Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
[platform/kernel/linux-rpi.git] / lib / ratelimit.c
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  */
27 int ___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 }
70 EXPORT_SYMBOL(___ratelimit);