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
ratelimit_state_init(struct ratelimit_state * r,int interval,int burst)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
ratelimit_set_flags(struct ratelimit_state * r,unsigned long flags)80 ratelimit_set_flags(struct ratelimit_state *r, unsigned long flags)
81 {
82 }
83
84 static inline bool
__ratelimit(struct ratelimit_state * r)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