ratelimit.h

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#ifndef _LINUX_RATELIMIT_H
#define _LINUX_RATELIMIT_H

#include <linux/param.h>
#include <linux/spinlock.h>

#define DEFAULT_RATELIMIT_INTERVAL  (5 * HZ)
#define DEFAULT_RATELIMIT_BURST     10

struct ratelimit_state {
    raw_spinlock_t  lock;       /* protect the state */

    int     interval;
    int     burst;
    int     printed;
    int     missed;
    unsigned long   begin;
};

#define DEFINE_RATELIMIT_STATE(name, interval_init, burst_init)     \
                                    \
    struct ratelimit_state name = {                 \
        .lock       = __RAW_SPIN_LOCK_UNLOCKED(name.lock),  \
        .interval   = interval_init,            \
        .burst      = burst_init,               \
    }

static inline void ratelimit_state_init(struct ratelimit_state *rs,
                    int interval, int burst)
{
    raw_spin_lock_init(&rs->lock);
    rs->interval = interval;
    rs->burst = burst;
    rs->printed = 0;
    rs->missed = 0;
    rs->begin = 0;
}

extern struct ratelimit_state printk_ratelimit_state;

extern int ___ratelimit(struct ratelimit_state *rs, const char *func);
#define __ratelimit(state) ___ratelimit(state, __func__)

#ifdef CONFIG_PRINTK

#define WARN_ON_RATELIMIT(condition, state)         \
        WARN_ON((condition) && __ratelimit(state))

#define WARN_RATELIMIT(condition, format, ...)          \
({                              \
    static DEFINE_RATELIMIT_STATE(_rs,          \
                      DEFAULT_RATELIMIT_INTERVAL,   \
                      DEFAULT_RATELIMIT_BURST); \
    int rtn = !!(condition);                \
                                \
    if (unlikely(rtn && __ratelimit(&_rs)))         \
        WARN(rtn, format, ##__VA_ARGS__);       \
                                \
    rtn;                            \
})

#else

#define WARN_ON_RATELIMIT(condition, state)         \
    WARN_ON(condition)

#define WARN_RATELIMIT(condition, format, ...)          \
({                              \
    int rtn = WARN(condition, format, ##__VA_ARGS__);   \
    rtn;                            \
})

#endif

#endif /* _LINUX_RATELIMIT_H */