT_CPU_OUT_OF_SPEC           2
#define TAINT_FORCED_RMMOD              3
#define TAINT_MACHINE_CHECK             4
#define TAINT_BAD_PAGE                  5
#define TAINT_USER                      6
#define TAINT_DIE                       7
#define TAINT_OVERRIDDEN_ACPI_TABLE     8
#define TAINT_WARN                      9
#define TAINT_CRAP                      10
#define TAINT_FIRMWARE_WORKAROUND       11
#define TAINT_OOT_MODULE                12
#define TAINT_UNSIGNED_MODULE           13
#define TAINT_SOFTLOCKUP                14
#define TAINT_LIVEPATCH                 15

extern const char hex_asc[];
#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]

static inline char *hex_byte_pack(char *buf, u8 byte)
{
        *buf++ = hex_asc_hi(byte);
        *buf++ = hex_asc_lo(byte);
        return buf;
}

extern const char hex_asc_upper[];
#define hex_asc_upper_lo(x)     hex_asc_upper[((x) & 0x0f)]
#define hex_asc_upper_hi(x)     hex_asc_upper[((x) & 0xf0) >> 4]

static inline char *hex_byte_pack_upper(char *buf, u8 byte)
{
        *buf++ = hex_asc_upper_hi(byte);
        *buf++ = hex_asc_upper_lo(byte);
        return buf;
}

extern int hex_to_bin(char ch);
extern int __must_check hex2bin(u8 *dst, const char *src, size_t count);
extern char *bin2hex(char *dst, const void *src, size_t count);

bool mac_pton(const char *s, u8 *mac);

/*
 * General tracing related utility functions - trace_printk(),
 * tracing_on/tracing_off and tracing_start()/tracing_stop
 *
 * Use tracing_on/tracing_off when you want to quickly turn on or off
 * tracing. It simply enables or disables the recording of the trace events.
 * This also corresponds to the user space /sys/kernel/debug/tracing/tracing_on
 * file, which gives a means for the kernel and userspace to interact.
 * Place a tracing_off() in the kernel where you want tracing to end.
 * From user space, examine the trace, and then echo 1 > tracing_on
 * to continue tracing.
 *
 * tracing_stop/tracing_start has slightly more overhead. It is used
 * by things like suspend to ram where disabling the recording of the
 * trace is not enough, but tracing must actually stop because things
 * like calling smp_processor_id() may crash the system.
 *
 * Most likely, you want to use tracing_on/tracing_off.
 */

enum ftrace_dump_mode {
        DUMP_NONE,
        DUMP_ALL,
        DUMP_ORIG,
};

#ifdef CONFIG_TRACING
void tracing_on(void);
void tracing_off(void);
int tracing_is_on(void);
void tracing_snapshot(void);
void tracing_snapshot_alloc(void);

extern void tracing_start(void);
extern void tracing_stop(void);

static inline __printf(1, 2)
void ____trace_printk_check_format(const char *fmt, ...)
{
}
#define __trace_printk_check_format(fmt, args...)                       \
do {                                                                    \
        if (0)                                                          \
                ____trace_printk_check_format(fmt, ##args);             \
} while (0)

/**
 * trace_printk - printf formatting in the ftrace buffer
 * @fmt: the printf format for printing
 *
 * Note: __trace_printk is an internal function for trace_printk and
 *       the @ip is passed in via the trace_printk macro.
 *
 * This function allows a kernel developer to debug fast path sections
 * that printk is not appropriate for. By scattering in various
 * printk like tracing in the code, a developer can quickly see
 * where problems are occurring.
 *
 * This is intended as a debugging tool for the developer only.
 * Please refrain from leaving trace_printks scattered around in
 * your code. (Extra memory is used for special buffers that are
 * allocated when trace_printk() is used)
 *
 * A little optization trick is done here. If there's only one
 * argument, there's no need to scan the string for printf formats.
 * The trace_puts() will suffice. But how can we take advantage of
 * using trace_puts() when trace_printk() has only one argument?
 * By stringifying the args and checking the size we can tell
 * whether or not there are args. __stringify((__VA_ARGS__)) will
 * turn into "()\0" with a size of 3 when there are no args, anything
 * else will be bigger. All we need to do is define a string to this,
 * and then take its size and compare to 3. If it's bigger, use
 * do_trace_printk() otherwise, optimize it to trace_puts(). Then just
 * let gcc optimize the rest.
 */

