releases/2.6.37.5/sunrpc-ensure-we-always-run-the-tk_callback-before-tk_action.patch

   1 From e020c6800c9621a77223bf2c1ff68180e41e8ebf Mon Sep 17 00:00:00 2001
   2 From: Trond Myklebust <Trond.Myklebust@netapp.com>
   3 Date: Tue, 15 Mar 2011 19:56:30 -0400
   4 Subject: SUNRPC: Ensure we always run the tk_callback before tk_action
   5
   6 From: Trond Myklebust <Trond.Myklebust@netapp.com>
   7
   8 commit e020c6800c9621a77223bf2c1ff68180e41e8ebf upstream.
   9
  10 This fixes a race in which the task->tk_callback() puts the rpc_task
  11 to sleep, setting a new callback. Under certain circumstances, the current
  12 code may end up executing the task->tk_action before it gets round to the
  13 callback.
  14
  15 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
  16 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  17
  18 ---
  19  net/sunrpc/sched.c |   14 ++++++--------
  20  1 file changed, 6 insertions(+), 8 deletions(-)
  21
  22 --- a/net/sunrpc/sched.c
  23 +++ b/net/sunrpc/sched.c
  24 @@ -623,14 +623,12 @@ static void __rpc_execute(struct rpc_tas
  25                         save_callback = task->tk_callback;
  26                         task->tk_callback = NULL;
  27                         save_callback(task);
  28 -               }
  29 -
  30 -               /*
  31 -                * Perform the next FSM step.
  32 -                * tk_action may be NULL when the task has been killed
  33 -                * by someone else.
  34 -                */
  35 -               if (!RPC_IS_QUEUED(task)) {
  36 +               } else {
  37 +                       /*
  38 +                        * Perform the next FSM step.
  39 +                        * tk_action may be NULL when the task has been killed
  40 +                        * by someone else.
  41 +                        */
  42                         if (task->tk_action == NULL)
  43                                 break;
  44                         task->tk_action(task);