From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752488AbeDIMYS (ORCPT ); Mon, 9 Apr 2018 08:24:18 -0400 Received: from mout.kundenserver.de ([212.227.126.130]:46315 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752339AbeDIMYQ (ORCPT ); Mon, 9 Apr 2018 08:24:16 -0400 From: Arnd Bergmann To: Frederic Weisbecker , Thomas Gleixner , Ingo Molnar Cc: Arnd Bergmann , Peter Zijlstra , "Rafael J. Wysocki" , "Paul E. McKenney" , linux-kernel@vger.kernel.org Subject: [PATCH] tick-sched: avoid a maybe-uninitialized warning Date: Mon, 9 Apr 2018 14:23:33 +0200 Message-Id: <20180409122339.1709840-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K1:UnUjYs4VVfULcW1CA3PwUiPKZ5HXk8zJXRTyX2UV7MPGA9qGoPq PCX2mqF16f04Lm5xi0GAgPm6O7r2YGmIq+cyADGJE8FQ6ZaXAjp1Ez30ZLJqqnesSeLnU+P dDjb4W4VVm68Md5r6KCN9beM5QANXpGHHZ970Nf7C2e8ku4TYqoeRFzoam0IXD90C9MG5ig PQTfd8JyaKzbPUFeFxYwA== X-UI-Out-Filterresults: notjunk:1;V01:K0:iOWimIA0ojc=:ITd5rM/1PwDbaoUTS07ZWH gBU3u6kTrHmu91hMWBjFYhEMrlgTvzxtvjZh2//cVsv8nnDfgnn0pl8xxe4MkcWhCFdPaF1AL RTDbEmCTHduC6sBT8uInC80av+hSy6cH3IbiENMDG4L8BSYJd3nlfrKtbC/iK5X/O8W2XOQ0X Nhke+lsGMJGhNBvvoQL5IaFILPIdtpWSdyLuEUKVGn9yz8+5MvHp8T8I4WFtrINwBBDSxCsaw PjxldlBNH7dVGh0q/AHSiSqm7njQypGQTrG2arLwqHV586GDhkX2b9DFdPhrN7MzLGVcLcvef CZxKKKeYbL2H7OJgV68xPP4CAiWVQ/tZKq2RaphFtQBneaqq71Nx8SeaEnThUih5fr363v1/E ++6yalLlV3P4YqMRBqrVikFcDUYpPQ7kKTtEQrFGuFMUN4W2LWetgl2hychp8wZ+bEEsalXZy DTZXbwwh8CDYAIkuk2/oX37Coego0eZE0iBbnn1aWHBUAc0HnU7gVpaYGlRhmhyP0cxLZoseH X20+PalB+PsMs3RjGdAkllJZSxgxYS5BFAotMenFSJCv5FD7pLeSH3Ug8jy+QdCwfx9LJOPMR HPsc3bp68k2uqVUdXC6KODm7gSFia8iWjnQumrFgc6LnJ/rd8ZOLJ37yvdtgogEvFTu5gbimc oyq1uA30lkX5W1ebRt4srRcF9U54VDpeayJOk0XCBxZUL/mVTKwUy7LfqFYhP+3gTU5RRagrx lIhvxgpxuQIFTEXtAlqBlzn19788FGzCcp3HiA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The use of bitfields seems to confuse gcc, leading to a false-positive warning in all compiler versions: kernel/time/tick-sched.c: In function 'tick_nohz_idle_exit': kernel/time/tick-sched.c:538:2: error: 'now' may be used uninitialized in this function [-Werror=maybe-uninitialized] This introduces a temporary variable to track the flags so gcc doesn't have to evaluate twice, eliminating the code path that leads to the warning. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85301 Fixes: 1cae544d42d2 ("nohz: Gather tick_sched booleans under a common flag field") Signed-off-by: Arnd Bergmann --- kernel/time/tick-sched.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 7eef9431ca24..646645e981f9 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1143,6 +1143,7 @@ void tick_nohz_idle_restart_tick(void) void tick_nohz_idle_exit(void) { struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + bool idle_active, tick_stopped; ktime_t now; local_irq_disable(); @@ -1151,14 +1152,16 @@ void tick_nohz_idle_exit(void) WARN_ON_ONCE(ts->timer_expires_base); ts->inidle = 0; + idle_active = ts->idle_active; + tick_stopped = ts->tick_stopped; - if (ts->idle_active || ts->tick_stopped) + if (idle_active || tick_stopped) now = ktime_get(); - if (ts->idle_active) + if (idle_active) tick_nohz_stop_idle(ts, now); - if (ts->tick_stopped) + if (tick_stopped) __tick_nohz_idle_restart_tick(ts, now); local_irq_enable(); -- 2.9.0