[PATCH] nfs: Fix an Oops in the RPC debug code...

From: Trond Myklebust <trond.myklebust@fys.uio.no>

Enabling rpc_debug can currently result in an Oops due to an incorrect
pointer check.

include/linux/sunrpc/sched.h

@@ -205,7 +205,7 @@ rpc_exit(struct rpc_task *task, int status)
 static __inline__ char *
 rpc_qname(struct rpc_wait_queue *q)
 {
-	return q->name? q->name : "unknown";
+	return ((q && q->name) ? q->name : "unknown");
 }
 #endif