3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "J. Bruce Fields" <redacted>

commit bc2df47a408f2d64cf81bcfd0f6e3e14c84cb0ab upstream.

Most frequent symptom was a BUG triggering in expire_client, with the
server locking up shortly thereafter.

Introduced by 508dc6e110c6dbdc0bbe84298ccfe22de7538486 "nfsd41:
free_session/free_client must be called under the client_lock".

Cc: Benny Halevy <redacted>
Signed-off-by: J. Bruce Fields <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfs4state.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c

@@ -862,7 +862,7 @@ static void free_session(struct kref *kr
 	struct nfsd4_session *ses;
 	int mem;
 
-	BUG_ON(!spin_is_locked(&client_lock));
+	lockdep_assert_held(&client_lock);
 	ses = container_of(kref, struct nfsd4_session, se_ref);
 	nfsd4_del_conns(ses);
 	spin_lock(&nfsd_drc_lock);

@@ -1041,7 +1041,7 @@ static struct nfs4_client *alloc_client(
 static inline void
 free_client(struct nfs4_client *clp)
 {
-	BUG_ON(!spin_is_locked(&client_lock));
+	lockdep_assert_held(&client_lock);
 	while (!list_empty(&clp->cl_sessions)) {
 		struct nfsd4_session *ses;
 		ses = list_entry(clp->cl_sessions.next, struct nfsd4_session,