[PATCH] [209/275] SUNRPC: Ensure we always run the tk_callback before tk_action

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

commit e020c6800c9621a77223bf2c1ff68180e41e8ebf upstream.

This fixes a race in which the task->tk_callback() puts the rpc_task
to sleep, setting a new callback. Under certain circumstances, the current
code may end up executing the task->tk_action before it gets round to the
callback.

Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 net/sunrpc/sched.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

Index: linux-2.6.35.y/net/sunrpc/sched.c
===================================================================
--- linux-2.6.35.y.orig/net/sunrpc/sched.c	2011-03-29 22:50:35.157358829 -0700
+++ linux-2.6.35.y/net/sunrpc/sched.c	2011-03-29 23:03:02.613233304 -0700
@@ -637,14 +637,12 @@
 			save_callback = task->tk_callback;
 			task->tk_callback = NULL;
 			save_callback(task);
-		}
-
-		/*
-		 * Perform the next FSM step.
-		 * tk_action may be NULL when the task has been killed
-		 * by someone else.
-		 */
-		if (!RPC_IS_QUEUED(task)) {
+		} else {
+			/*
+			 * Perform the next FSM step.
+			 * tk_action may be NULL when the task has been killed
+			 * by someone else.
+			 */
 			if (task->tk_action == NULL)
 				break;
 			task->tk_action(task);
--
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