diff mbox

[2/2] SUNRPC: add WARN_ON_ONCE for potential deadlock

Message ID 1351630900-6498-2-git-send-email-dros@netapp.com (mailing list archive)
State New, archived
Headers show

Commit Message

Weston Andros Adamson Oct. 30, 2012, 9:01 p.m. UTC 
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>
---
 net/sunrpc/clnt.c |    6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index cdc7564..d2737c2 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -607,6 +607,12 @@  EXPORT_SYMBOL_GPL(rpc_killall_tasks);
  */
 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);
+
 	dprintk_rcu("RPC:       shutting down %s client for %s\n",
 			clnt->cl_protname,
 			rcu_dereference(clnt->cl_xprt)->servername);