[34-longterm 192/247] SUNRPC: Ensure we always run the tk_callback before tk_action

Paul Gortmaker
2011-06-23T17:38:04Z

From: Trond Myklebust <Trond.Myklebust@netapp.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

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@netapp.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
net/sunrpc/sched.c | 14 ++++++--------
1 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index aae6907..03a5c9e 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -642,14 +642,12 @@ static void __rpc_execute(struct rpc_task *task)
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);
--
1.7.4.4