Commit cd9d9f5d authored Apr 04, 2012 by Alex Elder

rbd: don't hold spinlock during messenger flush



A recent change made changes to the rbd_client_list be protected by
a spinlock.  Unfortunately in rbd_put_client(), the lock is taken
before possibly dropping the last reference to an rbd_client, and on
the last reference that eventually calls flush_workqueue() which can
sleep.

The problem was flagged by a debug spinlock warning:
    BUG: spinlock wrong CPU on CPU#3, rbd/27814

The solution is to move the spinlock acquisition and release inside
rbd_client_release(), which is the spot where it's really needed for
protecting the removal of the rbd_client from the client list.

Signed-off-by: Alex Elder <elder@dreamhost.com>
Reviewed-by: Sage Weil <sage@newdream.net>

parent c666601a

drivers/block/rbd.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -450,7 +450,9 @@ static void rbd_client_release(struct kref *kref)
		struct rbd_client *rbdc = container_of(kref, struct rbd_client, kref);

		dout("rbd_release_client %p\n", rbdc);
		spin_lock(&rbd_client_list_lock);
		list_del(&rbdc->node);
		spin_unlock(&rbd_client_list_lock);

		ceph_destroy_client(rbdc->client);
		kfree(rbdc->rbd_opts);
		@@ -463,9 +465,7 @@ static void rbd_client_release(struct kref *kref)
		*/
		static void rbd_put_client(struct rbd_device *rbd_dev)
		{
		spin_lock(&rbd_client_list_lock);
		kref_put(&rbd_dev->rbd_client->kref, rbd_client_release);
		spin_unlock(&rbd_client_list_lock);
		rbd_dev->rbd_client = NULL;
		}

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