SUNRPC: add WARN_ON_ONCE for potential deadlock
rpc_shutdown_client should never be called from a workqueue context.
If it is, it could deadlock looping forever trying to kill tasks that are
assigned to the same kworker thread (and will never run rpc_exit_task).
Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index cdc7564b..dd2532c 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -607,6 +607,13 @@
*/
void rpc_shutdown_client(struct rpc_clnt *clnt)
{
+ /*
+ * To avoid deadlock, never call rpc_shutdown_client from a
+ * workqueue context!
+ */
+ WARN_ON_ONCE(current->flags & PF_WQ_WORKER);
+ might_sleep();
+
dprintk_rcu("RPC: shutting down %s client for %s\n",
clnt->cl_protname,
rcu_dereference(clnt->cl_xprt)->servername);