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Commit 51a16c1e authored by John Stultz's avatar John Stultz Committed by Thomas Gleixner
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selftest: Timers: Avoid signal deadlock in leap-a-day 



In 0c4a5fc9 (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: default avatarJohn 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent 906c5557

tools/testing/selftests/timers/leap-a-day.c

+12 −11
Original line number Diff line number Diff line
@@ -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;