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); 71