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authorPeter Zijlstra <peterz@infradead.org>2021-06-11 10:28:11 +0200
committerPeter Zijlstra <peterz@infradead.org>2021-06-18 11:43:06 +0200
commit37aadc687ab441bbcb693ddae613acf9afcea1ab (patch)
tree83a8142d60076d6742205e513fc0fac6c0435fa5 /kernel/softirq.c
parentb2c0931a07b7376c6291e0cfb347ad27f7b66263 (diff)
sched: Unbreak wakeups
Remove broken task->state references and let wake_up_process() DTRT. The anti-pattern in these patches breaks the ordering of ->state vs COND as described in the comment near set_current_state() and can lead to missed wakeups: (OoO load, observes RUNNING)<-. for (;;) { | t->state = UNINTERRUPTIBLE; | smp_mb(); ,-----> | (observes !COND) | / if (COND) ---------' | COND = 1; break; `- if (t->state != RUNNING) wake_up_process(t); // not done schedule(); // forever waiting } t->state = TASK_RUNNING; Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210611082838.160855222@infradead.org
Diffstat (limited to 'kernel/softirq.c')
-rw-r--r--kernel/softirq.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 4992853ef53d..5ddc3b15a4db 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -76,7 +76,7 @@ static void wakeup_softirqd(void)
/* Interrupts are disabled: no need to stop preemption */
struct task_struct *tsk = __this_cpu_read(ksoftirqd);
- if (tsk && tsk->state != TASK_RUNNING)
+ if (tsk)
wake_up_process(tsk);
}