cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ratelimit.c (1649B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * ratelimit.c - Do something with rate limit.
      4 *
      5 * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
      6 *
      7 * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
      8 * parameter. Now every user can use their own standalone ratelimit_state.
      9 */
     10
     11#include <linux/ratelimit.h>
     12#include <linux/jiffies.h>
     13#include <linux/export.h>
     14
     15/*
     16 * __ratelimit - rate limiting
     17 * @rs: ratelimit_state data
     18 * @func: name of calling function
     19 *
     20 * This enforces a rate limit: not more than @rs->burst callbacks
     21 * in every @rs->interval
     22 *
     23 * RETURNS:
     24 * 0 means callbacks will be suppressed.
     25 * 1 means go ahead and do it.
     26 */
     27int ___ratelimit(struct ratelimit_state *rs, const char *func)
     28{
     29	unsigned long flags;
     30	int ret;
     31
     32	if (!rs->interval)
     33		return 1;
     34
     35	/*
     36	 * If we contend on this state's lock then almost
     37	 * by definition we are too busy to print a message,
     38	 * in addition to the one that will be printed by
     39	 * the entity that is holding the lock already:
     40	 */
     41	if (!raw_spin_trylock_irqsave(&rs->lock, flags))
     42		return 0;
     43
     44	if (!rs->begin)
     45		rs->begin = jiffies;
     46
     47	if (time_is_before_jiffies(rs->begin + rs->interval)) {
     48		if (rs->missed) {
     49			if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
     50				printk_deferred(KERN_WARNING
     51						"%s: %d callbacks suppressed\n",
     52						func, rs->missed);
     53				rs->missed = 0;
     54			}
     55		}
     56		rs->begin   = jiffies;
     57		rs->printed = 0;
     58	}
     59	if (rs->burst && rs->burst > rs->printed) {
     60		rs->printed++;
     61		ret = 1;
     62	} else {
     63		rs->missed++;
     64		ret = 0;
     65	}
     66	raw_spin_unlock_irqrestore(&rs->lock, flags);
     67
     68	return ret;
     69}
     70EXPORT_SYMBOL(___ratelimit);