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/* $NetBSD: ratelimit.h,v 1.6 2022/04/09 23:44:25 riastradh Exp $ */
/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Taylor R. Campbell.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _LINUX_RATELIMIT_H_
#define _LINUX_RATELIMIT_H_
#include <sys/atomic.h>
#include <sys/stdbool.h>
#include <sys/time.h>
#define ratelimit_state linux_ratelimit_state
struct ratelimit_state {
volatile int missed;
volatile unsigned rl_lock;
struct timeval rl_lasttime;
int rl_curpps;
unsigned rl_maxpps;
};
enum {
RATELIMIT_MSG_ON_RELEASE,
};
/*
* XXX Assumes hz=100 so this works in static initializers, and/or
* hopes the caller just uses DEFAULT_RATELIMIT_INTERVAL and doesn't
* mention hz.
*/
#define DEFAULT_RATELIMIT_INTERVAL (5*100)
#define DEFAULT_RATELIMIT_BURST 10
#define DEFINE_RATELIMIT_STATE(n, i, b) \
struct ratelimit_state n = { \
.missed = 0, \
.rl_lock = 0, \
.rl_lasttime = { .tv_sec = 0, .tv_usec = 0 }, \
.rl_curpps = 0, \
.rl_maxpps = (b)/((i)/100), \
}
static inline void
ratelimit_state_init(struct ratelimit_state *r, int interval, int burst)
{
memset(r, 0, sizeof(*r));
r->rl_maxpps = burst/(interval/hz);
}
static inline void
ratelimit_set_flags(struct ratelimit_state *r, unsigned long flags)
{
}
static inline bool
__ratelimit(struct ratelimit_state *r)
{
int ok;
if (atomic_swap_uint(&r->rl_lock, 1)) {
ok = false;
goto out;
}
membar_acquire();
ok = ppsratecheck(&r->rl_lasttime, &r->rl_curpps, r->rl_maxpps);
atomic_store_release(&r->rl_lock, 0);
out: if (!ok)
atomic_store_relaxed(&r->missed, 1);
return ok;
}
#endif /* _LINUX_RATELIMIT_H_ */
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