1 /* $NetBSD: ratelimit.h,v 1.6 2022/04/09 23:44:25 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Taylor R. Campbell. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #ifndef _LINUX_RATELIMIT_H_ 33 #define _LINUX_RATELIMIT_H_ 34 35 #include <sys/atomic.h> 36 #include <sys/stdbool.h> 37 #include <sys/time.h> 38 39 #define ratelimit_state linux_ratelimit_state 40 41 struct ratelimit_state { 42 volatile int missed; 43 44 volatile unsigned rl_lock; 45 struct timeval rl_lasttime; 46 int rl_curpps; 47 unsigned rl_maxpps; 48 }; 49 50 enum { 51 RATELIMIT_MSG_ON_RELEASE, 52 }; 53 54 /* 55 * XXX Assumes hz=100 so this works in static initializers, and/or 56 * hopes the caller just uses DEFAULT_RATELIMIT_INTERVAL and doesn't 57 * mention hz. 58 */ 59 #define DEFAULT_RATELIMIT_INTERVAL (5*100) 60 #define DEFAULT_RATELIMIT_BURST 10 61 62 #define DEFINE_RATELIMIT_STATE(n, i, b) \ 63 struct ratelimit_state n = { \ 64 .missed = 0, \ 65 .rl_lock = 0, \ 66 .rl_lasttime = { .tv_sec = 0, .tv_usec = 0 }, \ 67 .rl_curpps = 0, \ 68 .rl_maxpps = (b)/((i)/100), \ 69 } 70 71 static inline void 72 ratelimit_state_init(struct ratelimit_state *r, int interval, int burst) 73 { 74 75 memset(r, 0, sizeof(*r)); 76 r->rl_maxpps = burst/(interval/hz); 77 } 78 79 static inline void 80 ratelimit_set_flags(struct ratelimit_state *r, unsigned long flags) 81 { 82 } 83 84 static inline bool 85 __ratelimit(struct ratelimit_state *r) 86 { 87 int ok; 88 89 if (atomic_swap_uint(&r->rl_lock, 1)) { 90 ok = false; 91 goto out; 92 } 93 membar_acquire(); 94 ok = ppsratecheck(&r->rl_lasttime, &r->rl_curpps, r->rl_maxpps); 95 atomic_store_release(&r->rl_lock, 0); 96 97 out: if (!ok) 98 atomic_store_relaxed(&r->missed, 1); 99 return ok; 100 } 101 102 #endif /* _LINUX_RATELIMIT_H_ */ 103