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

In 0c4a5fc95b1df (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>

diff --git a/tools/testing/selftests/timers/leap-a-day.c b/tools/testing/selftests/timers/leap-a-day.c
index 331c4f7..fb46ad6 100644 (file)
--- a/tools/testing/selftests/timers/leap-a-day.c
+++ b/tools/testing/selftests/timers/leap-a-day.c
@@ -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;