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Merge branch 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

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Pull workqueue fix from Tejun Heo:
 "Lai's patch to fix highly unlikely but still possible workqueue stall
  during CPU hotunplug."

* 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: fix possible pool stall bug in wq_unbind_fn()
This commit is contained in:
Linus Torvalds 2013-03-18 18:47:07 -07:00
commit b63dc123b2
1 changed files with 25 additions and 19 deletions
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44
kernel/workqueue.c
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@ -3447,28 +3447,34 @@ static void wq_unbind_fn(struct work_struct *work)
spin_unlock_irq(&pool->lock);
mutex_unlock(&pool->assoc_mutex);
}
/*
* Call schedule() so that we cross rq->lock and thus can guarantee
* sched callbacks see the %WORKER_UNBOUND flag. This is necessary
* as scheduler callbacks may be invoked from other cpus.
*/
schedule();
/*
* Call schedule() so that we cross rq->lock and thus can
* guarantee sched callbacks see the %WORKER_UNBOUND flag.
* This is necessary as scheduler callbacks may be invoked
* from other cpus.
*/
schedule();
/*
* Sched callbacks are disabled now. Zap nr_running. After this,
* nr_running stays zero and need_more_worker() and keep_working()
* are always true as long as the worklist is not empty. Pools on
* @cpu now behave as unbound (in terms of concurrency management)
* pools which are served by workers tied to the CPU.
*
* On return from this function, the current worker would trigger
* unbound chain execution of pending work items if other workers
* didn't already.
*/
for_each_std_worker_pool(pool, cpu)
/*
* Sched callbacks are disabled now. Zap nr_running.
* After this, nr_running stays zero and need_more_worker()
* and keep_working() are always true as long as the
* worklist is not empty. This pool now behaves as an
* unbound (in terms of concurrency management) pool which
* are served by workers tied to the pool.
*/
atomic_set(&pool->nr_running, 0);
/*
* With concurrency management just turned off, a busy
* worker blocking could lead to lengthy stalls. Kick off
* unbound chain execution of currently pending work items.
*/
spin_lock_irq(&pool->lock);
wake_up_worker(pool);
spin_unlock_irq(&pool->lock);
}
}
/*