From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 1/3] timer: do not spin_trylock() on UP Date: Wed, 02 Jul 2014 15:52:21 -0400 Message-ID: <20140702195231.476379359@goodmis.org> References: <20140702195220.872585955@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , stable-rt@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.228]:28983 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754452AbaGBTwd (ORCPT ); Wed, 2 Jul 2014 15:52:33 -0400 Content-Disposition: inline; filename=0001-timer-do-not-spin_trylock-on-UP.patch Sender: linux-rt-users-owner@vger.kernel.org List-ID: 3.10.44-rt46-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior This will void a warning comming from the spin-lock debugging code. The lock avoiding idea is from Steven Rostedt. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt --- kernel/timer.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/timer.c b/kernel/timer.c index 26cca8b924e7..40cfa14131ca 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1461,6 +1461,19 @@ void run_local_timers(void) * the timer softirq. */ #ifdef CONFIG_PREEMPT_RT_FULL + +#ifndef CONFIG_SMP + /* + * The spin_do_trylock() later may fail as the lock may be hold before + * the interrupt arrived. The spin-lock debugging code will raise a + * warning if the try_lock fails on UP. Since this is only an + * optimization for the FULL_NO_HZ case (not to run the timer softirq on + * an nohz_full CPU) we don't really care and shedule the softirq. + */ + raise_softirq(TIMER_SOFTIRQ); + return; +#endif + /* On RT, irq work runs from softirq */ if (irq_work_needs_cpu()) { raise_softirq(TIMER_SOFTIRQ); -- 2.0.0