mirror of
https://github.com/torvalds/linux.git
synced 2024-12-21 10:31:54 +00:00
6bae8ceb90
While reading rs->interval and rs->burst, they can be changed
concurrently via sysctl (e.g. net_ratelimit_state). Thus, we
need to add READ_ONCE() to their readers.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
// 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 seperately 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;
|
|
|
|
if (!interval)
|
|
return 1;
|
|
|
|
/*
|
|
* If we contend on this state's lock then almost
|
|
* by definition we are too busy to print a message,
|
|
* in addition to the one that will be printed by
|
|
* the entity that is holding the lock already:
|
|
*/
|
|
if (!raw_spin_trylock_irqsave(&rs->lock, flags))
|
|
return 0;
|
|
|
|
if (!rs->begin)
|
|
rs->begin = jiffies;
|
|
|
|
if (time_is_before_jiffies(rs->begin + interval)) {
|
|
if (rs->missed) {
|
|
if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
|
|
printk_deferred(KERN_WARNING
|
|
"%s: %d callbacks suppressed\n",
|
|
func, rs->missed);
|
|
rs->missed = 0;
|
|
}
|
|
}
|
|
rs->begin = jiffies;
|
|
rs->printed = 0;
|
|
}
|
|
if (burst && burst > rs->printed) {
|
|
rs->printed++;
|
|
ret = 1;
|
|
} else {
|
|
rs->missed++;
|
|
ret = 0;
|
|
}
|
|
raw_spin_unlock_irqrestore(&rs->lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(___ratelimit);
|