From f4e97b682ac92d2aed3db68f396b022113d9ad30 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 22 Jun 2011 19:47:01 +0200 Subject: [PATCH] sched: Move blk_schedule_flush_plug() out of __schedule() commit 9c40cef2b799f9b5e7fa5de4d2ad3a0168ba118c upstream. There is no real reason to run blk_schedule_flush_plug() with interrupts and preemption disabled. Move it into schedule() and call it when the task is going voluntarily to sleep. There might be false positives when the task is woken between that call and actually scheduling, but that's not really different from being woken immediately after switching away. This fixes a deadlock in the scheduler where the blk_schedule_flush_plug() callchain enables interrupts and thereby allows a wakeup to happen of the task that's going to sleep. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra Cc: Tejun Heo Cc: Jens Axboe Cc: Linus Torvalds Link: http://lkml.kernel.org/n/tip-dwfxtra7yg1b5r65m32ywtct@git.kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 64f93d18e4d4..ce2a3406ec01 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4285,16 +4285,6 @@ need_resched: if (to_wakeup) try_to_wake_up_local(to_wakeup); } - - /* - * If we are going to sleep and we have plugged IO - * queued, make sure to submit it to avoid deadlocks. - */ - if (blk_needs_flush_plug(prev)) { - raw_spin_unlock(&rq->lock); - blk_schedule_flush_plug(prev); - raw_spin_lock(&rq->lock); - } } switch_count = &prev->nvcsw; } @@ -4333,8 +4323,23 @@ need_resched: goto need_resched; } +static inline void sched_submit_work(struct task_struct *tsk) +{ + if (!tsk->state) + return; + /* + * If we are going to sleep and we have plugged IO queued, + * make sure to submit it to avoid deadlocks. + */ + if (blk_needs_flush_plug(tsk)) + blk_schedule_flush_plug(tsk); +} + asmlinkage void schedule(void) { + struct task_struct *tsk = current; + + sched_submit_work(tsk); __schedule(); } EXPORT_SYMBOL(schedule); -- 2.34.1