Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 088/171] rbd: dont hold spinlock during messenger flush | Date | Wed, 21 Nov 2012 16:40:34 -0800 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Alex Elder <elder@dreamhost.com>
(cherry picked from commit cd9d9f5df6098c50726200d4185e9e8da32785b3)
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/block/rbd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -450,7 +450,9 @@ static void rbd_client_release(struct kr 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 kr */ 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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