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selftest: Timers: Avoid signal deadlock in leap-a-day

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In 0c4a5fc95b (Add leap-second timer edge testing to
leap-a-day.c), we added a timer to the test which checks to make
sure timers near the leapsecond edge behave correctly.

However, the output generated from the timer uses ctime_r, which
isn't async-signal safe, and should that signal land while the
main test is using ctime_r to print its output, its possible for
the test to deadlock on glibc internal locks.

Thus this patch reworks the output to avoid using ctime_r in
the signal handler.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1434565003-3386-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
John Stultz 2015-06-17 11:16:43 -07:00 committed by Thomas Gleixner
parent 906c55579a
commit 51a16c1e88
1 changed files with 12 additions and 11 deletions
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23
tools/testing/selftests/timers/leap-a-day.c
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@ -141,27 +141,28 @@ void handler(int unused)
void sigalarm(int signo)
{
struct timex tx;
char buf[26];
int ret;
tx.modes = 0;
ret = adjtimex(&tx);
ctime_r(&tx.time.tv_sec, buf);
buf[strlen(buf)-1] = 0; /*remove trailing\n */
printf("%s + %6ld us (%i)\t%s - TIMER FIRED\n",
buf,
if (tx.time.tv_sec < next_leap) {
printf("Error: Early timer expiration! (Should be %ld)\n", next_leap);
error_found = 1;
printf("adjtimex: %10ld sec + %6ld us (%i)\t%s\n",
tx.time.tv_sec,
tx.time.tv_usec,
tx.tai,
time_state_str(ret));
if (tx.time.tv_sec < next_leap) {
printf("Error: Early timer expiration!\n");
error_found = 1;
}
if (ret != TIME_WAIT) {
printf("Error: Incorrect NTP state?\n");
printf("Error: Timer seeing incorrect NTP state? (Should be TIME_WAIT)\n");
error_found = 1;
printf("adjtimex: %10ld sec + %6ld us (%i)\t%s\n",
tx.time.tv_sec,
tx.time.tv_usec,
tx.tai,
time_state_str(ret));
}
}
@ -297,7 +298,7 @@ int main(int argc, char **argv)
printf("Scheduling leap second for %s", ctime(&next_leap));
/* Set up timer */
printf("Setting timer for %s", ctime(&next_leap));
printf("Setting timer for %ld - %s", next_leap, ctime(&next_leap));
memset(&se, 0, sizeof(se));
se.sigev_notify = SIGEV_SIGNAL;
se.sigev_signo = signum;