| 1 | |
| 2 | |
| 3 | * ratelimit.c - Do something with rate limit.
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| 4 | *
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| 5 | * Isolated from kernel/printk.c by Dave Young <[email protected]>
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| 6 | *
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| 7 | * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
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| 8 | * parameter. Now every user can use their own standalone ratelimit_state.
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| 9 |
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| 10 |
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| 11 | #include <linux/ratelimit.h>
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| 12 | #include <linux/jiffies.h>
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| 13 | #include <linux/export.h>
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| 14 |
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| 15 | |
| 16 | * __ratelimit - rate limiting
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| 17 | * @rs: ratelimit_state data
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| 18 | * @func: name of calling function
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| 19 | *
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| 20 | * This enforces a rate limit: not more than @rs->burst callbacks
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| 21 | * in every @rs->interval
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| 22 | *
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| 23 | * RETURNS:
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| 24 | * 0 means callbacks will be suppressed.
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| 25 | * 1 means go ahead and do it.
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| 26 |
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| 27 | int ___ratelimit(struct ratelimit_state *rs, const char *func)
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| 28 | {
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| 29 | unsigned long flags;
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| 30 | int ret;
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| 31 |
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| 32 | if (!rs->interval)
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| 33 | return 1;
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| 34 |
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| 35 | |
| 36 | * If we contend on this state's lock then almost
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| 37 | * by definition we are too busy to print a message,
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| 38 | * in addition to the one that will be printed by
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| 39 | * the entity that is holding the lock already:
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| 40 |
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| 41 | if (!raw_spin_trylock_irqsave(&rs->lock, flags))
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| 42 | return 0;
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| 43 |
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| 44 | if (!rs->begin)
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| 45 | rs->begin = jiffies;
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| 46 |
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| 47 | if (time_is_before_jiffies(rs->begin + rs->interval)) {
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| 48 | if (rs->missed) {
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| 49 | if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
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| 50 | printk_deferred(KERN_WARNING
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| 51 | "%s: %d callbacks suppressed\n",
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| 52 | func, rs->missed);
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| 53 | rs->missed = 0;
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| 54 | }
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| 55 | }
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| 56 | rs->begin = jiffies;
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| 57 | rs->printed = 0;
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| 58 | }
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| 59 | if (rs->burst && rs->burst > rs->printed) {
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| 60 | rs->printed++;
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| 61 | ret = 1;
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| 62 | } else {
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| 63 | rs->missed++;
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| 64 | ret = 0;
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| 65 | }
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| 66 | raw_spin_unlock_irqrestore(&rs->lock, flags);
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| 67 |
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| 68 | return ret;
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| 69 | }
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| 70 | EXPORT_SYMBOL(___ratelimit);
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