#define trace_printk(fmt, ...)                          \
do {                                                    \
        char _______STR[] = __stringify((__VA_ARGS__)); \
        if (sizeof(_______STR) > 3)                     \
                do_trace_printk(fmt, ##__VA_ARGS__);    \
        else                                            \
                trace_puts(fmt);                        \
} while (0)

#define do_trace_printk(fmt, args...)                                   \
do {                                                                    \
        static const char *trace_printk_fmt                             \
                __attribute__((section("__trace_printk_fmt"))) =        \
                __builtin_constant_p(fmt) ? fmt : NULL;                 \
                                                                        \
        __trace_printk_check_format(fmt, ##args);                       \
                                                                        \
        if (__builtin_constant_p(fmt))                                  \
                __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
        else                                                            \
                __trace_printk(_THIS_IP_, fmt, ##args);                 \
} while (0)

extern __printf(2, 3)
int __trace_bprintk(unsigned long ip, const char *fmt, ...);

extern __printf(2, 3)
int __trace_printk(unsigned long ip, const char *fmt, ...);

/**
 * trace_puts - write a string into the ftrace buffer
 * @str: the string to record
 *
 * Note: __trace_bputs is an internal function for trace_puts and
 *       the @ip is passed in via the trace_puts macro.
 *
 * This is similar to trace_printk() but is made for those really fast
 * paths that a developer wants the least amount of "Heisenbug" affects,
 * where the processing of the print format is still too much.
 *
 * This function allows a kernel developer to debug fast path sections
 * that printk is not appropriate for. By scattering in various
 * printk like tracing in the code, a developer can quickly see
 * where problems are occurring.
 *
 * This is intended as a debugging tool for the developer only.
 * Please refrain from leaving trace_puts scattered around in
 * your code. (Extra memory is used for special buffers that are
 * allocated when trace_puts() is used)
 *
 * Returns: 0 if nothing was written, positive # if string was.
 *  (1 when __trace_bputs is used, strlen(str) when __trace_puts is used)
 */

#define trace_puts(str) ({                                              \
        static const char *trace_printk_fmt                             \
                __attribute__((section("__trace_printk_fmt"))) =        \
                __builtin_constant_p(str) ? str : NULL;                 \
                                                                        \
        if (__builtin_constant_p(str))                                  \
                __trace_bputs(_THIS_IP_, trace_printk_fmt);             \
        else                                                            \
                __trace_puts(_THIS_IP_, str, strlen(str));              \
})
extern int __trace_bputs(unsigned long ip, const char *str);
extern int __trace_puts(unsigned long ip, const char *str, int size);

extern void trace_dump_stack(int skip);

/*
 * The double __builtin_constant_p is because gcc will give us an error
 * if we try to allocate the static variable to fmt if it is not a
 * constant. Even with the outer if statement.
 */
#define ftrace_vprintk(fmt, vargs)                                      \
do {                                                                    \
        if (__builtin_constant_p(fmt)) {                                \
                static const char *trace_printk_fmt                     \
                  __attribute__((section("__trace_printk_fmt"))) =      \
                        __builtin_constant_p(fmt) ? fmt : NULL;         \
                                                                        \
                __ftrace_vbprintk(_THIS_IP_, trace_printk_fmt, vargs);  \
        } else                                                          \
                __ftrace_vprintk(_THIS_IP_, fmt, vargs);                \
} while (0)

extern __printf(2, 0) int
__ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap);

extern __printf(2, 0) int
__ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);

extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
#else
static inline void tracing_start(void) { }
static inline void tracing_stop(void) { }
static inline void trace_dump_stack(int skip) { }

static inline void tracing_on(void) { }
static inline void tracing_off(void) { }
static inline int tracing_is_on(void) { return 0; }
static inline void tracing_snapshot(void) { }
static inline void tracing_snapshot_alloc(void) { }

static inline __printf(1, 2)
int trace_printk(const char *fmt, ...)
{
        return 0;
}
static __printf(1, 0) inline int
ftrace_vprintk(const char *fmt, va_list ap)
{
        return 0;
}
static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
#endif /* CONFIG_TRACING */

