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Merge branch 'workqueue/for-5.16-fixes' into workqueue/for-5.17
for-5.16-fixes contains two subtle race conditions which were introduced by scheduler side code cleanups. The branch didn't get pushed out, so merge into for-5.17.
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commit
2a8ab0fbd1
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@ -864,8 +864,17 @@ void wq_worker_running(struct task_struct *task)
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if (!worker->sleeping)
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return;
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/*
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* If preempted by unbind_workers() between the WORKER_NOT_RUNNING check
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* and the nr_running increment below, we may ruin the nr_running reset
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* and leave with an unexpected pool->nr_running == 1 on the newly unbound
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* pool. Protect against such race.
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*/
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preempt_disable();
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if (!(worker->flags & WORKER_NOT_RUNNING))
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atomic_inc(&worker->pool->nr_running);
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preempt_enable();
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worker->sleeping = 0;
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}
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@ -898,6 +907,16 @@ void wq_worker_sleeping(struct task_struct *task)
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worker->sleeping = 1;
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raw_spin_lock_irq(&pool->lock);
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/*
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* Recheck in case unbind_workers() preempted us. We don't
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* want to decrement nr_running after the worker is unbound
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* and nr_running has been reset.
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*/
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if (worker->flags & WORKER_NOT_RUNNING) {
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raw_spin_unlock_irq(&pool->lock);
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return;
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}
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/*
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* The counterpart of the following dec_and_test, implied mb,
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* worklist not empty test sequence is in insert_work().
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@ -1526,7 +1545,8 @@ static void __queue_work(int cpu, struct workqueue_struct *wq,
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* @work: work to queue
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*
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* We queue the work to a specific CPU, the caller must ensure it
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* can't go away.
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* can't go away. Callers that fail to ensure that the specified
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* CPU cannot go away will execute on a randomly chosen CPU.
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*
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* Return: %false if @work was already on a queue, %true otherwise.
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*/
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