From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755938AbbFQSQ7 (ORCPT ); Wed, 17 Jun 2015 14:16:59 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:36848 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753172AbbFQSQv (ORCPT ); Wed, 17 Jun 2015 14:16:51 -0400 From: John Stultz To: lkml Cc: John Stultz , Prarit Bhargava , Daniel Bristot de Oliveira , Richard Cochran , Jan Kara , Jiri Bohac , Ingo Molnar , Thomas Gleixner , Shuah Khan Subject: [PATCH] selftest: timers: Avoid signal deadlock in leap-a-day Date: Wed, 17 Jun 2015 11:16:43 -0700 Message-Id: <1434565003-3386-1-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: Prarit Bhargava Cc: Daniel Bristot de Oliveira Cc: Richard Cochran Cc: Jan Kara Cc: Jiri Bohac Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Shuah Khan Signed-off-by: John Stultz --- (This applies to tip/timers/core) 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 331c4f7..fb46ad6 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; -- 1.9.1