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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106// SPDX-License-Identifier: GPL-2.0-only/* * ratelimit.c - Do something with rate limit. * * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com> * * 2008-05-01 rewrite the function and use a ratelimit_state data struct as * parameter. Now every user can use their own standalone ratelimit_state. */
#include <linux/ratelimit.h>#include <linux/jiffies.h>#include <linux/export.h>
/* * __ratelimit - rate limiting * @rs: ratelimit_state data * @func: name of calling function * * This enforces a rate limit: not more than @rs->burst callbacks * in every @rs->interval * * RETURNS: * 0 means callbacks will be suppressed. * 1 means go ahead and do it. */int ___ratelimit(struct ratelimit_state *rs, const char *func){ /* Paired with WRITE_ONCE() in .proc_handler(). * Changing two values separately could be inconsistent * and some message could be lost. (See: net_ratelimit_state). */ int interval = READ_ONCE(rs->interval); int burst = READ_ONCE(rs->burst); unsigned long flags; int ret = 0;
/* * Zero interval says never limit, otherwise, non-positive burst * says always limit. */ if (interval <= 0 || burst <= 0) { WARN_ONCE(interval < 0 || burst < 0, "Negative interval (%d) or burst (%d): Uninitialized ratelimit_state structure?\n", interval, burst); ret = interval == 0 || burst > 0; if (!(READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED) || (!interval && !burst) || !raw_spin_trylock_irqsave(&rs->lock, flags)) goto nolock_ret;
/* Force re-initialization once re-enabled. */ rs->flags &= ~RATELIMIT_INITIALIZED; goto unlock_ret; }
/* * If we contend on this state's lock then just check if * the current burst is used or not. It might cause * false positive when we are past the interval and * the current lock owner is just about to reset it. */ if (!raw_spin_trylock_irqsave(&rs->lock, flags)) { if (READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED && atomic_read(&rs->rs_n_left) > 0 && atomic_dec_return(&rs->rs_n_left) >= 0) ret = 1; goto nolock_ret; }
if (!(rs->flags & RATELIMIT_INITIALIZED)) { rs->begin = jiffies; rs->flags |= RATELIMIT_INITIALIZED; atomic_set(&rs->rs_n_left, rs->burst); }
if (time_is_before_jiffies(rs->begin + interval)) { int m;
/* * Reset rs_n_left ASAP to reduce false positives * in parallel calls, see above. */ atomic_set(&rs->rs_n_left, rs->burst); rs->begin = jiffies;
if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) { m = ratelimit_state_reset_miss(rs); if (m) { printk_deferred(KERN_WARNING "%s: %d callbacks suppressed\n", func, m); } } }
/* Note that the burst might be taken by a parallel call. */ if (atomic_read(&rs->rs_n_left) > 0 && atomic_dec_return(&rs->rs_n_left) >= 0) ret = 1;
unlock_ret: raw_spin_unlock_irqrestore(&rs->lock, flags);
nolock_ret: if (!ret) ratelimit_state_inc_miss(rs);
return ret;}EXPORT_SYMBOL(___ratelimit);