This is a note to let you know that I've just added the patch titled
net: bonding: correctly annotate RCU in bond_should_notify_peers()
to the 4.19-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:
net-bonding-correctly-annotate-rcu-in-bond_should_no.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3ebd35a9a0aa902cfb4b47537b55b8dafbd7e856
Author: Johannes Berg <johannes.berg@xxxxxxxxx>
Date: Fri Jul 19 09:41:18 2024 -0700
net: bonding: correctly annotate RCU in bond_should_notify_peers()
[ Upstream commit 3ba359c0cd6eb5ea772125a7aededb4a2d516684 ]
RCU use in bond_should_notify_peers() looks wrong, since it does
rcu_dereference(), leaves the critical section, and uses the
pointer after that.
Luckily, it's called either inside a nested RCU critical section
or with the RTNL held.
Annotate it with rcu_dereference_rtnl() instead, and remove the
inner RCU critical section.
Fixes: 4cb4f97b7e36 ("bonding: rebuild the lock use for bond_mii_monitor()")
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Acked-by: Jay Vosburgh <jv@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20240719094119.35c62455087d.I68eb9c0f02545b364b79a59f2110f2cf5682a8e2@changeid
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 79b36f1c50aec..f0c0da85ba4fc 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -774,13 +774,10 @@ static struct slave *bond_find_best_slave(struct bonding *bond)
return bestslave;
}
+/* must be called in RCU critical section or with RTNL held */
static bool bond_should_notify_peers(struct bonding *bond)
{
- struct slave *slave;
-
- rcu_read_lock();
- slave = rcu_dereference(bond->curr_active_slave);
- rcu_read_unlock();
+ struct slave *slave = rcu_dereference_rtnl(bond->curr_active_slave);
if (!slave || !bond->send_peer_notif ||
!netif_carrier_ok(bond->dev) ||
