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Subject[BUG - HRT patch] disabling timer hangs system when multiple over runs
Date
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 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.

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 <time.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#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.**
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