Patch "team: avoid race condition in scheduling delayed work" has been added to the 3.16-stable tree

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This is a note to let you know that I've just added the patch titled

    team: avoid race condition in scheduling delayed work

to the 3.16-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     team-avoid-race-condition-in-scheduling-delayed-work.patch
and it can be found in the queue-3.16 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From foo@baz Sun Oct 12 20:11:55 CEST 2014
From: Joe Lawrence <Joe.Lawrence@xxxxxxxxxxx>
Date: Fri, 3 Oct 2014 09:58:34 -0400
Subject: team: avoid race condition in scheduling delayed work

From: Joe Lawrence <Joe.Lawrence@xxxxxxxxxxx>

[ Upstream commit 47549650abd13d873fd2e5fc218db19e21031074 ]

When team_notify_peers and team_mcast_rejoin are called, they both reset
their respective .count_pending atomic variable. Then when the actual
worker function is executed, the variable is atomically decremented.
This pattern introduces a potential race condition where the
.count_pending rolls over and the worker function keeps rescheduling
until .count_pending decrements to zero again:

THREAD 1                           THREAD 2

========                           ========
team_notify_peers(teamX)
  atomic_set count_pending = 1
  schedule_delayed_work
                                   team_notify_peers(teamX)
                                   atomic_set count_pending = 1
team_notify_peers_work
  atomic_dec_and_test
    count_pending = 0
  (return)
                                   schedule_delayed_work
                                   team_notify_peers_work
                                   atomic_dec_and_test
                                     count_pending = -1
                                   schedule_delayed_work
                                   (repeat until count_pending = 0)

Instead of assigning a new value to .count_pending, use atomic_add to
tack-on the additional desired worker function invocations.

Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Acked-by: Jiri Pirko <jiri@xxxxxxxxxxx>
Fixes: fc423ff00df3a19554414ee ("team: add peer notification")
Fixes: 492b200efdd20b8fcfdac87 ("team: add support for sending multicast rejoins")
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/team/team.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -647,7 +647,7 @@ static void team_notify_peers(struct tea
 {
 	if (!team->notify_peers.count || !netif_running(team->dev))
 		return;
-	atomic_set(&team->notify_peers.count_pending, team->notify_peers.count);
+	atomic_add(team->notify_peers.count, &team->notify_peers.count_pending);
 	schedule_delayed_work(&team->notify_peers.dw, 0);
 }
 
@@ -687,7 +687,7 @@ static void team_mcast_rejoin(struct tea
 {
 	if (!team->mcast_rejoin.count || !netif_running(team->dev))
 		return;
-	atomic_set(&team->mcast_rejoin.count_pending, team->mcast_rejoin.count);
+	atomic_add(team->mcast_rejoin.count, &team->mcast_rejoin.count_pending);
 	schedule_delayed_work(&team->mcast_rejoin.dw, 0);
 }
 


Patches currently in stable-queue which might be from Joe.Lawrence@xxxxxxxxxxx are

queue-3.16/team-avoid-race-condition-in-scheduling-delayed-work.patch
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