3.18.27-rt27-rc1 stable review patch. If anyone has any objections, please let me know.
------------------ From: Sebastian Andrzej Siewior <[email protected]> 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 <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> --- 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 9e01a8f358f8..8214206817f2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3164,6 +3164,30 @@ 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 @@ -3178,15 +3202,9 @@ asmlinkage __visible 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 { __preempt_count_add(PREEMPT_ACTIVE); /* -- 2.7.0
