Merge tag 'nfs-for-3.10-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:

 - Stable fix to prevent an rpc_task wakeup race
 - Fix a NFSv4.1 session drain deadlock
 - Fix a NFSv4/v4.1 mount regression when not running rpc.gssd
 - Ensure auth_gss pipe detection works in namespaces
 - Fix SETCLIENTID fallback if rpcsec_gss is not available

* tag 'nfs-for-3.10-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: Fix SETCLIENTID fallback if GSS is not available
  SUNRPC: Prevent an rpc_task wakeup race
  NFSv4.1 Fix a pNFS session draining deadlock
  SUNRPC: Convert auth_gss pipe detection to work in namespaces
  SUNRPC: Faster detection if gssd is actually running
  SUNRPC: Fix a bug in gss_create_upcall

1 files changed, 7 insertions, 1 deletions

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index f8529fc8e542..5356b120dbf8 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -324,11 +324,17 @@ EXPORT_SYMBOL_GPL(__rpc_wait_for_completion_task);
  * Note: If the task is ASYNC, and is being made runnable after sitting on an
  * rpc_wait_queue, this must be called with the queue spinlock held to protect
  * the wait queue operation.
+ * Note the ordering of rpc_test_and_set_running() and rpc_clear_queued(),
+ * which is needed to ensure that __rpc_execute() doesn't loop (due to the
+ * lockless RPC_IS_QUEUED() test) before we've had a chance to test
+ * the RPC_TASK_RUNNING flag.
  */
 static void rpc_make_runnable(struct rpc_task *task)
 {
+	bool need_wakeup = !rpc_test_and_set_running(task);
+
 	rpc_clear_queued(task);
-	if (rpc_test_and_set_running(task))
+	if (!need_wakeup)
 		return;
 	if (RPC_IS_ASYNC(task)) {
 		INIT_WORK(&task->u.tk_work, rpc_async_schedule);