From cd9d9f5df6098c50726200d4185e9e8da32785b3 Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@dreamhost.com>
Date: Wed, 4 Apr 2012 13:35:44 -0500
Subject: [PATCH] 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>
---
drivers/block/rbd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 013c7a549fb6..c1f770131654 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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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