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/module.h> 15 16 /* 17 * __ratelimit - rate limiting 18 * @rs: ratelimit_state data 19 * 20 * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks 21 * in every @rs->ratelimit_jiffies 22 */ 23 int ___ratelimit(struct ratelimit_state *rs, const char *func) 24 { 25 unsigned long flags; 26 int ret; 27 28 if (!rs->interval) 29 return 1; 30 31 /* 32 * If we contend on this state's lock then almost 33 * by definition we are too busy to print a message, 34 * in addition to the one that will be printed by 35 * the entity that is holding the lock already: 36 */ 37 if (!spin_trylock_irqsave(&rs->lock, flags)) 38 return 1; 39 40 if (!rs->begin) 41 rs->begin = jiffies; 42 43 if (time_is_before_jiffies(rs->begin + rs->interval)) { 44 if (rs->missed) 45 printk(KERN_WARNING "%s: %d callbacks suppressed\n", 46 func, rs->missed); 47 rs->begin = 0; 48 rs->printed = 0; 49 rs->missed = 0; 50 } 51 if (rs->burst && rs->burst > rs->printed) { 52 rs->printed++; 53 ret = 1; 54 } else { 55 rs->missed++; 56 ret = 0; 57 } 58 spin_unlock_irqrestore(&rs->lock, flags); 59 60 return ret; 61 } 62 EXPORT_SYMBOL(___ratelimit); 63