blob: d01f4713523904b6c1da5022eb273f227b129095
1 | /* |
2 | * ratelimit.c - Do something with rate limit. |
3 | * |
4 | * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com> |
5 | * |
6 | * 2008-05-01 rewrite the function and use a ratelimit_state data struct as |
7 | * parameter. Now every user can use their own standalone ratelimit_state. |
8 | * |
9 | * This file is released under the GPLv2. |
10 | */ |
11 | |
12 | #include <linux/ratelimit.h> |
13 | #include <linux/jiffies.h> |
14 | #include <linux/export.h> |
15 | |
16 | /* |
17 | * __ratelimit - rate limiting |
18 | * @rs: ratelimit_state data |
19 | * @func: name of calling function |
20 | * |
21 | * This enforces a rate limit: not more than @rs->burst callbacks |
22 | * in every @rs->interval |
23 | * |
24 | * RETURNS: |
25 | * 0 means callbacks will be suppressed. |
26 | * 1 means go ahead and do it. |
27 | */ |
28 | int ___ratelimit(struct ratelimit_state *rs, const char *func) |
29 | { |
30 | unsigned long flags; |
31 | int ret; |
32 | |
33 | if (!rs->interval) |
34 | return 1; |
35 | |
36 | /* |
37 | * If we contend on this state's lock then almost |
38 | * by definition we are too busy to print a message, |
39 | * in addition to the one that will be printed by |
40 | * the entity that is holding the lock already: |
41 | */ |
42 | if (!raw_spin_trylock_irqsave(&rs->lock, flags)) |
43 | return 0; |
44 | |
45 | if (!rs->begin) |
46 | rs->begin = jiffies; |
47 | |
48 | if (time_is_before_jiffies(rs->begin + rs->interval)) { |
49 | if (rs->missed) { |
50 | if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) { |
51 | printk_deferred(KERN_WARNING |
52 | "%s: %d callbacks suppressed\n", |
53 | func, rs->missed); |
54 | rs->missed = 0; |
55 | } |
56 | } |
57 | rs->begin = jiffies; |
58 | rs->printed = 0; |
59 | } |
60 | if (rs->burst && rs->burst > rs->printed) { |
61 | rs->printed++; |
62 | ret = 1; |
63 | } else { |
64 | rs->missed++; |
65 | ret = 0; |
66 | } |
67 | raw_spin_unlock_irqrestore(&rs->lock, flags); |
68 | |
69 | return ret; |
70 | } |
71 | EXPORT_SYMBOL(___ratelimit); |
72 |