From 51a16c1e887a5975ada27a3ae935a4f2783005da Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 17 Jun 2015 11:16:43 -0700 Subject: [PATCH] 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 Cc: Prarit Bhargava Cc: Daniel Bristot de Oliveira Cc: Richard Cochran Cc: Jan Kara Cc: Jiri Bohac Cc: Shuah Khan Cc: Ingo Molnar Link: http://lkml.kernel.org/r/1434565003-3386-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner --- tools/testing/selftests/timers/leap-a-day.c | 23 +++++++++++---------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/tools/testing/selftests/timers/leap-a-day.c b/tools/testing/selftests/timers/leap-a-day.c index 331c4f70d8a1..fb46ad6ac92c 100644 --- 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; -- 2.20.1