From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 15 Jan 2003 03:25:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 15 Jan 2003 03:25:00 -0500 Received: from gateway-1237.mvista.com ([12.44.186.158]:47863 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id ; Wed, 15 Jan 2003 03:24:55 -0500 Message-ID: <3E248E9D.68CC1CBB@mvista.com> Date: Tue, 14 Jan 2003 14:26:37 -0800 From: george anzinger Organization: Monta Vista Software X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.18-14smp i686) X-Accept-Language: en MIME-Version: 1.0 To: "Fleischer, Julie N" CC: "'high-res-timers-discourse@lists.sourceforge.net'" , "'linux-kernel@vger.kernel.org'" Subject: Re: [BUG - HRT patch] disabling timer hangs system when multiple overruns References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org "Fleischer, Julie N" wrote: > > George - > I'm testing your 2.5.54-bk1 high-res-timers patches and am working on > debugging an issue I'm seeing where my system hangs (i.e., doesn't accept > input and I have to reboot). It happens when I'm disabling the timer by > setting the it_value to 0. I've been able to nail it down to know that it > only happens when you have generated multiple overruns (i.e., when I set up > a repeating timer and block it for > 1 timer expiry, my system then hangs > when I try to disable that timer -- I'm disabling before unblocking the > signals). > > I know "system hang" is not very descriptive. If you have input on what > types of logs I should be looking at to figure out what's really going on or > other ways I can debug, I'll do that.\ I suspect that you have run into a bug I fixed in the latest version having to do with handing off a timer from id look up to the spin lock on the timer. I was releasing the look up lock prior to taking the timer lock which allowed an interrupt to sneek in there and set up a dead lock with the interrupt code. Most likey to happen when processing overruning timers. This is fixed in the latest patch. > > I have added the tests I'm using to reproduce this issue to > http://posixtest.sf.net. The original one where I noticed it was > posixtestsuite/conformance/interfaces/timer_gettime/2-3.c after Jim > Houston's bug fix. Then, I added > posixtestsuite/conformance/interfaces/timer_settime/3-2.c and 3-3.c to help > me get to root cause. To view the issue, you can either run > timer_gettime/2-3.c, or change timer_settime/3-3.c to use a repeating timer > (in nsecs). I have included the latter below. > > ==> One related ignorant question I had is I wanted to test this against > your latest version (2.5.54-bk6), but when I went today to get the bk > patches for 2.5.54, I couldn't find them. Are those only available for the > current kernel version? That makes sense -- I should have been quicker. > But, just wanted to check if there was another way for me to get that > version. Oh, you mean the kernel.org patches, yes they are only on kernel.org until the next version. It is a rather large patch. I suppose I could send it if you can stand MB attachments. I have been off line trying to bring up my new computer on RH8.0 so I have not moved to the latest kernel as yet. -g > > Additional information is below: > kernel used = 2.5.54-bk1 > HRT patches applied = > hrtimers-core-2.5.54-bk1-1.0.patch > hrtimers-hrposix-2.5.54-bk1-1.0.patch > hrtimers-i386-2.5.54-bk1-1.0.patch > hrtimers-posix-2.5.54-bk1-1.0.patch > hrtimers-support-2.5.52-1.0.patch > > Thanks. > - Julie Fleischer > > timer_settime/3-3.c - with modifications to show issue > /* > * Copyright (c) 2002, Intel Corporation. All rights reserved. > * Created by: julie.n.fleischer REMOVE-THIS AT intel DOT com > * This file is licensed under the GPL license. For the full content > * of this license, see the COPYING file at the top level of this > * source tree. > > * Test that if value.it_value = 0, the timer is disarmed. Test by > * disarming a currently armed and blocked timer. > * > * For this test, signal SIGTOTEST will be used, clock CLOCK_REALTIME > * will be used. > */ > > #include > #include > #include > #include > #include > #include "posixtest.h" > > #define TIMEREXPIRENSEC 10000000 > #define SLEEPTIME 1 > > #define SIGTOTEST SIGALRM > > void handler(int signo) > { > printf("OK to be in once\n"); > } > > int main(int argc, char *argv[]) > { > sigset_t set; > struct sigevent ev; > struct sigaction act; > timer_t tid; > struct itimerspec its; > struct timespec ts; > > ev.sigev_notify = SIGEV_SIGNAL; > ev.sigev_signo = SIGTOTEST; > > if (sigemptyset(&set) != 0) { > perror("sigemptyset() did not return success\n"); > return PTS_UNRESOLVED; > } > > if (sigaddset(&set, SIGTOTEST) != 0) { > perror("sigaddset() did not return success\n"); > return PTS_UNRESOLVED; > } > > if (sigprocmask(SIG_SETMASK, &set, NULL) != 0) { > perror("sigprocmask() did not return success\n"); > return PTS_UNRESOLVED; > } > > if (timer_create(CLOCK_REALTIME, &ev, &tid) != 0) { > perror("timer_create() did not return success\n"); > return PTS_UNRESOLVED; > } > > /* > * First set up timer to be blocked > */ > its.it_interval.tv_sec = 0; > its.it_interval.tv_nsec = 5*TIMEREXPIRENSEC; > its.it_value.tv_sec = 0; > its.it_value.tv_nsec = TIMEREXPIRENSEC; > > printf("setup first timer\n"); > if (timer_settime(tid, 0, &its, NULL) != 0) { > perror("timer_settime() did not return success\n"); > return PTS_UNRESOLVED; > } > > printf("sleep\n"); > sleep(SLEEPTIME); > printf("awoke\n"); > > /* > * Second, set value.it_value = 0 and set up handler to catch > * signal. > */ > act.sa_handler=handler; > act.sa_flags=0; > > if (sigemptyset(&act.sa_mask) == -1) { > perror("Error calling sigemptyset\n"); > return PTS_UNRESOLVED; > } > if (sigaction(SIGTOTEST, &act, 0) == -1) { > perror("Error calling sigaction\n"); > return PTS_UNRESOLVED; > } > > its.it_interval.tv_sec = 0; > its.it_interval.tv_nsec = 0; > its.it_value.tv_sec = 0; > its.it_value.tv_nsec = 0; > > printf("setup second timer\n"); > if (timer_settime(tid, 0, &its, NULL) != 0) { > perror("timer_settime() did not return success\n"); > return PTS_UNRESOLVED; > } > > printf("unblock\n"); > if (sigprocmask(SIG_UNBLOCK, &set, NULL) != 0) { > perror("sigprocmask() did not return success\n"); > return PTS_UNRESOLVED; > } > > /* > * Ensure sleep for TIMEREXPIRE seconds not interrupted > */ > ts.tv_sec=SLEEPTIME; > ts.tv_nsec=0; > > printf("sleep again\n"); > if (nanosleep(&ts, NULL) == -1) { > printf("nanosleep() interrupted\n"); > printf("Test FAILED\n"); > return PTS_FAIL; > } > > printf("Test PASSED\n"); > return PTS_PASS; > } > > **These views are not necessarily those of my employer.** > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml