From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [PATCH RT 02/13] preempt-lazy: Add the lazy-preemption check to preempt_schedule() Date: Wed, 02 Mar 2016 10:48:49 -0500 Message-ID: <20160302154903.401555798@goodmis.org> References: <20160302154847.937325532@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Mike Galbraith To: linux-kernel@vger.kernel.org, linux-rt-users Return-path: Content-Disposition: inline; filename=0002-preempt-lazy-Add-the-lazy-preemption-check-to-preemp.patch Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org 3.12.54-rt74-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior Probably in the rebase onto v4.1 this check got moved into less commonly used preempt_schedule_notrace(). This patch ensures that both functions use it. Reported-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt --- kernel/sched/core.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 14b5ba66fa72..a936937c3535 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2728,6 +2728,30 @@ void __sched schedule_preempt_disabled(void) preempt_disable(); } +#ifdef CONFIG_PREEMPT_LAZY +/* + * If TIF_NEED_RESCHED is then we allow to be scheduled away since this is + * set by a RT task. Oterwise we try to avoid beeing scheduled out as long as + * preempt_lazy_count counter >0. + */ +static int preemptible_lazy(void) +{ + if (test_thread_flag(TIF_NEED_RESCHED)) + return 1; + if (current_thread_info()->preempt_lazy_count) + return 0; + return 1; +} + +#else + +static int preemptible_lazy(void) +{ + return 1; +} + +#endif + #ifdef CONFIG_PREEMPT /* * this is the entry point to schedule() from in-kernel preemption @@ -2742,15 +2766,9 @@ asmlinkage void __sched notrace preempt_schedule(void) */ if (likely(!preemptible())) return; - -#ifdef CONFIG_PREEMPT_LAZY - /* - * Check for lazy preemption - */ - if (current_thread_info()->preempt_lazy_count && - !test_thread_flag(TIF_NEED_RESCHED)) + if (!preemptible_lazy()) return; -#endif + do { add_preempt_count_notrace(PREEMPT_ACTIVE); /* -- 2.7.0