1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * ratelimit.c - Do something with rate limit. 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com> 6*4882a593Smuzhiyun * 7*4882a593Smuzhiyun * 2008-05-01 rewrite the function and use a ratelimit_state data struct as 8*4882a593Smuzhiyun * parameter. Now every user can use their own standalone ratelimit_state. 9*4882a593Smuzhiyun */ 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun #include <linux/ratelimit.h> 12*4882a593Smuzhiyun #include <linux/jiffies.h> 13*4882a593Smuzhiyun #include <linux/export.h> 14*4882a593Smuzhiyun 15*4882a593Smuzhiyun /* 16*4882a593Smuzhiyun * __ratelimit - rate limiting 17*4882a593Smuzhiyun * @rs: ratelimit_state data 18*4882a593Smuzhiyun * @func: name of calling function 19*4882a593Smuzhiyun * 20*4882a593Smuzhiyun * This enforces a rate limit: not more than @rs->burst callbacks 21*4882a593Smuzhiyun * in every @rs->interval 22*4882a593Smuzhiyun * 23*4882a593Smuzhiyun * RETURNS: 24*4882a593Smuzhiyun * 0 means callbacks will be suppressed. 25*4882a593Smuzhiyun * 1 means go ahead and do it. 26*4882a593Smuzhiyun */ ___ratelimit(struct ratelimit_state * rs,const char * func)27*4882a593Smuzhiyunint ___ratelimit(struct ratelimit_state *rs, const char *func) 28*4882a593Smuzhiyun { 29*4882a593Smuzhiyun /* Paired with WRITE_ONCE() in .proc_handler(). 30*4882a593Smuzhiyun * Changing two values seperately could be inconsistent 31*4882a593Smuzhiyun * and some message could be lost. (See: net_ratelimit_state). 32*4882a593Smuzhiyun */ 33*4882a593Smuzhiyun int interval = READ_ONCE(rs->interval); 34*4882a593Smuzhiyun int burst = READ_ONCE(rs->burst); 35*4882a593Smuzhiyun unsigned long flags; 36*4882a593Smuzhiyun int ret; 37*4882a593Smuzhiyun 38*4882a593Smuzhiyun if (!interval) 39*4882a593Smuzhiyun return 1; 40*4882a593Smuzhiyun 41*4882a593Smuzhiyun /* 42*4882a593Smuzhiyun * If we contend on this state's lock then almost 43*4882a593Smuzhiyun * by definition we are too busy to print a message, 44*4882a593Smuzhiyun * in addition to the one that will be printed by 45*4882a593Smuzhiyun * the entity that is holding the lock already: 46*4882a593Smuzhiyun */ 47*4882a593Smuzhiyun if (!raw_spin_trylock_irqsave(&rs->lock, flags)) 48*4882a593Smuzhiyun return 0; 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun if (!rs->begin) 51*4882a593Smuzhiyun rs->begin = jiffies; 52*4882a593Smuzhiyun 53*4882a593Smuzhiyun if (time_is_before_jiffies(rs->begin + interval)) { 54*4882a593Smuzhiyun if (rs->missed) { 55*4882a593Smuzhiyun if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) { 56*4882a593Smuzhiyun printk_deferred(KERN_WARNING 57*4882a593Smuzhiyun "%s: %d callbacks suppressed\n", 58*4882a593Smuzhiyun func, rs->missed); 59*4882a593Smuzhiyun rs->missed = 0; 60*4882a593Smuzhiyun } 61*4882a593Smuzhiyun } 62*4882a593Smuzhiyun rs->begin = jiffies; 63*4882a593Smuzhiyun rs->printed = 0; 64*4882a593Smuzhiyun } 65*4882a593Smuzhiyun if (burst && burst > rs->printed) { 66*4882a593Smuzhiyun rs->printed++; 67*4882a593Smuzhiyun ret = 1; 68*4882a593Smuzhiyun } else { 69*4882a593Smuzhiyun rs->missed++; 70*4882a593Smuzhiyun ret = 0; 71*4882a593Smuzhiyun } 72*4882a593Smuzhiyun raw_spin_unlock_irqrestore(&rs->lock, flags); 73*4882a593Smuzhiyun 74*4882a593Smuzhiyun return ret; 75*4882a593Smuzhiyun } 76*4882a593Smuzhiyun EXPORT_SYMBOL(___ratelimit); 77