[Cluster-devel] [PATCH] dlm: Fix spin lock already unlocked bug

[Patrick Caulfield <pcaulfie@redhat.com>]

From the "how the hell did that get in there" collection.

I just noticed this message when testing some other changes I'd made to lowcomms (to use workqueues) but the problem seems to be in
the current git trees too. I'm amazed no-one has seen it.

   BUG: spinlock already unlocked on CPU#1, dlm_recoverd/16868

Please check this before committing it someone (everyone?), in case I'm hallucinating after all the christmas punch ;-)


Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>


--- lowcomms-tcp.c	2007-01-02 13:51:40.000000000 +0000
+++ lowcomms-tcp.c.new	2007-01-02 14:01:16.000000000 +0000
@@ -709,6 +709,7 @@
 	if (!con)
 		return NULL;

+	spin_lock(&con->writequeue_lock);
 	e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
 	if ((&e->list == &con->writequeue) ||
 	    (PAGE_CACHE_SIZE - e->end < len)) {
@@ -747,6 +748,7 @@
 	struct connection *con = e->con;
 	int users;

+	spin_lock(&con->writequeue_lock);
 	users = --e->users;
 	if (users)
 		goto out;