Patchwork bonding: fix locking in enslave failure path

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Submitter Nikolay Aleksandrov
Date April 22, 2013, 6:12 p.m.
Message ID <1366654342-2715-1-git-send-email-nikolay@redhat.com>
Download mbox | patch
Permalink /patch/238611/
State Accepted
Delegated to: David Miller
Headers show

Comments

Nikolay Aleksandrov - April 22, 2013, 6:12 p.m.
In commit 3c5913b53fefc9d9e15a2d0f93042766658d9f3f ("bonding:
primary_slave & curr_active_slave are not cleaned on enslave failure")
I didn't account for the use of curr_active_slave without curr_slave_lock
and since there are such users, we should hold bond->lock for writing while
setting it to NULL (in the NULL case we don't need the curr_slave_lock).
Keeping the bond lock as to avoid the extra release/acquire cycle.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
---
 drivers/net/bonding/bond_main.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
David Miller - April 25, 2013, 8:04 a.m.
From: Nikolay Aleksandrov <nikolay@redhat.com>
Date: Mon, 22 Apr 2013 20:12:22 +0200

> In commit 3c5913b53fefc9d9e15a2d0f93042766658d9f3f ("bonding:
> primary_slave & curr_active_slave are not cleaned on enslave failure")
> I didn't account for the use of curr_active_slave without curr_slave_lock
> and since there are such users, we should hold bond->lock for writing while
> setting it to NULL (in the NULL case we don't need the curr_slave_lock).
> Keeping the bond lock as to avoid the extra release/acquire cycle.
> 
> Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>

Applied, thanks.
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Patch

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index dbbea0e..7db40de1 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1915,14 +1915,16 @@  err_detach:
 	bond_detach_slave(bond, new_slave);
 	if (bond->primary_slave == new_slave)
 		bond->primary_slave = NULL;
-	write_unlock_bh(&bond->lock);
 	if (bond->curr_active_slave == new_slave) {
+		bond_change_active_slave(bond, NULL);
+		write_unlock_bh(&bond->lock);
 		read_lock(&bond->lock);
 		write_lock_bh(&bond->curr_slave_lock);
-		bond_change_active_slave(bond, NULL);
 		bond_select_active_slave(bond);
 		write_unlock_bh(&bond->curr_slave_lock);
 		read_unlock(&bond->lock);
+	} else {
+		write_unlock_bh(&bond->lock);
 	}
 	slave_disable_netpoll(new_slave);