This is a note to let you know that I've just added the patch titled
team: avoid possible underflow of count_pending value for notify_peers and mcast_rejoin
to the 3.18-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-possible-underflow-of-count_pending-value-for-notify_peers-and-mcast_rejoin.patch
and it can be found in the queue-3.18 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 Sat Jan 17 18:12:21 PST 2015
From: Jiri Pirko <jiri@xxxxxxxxxxx>
Date: Wed, 14 Jan 2015 18:15:30 +0100
Subject: team: avoid possible underflow of count_pending value for notify_peers and mcast_rejoin
From: Jiri Pirko <jiri@xxxxxxxxxxx>
[ Upstream commit b0d11b42785b70e19bc6a3122eead3f7969a7589 ]
This patch is fixing a race condition that may cause setting
count_pending to -1, which results in unwanted big bulk of arp messages
(in case of "notify peers").
Consider following scenario:
count_pending == 2
CPU0 CPU1
team_notify_peers_work
atomic_dec_and_test (dec count_pending to 1)
schedule_delayed_work
team_notify_peers
atomic_add (adding 1 to count_pending)
team_notify_peers_work
atomic_dec_and_test (dec count_pending to 1)
schedule_delayed_work
team_notify_peers_work
atomic_dec_and_test (dec count_pending to 0)
schedule_delayed_work
team_notify_peers_work
atomic_dec_and_test (dec count_pending to -1)
Fix this race by using atomic_dec_if_positive - that will prevent
count_pending running under 0.
Fixes: fc423ff00df3a1955441 ("team: add peer notification")
Fixes: 492b200efdd20b8fcfd ("team: add support for sending multicast rejoins")
Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxx>
Signed-off-by: Jiri Benc <jbenc@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/team/team.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -629,6 +629,7 @@ static int team_change_mode(struct team
static void team_notify_peers_work(struct work_struct *work)
{
struct team *team;
+ int val;
team = container_of(work, struct team, notify_peers.dw.work);
@@ -636,9 +637,14 @@ static void team_notify_peers_work(struc
schedule_delayed_work(&team->notify_peers.dw, 0);
return;
}
+ val = atomic_dec_if_positive(&team->notify_peers.count_pending);
+ if (val < 0) {
+ rtnl_unlock();
+ return;
+ }
call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, team->dev);
rtnl_unlock();
- if (!atomic_dec_and_test(&team->notify_peers.count_pending))
+ if (val)
schedule_delayed_work(&team->notify_peers.dw,
msecs_to_jiffies(team->notify_peers.interval));
}
@@ -669,6 +675,7 @@ static void team_notify_peers_fini(struc
static void team_mcast_rejoin_work(struct work_struct *work)
{
struct team *team;
+ int val;
team = container_of(work, struct team, mcast_rejoin.dw.work);
@@ -676,9 +683,14 @@ static void team_mcast_rejoin_work(struc
schedule_delayed_work(&team->mcast_rejoin.dw, 0);
return;
}
+ val = atomic_dec_if_positive(&team->mcast_rejoin.count_pending);
+ if (val < 0) {
+ rtnl_unlock();
+ return;
+ }
call_netdevice_notifiers(NETDEV_RESEND_IGMP, team->dev);
rtnl_unlock();
- if (!atomic_dec_and_test(&team->mcast_rejoin.count_pending))
+ if (val)
schedule_delayed_work(&team->mcast_rejoin.dw,
msecs_to_jiffies(team->mcast_rejoin.interval));
}
Patches currently in stable-queue which might be from jiri@xxxxxxxxxxx are
queue-3.18/team-avoid-possible-underflow-of-count_pending-value-for-notify_peers-and-mcast_rejoin.patch
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