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authorLinus Torvalds <torvalds@linux-foundation.org>2013-03-18 18:47:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-18 18:47:07 -0700
commitb63dc123b20e54a306ff1bfa191e511c506ee331 (patch)
treeab7b2b9259bbb1bf9c139e71b94cdfd27c69a9f8 /kernel
parent35f8c769aa5f3d9a81d50e9bdcbfd4151e72a0c9 (diff)
parenteb2834285cf172856cd12f66892fc7467935ebed (diff)
Merge branch 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
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()
Diffstat (limited to 'kernel')
-rw-r--r--kernel/workqueue.c44
1 files changed, 25 insertions, 19 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 55fac5b991b7..b48cd597145d 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -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);
+ }
}
/*