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File: [cvs.NetBSD.org] / src / sys / kern / kern_rate.c (download)

Revision 1.2, Wed Dec 12 11:10:56 2012 UTC (11 years, 3 months ago) by pooka
Branch: MAIN
CVS Tags: yamt-pagecache-base9, yamt-pagecache-base8, yamt-pagecache-base7, tls-maxphys-base-20171202, tls-maxphys-base, tls-earlyentropy-base, tls-earlyentropy, thorpej-ifq-base, thorpej-ifq, thorpej-i2c-spi-conf2-base, thorpej-i2c-spi-conf2, thorpej-i2c-spi-conf-base, thorpej-i2c-spi-conf, thorpej-futex2-base, thorpej-futex2, thorpej-futex-base, thorpej-futex, thorpej-cfargs2-base, thorpej-cfargs2, thorpej-cfargs-base, thorpej-cfargs, thorpej-altq-separation-base, thorpej-altq-separation, rmind-smpnet-nbase, rmind-smpnet-base, rmind-smpnet, riastradh-xf86-video-intel-2-7-1-pre-2-21-15, riastradh-drm2-base3, riastradh-drm2-base2, riastradh-drm2-base1, riastradh-drm2-base, riastradh-drm2, prg-localcount2-base3, prg-localcount2-base2, prg-localcount2-base1, prg-localcount2-base, prg-localcount2, phil-wifi-base, phil-wifi-20200421, phil-wifi-20200411, phil-wifi-20200406, phil-wifi-20191119, phil-wifi-20190609, phil-wifi, pgoyette-localcount-base, pgoyette-localcount-20170426, pgoyette-localcount-20170320, pgoyette-localcount-20170107, pgoyette-localcount-20161104, pgoyette-localcount-20160806, pgoyette-localcount-20160726, pgoyette-localcount, pgoyette-compat-merge-20190127, pgoyette-compat-base, pgoyette-compat-20190127, pgoyette-compat-20190118, pgoyette-compat-1226, pgoyette-compat-1126, pgoyette-compat-1020, pgoyette-compat-0930, pgoyette-compat-0906, pgoyette-compat-0728, pgoyette-compat-0625, pgoyette-compat-0521, pgoyette-compat-0502, pgoyette-compat-0422, pgoyette-compat-0415, pgoyette-compat-0407, pgoyette-compat-0330, pgoyette-compat-0322, pgoyette-compat-0315, pgoyette-compat, perseant-stdc-iso10646-base, perseant-stdc-iso10646, nick-nhusb-base-20170825, nick-nhusb-base-20170204, nick-nhusb-base-20161204, nick-nhusb-base-20161004, nick-nhusb-base-20160907, nick-nhusb-base-20160529, nick-nhusb-base-20160422, nick-nhusb-base-20160319, nick-nhusb-base-20151226, nick-nhusb-base-20150921, nick-nhusb-base-20150606, nick-nhusb-base-20150406, nick-nhusb-base, nick-nhusb, netbsd-9-base, netbsd-9-3-RELEASE, netbsd-9-2-RELEASE, netbsd-9-1-RELEASE, netbsd-9-0-RELEASE, netbsd-9-0-RC2, netbsd-9-0-RC1, netbsd-9, netbsd-8-base, netbsd-8-2-RELEASE, netbsd-8-1-RELEASE, netbsd-8-1-RC1, netbsd-8-0-RELEASE, netbsd-8-0-RC2, netbsd-8-0-RC1, netbsd-8, netbsd-7-nhusb-base-20170116, netbsd-7-nhusb-base, netbsd-7-nhusb, netbsd-7-base, netbsd-7-2-RELEASE, netbsd-7-1-RELEASE, netbsd-7-1-RC2, netbsd-7-1-RC1, netbsd-7-1-2-RELEASE, netbsd-7-1-1-RELEASE, netbsd-7-1, netbsd-7-0-RELEASE, netbsd-7-0-RC3, netbsd-7-0-RC2, netbsd-7-0-RC1, netbsd-7-0-2-RELEASE, netbsd-7-0-1-RELEASE, netbsd-7-0, netbsd-7, netbsd-10-base, netbsd-10-0-RC6, netbsd-10-0-RC5, netbsd-10-0-RC4, netbsd-10-0-RC3, netbsd-10-0-RC2, netbsd-10-0-RC1, netbsd-10, matt-nb8-mediatek-base, matt-nb8-mediatek, localcount-20160914, khorben-n900, jdolecek-ncq-base, jdolecek-ncq, isaki-audio2-base, isaki-audio2, is-mlppp-base, is-mlppp, cjep_sun2x-base1, cjep_sun2x-base, cjep_sun2x, cjep_staticlib_x-base1, cjep_staticlib_x-base, cjep_staticlib_x, bouyer-xenpvh-base2, bouyer-xenpvh-base1, bouyer-xenpvh-base, bouyer-xenpvh, bouyer-sunxi-drm-base, bouyer-sunxi-drm, bouyer-socketcan-base1, bouyer-socketcan-base, bouyer-socketcan, agc-symver-base, agc-symver, ad-namecache-base3, ad-namecache-base2, ad-namecache-base1, ad-namecache-base, ad-namecache, HEAD
Changes since 1.1: +3 -3 lines

Signed overflow is undefined behavior, and one version of gcc
clearly tells us:

	kern_rate.c:98: warning: assuming signed overflow does not
	occur when assuming that (X + c) > X is always true

Check value against INT_MAX instead.  Also, for good measure throw
in a __predict() to flag the assumed common case.

/*	$NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $	*/

/*-
 * Copyright (c) 2000, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christopher G. Demetriou.
 *
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $");

#include <sys/param.h>
#include <sys/time.h>

/*
 * ratecheck(): simple time-based rate-limit checking.  see ratecheck(9)
 * for usage and rationale.
 */
int
ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
{
	struct timeval tv, delta;
	int rv = 0;

	getmicrouptime(&tv);
	timersub(&tv, lasttime, &delta);

	/*
	 * check for 0,0 is so that the message will be seen at least once,
	 * even if interval is huge.
	 */
	if (timercmp(&delta, mininterval, >=) ||
	    (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
		*lasttime = tv;
		rv = 1;
	}

	return (rv);
}

/*
 * ppsratecheck(): packets (or events) per second limitation.
 */
int
ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
{
	struct timeval tv, delta;
	int rv;

	getmicrouptime(&tv);
	timersub(&tv, lasttime, &delta);

	/*
	 * check for 0,0 is so that the message will be seen at least once.
	 * if more than one second have passed since the last update of
	 * lasttime, reset the counter.
	 *
	 * we do increment *curpps even in *curpps < maxpps case, as some may
	 * try to use *curpps for stat purposes as well.
	 */
	if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
	    delta.tv_sec >= 1) {
		*lasttime = tv;
		*curpps = 0;
	}
	if (maxpps < 0)
		rv = 1;
	else if (*curpps < maxpps)
		rv = 1;
	else
		rv = 0;

#if 1 /*DIAGNOSTIC?*/
	/* be careful about wrap-around */
	if (__predict_true(*curpps != INT_MAX))
		*curpps = *curpps + 1;
#else
	/*
	 * assume that there's not too many calls to this function.
	 * not sure if the assumption holds, as it depends on *caller's*
	 * behavior, not the behavior of this function.
	 * IMHO it is wrong to make assumption on the caller's behavior,
	 * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
	 */
	*curpps = *curpps + 1;
#endif

	return (rv);
}