/*
 * min()/max()/clamp() macros that also do
 * strict type-checking.. See the
 * "unnecessary" pointer comparison.
 */
#define min(x, y) ({                            \
        typeof(x) _min1 = (x);                  \
        typeof(y) _min2 = (y);                  \
        (void) (&_min1 == &_min2);              \
        _min1 < _min2 ? _min1 : _min2; })

#define max(x, y) ({                            \
        typeof(x) _max1 = (x);                  \
        typeof(y) _max2 = (y);                  \
        (void) (&_max1 == &_max2);              \
        _max1 > _max2 ? _max1 : _max2; })

#define min3(x, y, z) min((typeof(x))min(x, y), z)
#define max3(x, y, z) max((typeof(x))max(x, y), z)

/**
 * min_not_zero - return the minimum that is _not_ zero, unless both are zero
 * @x: value1
 * @y: value2
 */
#define min_not_zero(x, y) ({                   \
        typeof(x) __x = (x);                    \
        typeof(y) __y = (y);                    \
        __x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })

/**
 * clamp - return a value clamped to a given range with strict typechecking
 * @val: current value
 * @lo: lowest allowable value
 * @hi: highest allowable value
 *
 * This macro does strict typechecking of lo/hi to make sure they are of the
 * same type as val.  See the unnecessary pointer comparisons.
 */
#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)

/*
 * ..and if you can't take the strict
 * types, you can specify one yourself.
 *
 * Or not use min/max/clamp at all, of course.
 */
#define min_t(type, x, y) ({                    \
        type __min1 = (x);                      \
        type __min2 = (y);                      \
        __min1 < __min2 ? __min1: __min2; })

#define max_t(type, x, y) ({                    \
        type __max1 = (x);                      \
        type __max2 = (y);                      \
        __max1 > __max2 ? __max1: __max2; })

/**
 * clamp_t - return a value clamped to a given range using a given type
 * @type: the type of variable to use
 * @val: current value
 * @lo: minimum allowable value
 * @hi: maximum allowable value
 *
 * This macro does no typechecking and uses temporary variables of type
 * 'type' to make all the comparisons.
 */
#define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)

/**
 * clamp_val - return a value clamped to a given range using val's type
 * @val: current value
 * @lo: minimum allowable value
 * @hi: maximum allowable value
 *
 * This macro does no typechecking and uses temporary variables of whatever
 * type the input argument 'val' is.  This is useful when val is an unsigned
 * type and min and max are literals that will otherwise be assigned a signed
 * integer type.
 */
#define clamp_val(val, lo, hi) clamp_t(typeof(val), val, lo, hi)


/*
 * swap - swap value of @a and @b
 */
#define swap(a, b) \
        do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)

/**
 * container_of - cast a member of a structure out to the containing structure
 * @ptr:        the pointer to the member.
 * @type:       the type of the container struct this is embedded in.
 * @member:     the name of the member within the struct.
 *
 */
#define container_of(ptr, type, member) ({                      \
        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
        (type *)( (char *)__mptr - offsetof(type,member) );})

/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
#endif

/* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
#define VERIFY_OCTAL_PERMISSIONS(perms)                                         \
        (BUILD_BUG_ON_ZERO((perms) < 0) +                                       \
         BUILD_BUG_ON_ZERO((perms) > 0777) +                                    \
         /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */                \
         BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +       \
         BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +              \
         /* USER_WRITABLE >= GROUP_WRITABLE */                                  \
         BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +       \
         /* OTHER_WRITABLE?  Generally considered a bad idea. */                \
         BUILD_BUG_ON_ZERO((perms) & 2) +                                       \
         (perms))
#endif