linux-kernel - Re: [syzbot] [net?] possible deadlock in team_del

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Message-Id: <20240703134439.79904-1-aha310510@gmail.com>
Date: Wed,  3 Jul 2024 22:44:39 +0900
From: Jeongjun Park <aha310510@...il.com>
To: syzbot+705c61d60b091ef42c04@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] possible deadlock in team_del_slave (3)

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
 drivers/net/team/team_core.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c
index ab1935a4aa2c..3ac82df876b0 100644
--- a/drivers/net/team/team_core.c
+++ b/drivers/net/team/team_core.c
@@ -1970,11 +1970,12 @@ static int team_add_slave(struct net_device *dev, struct net_device *port_dev,
                          struct netlink_ext_ack *extack)
 {
        struct team *team = netdev_priv(dev);
-       int err;
+       int err, locked;
 
-       mutex_lock(&team->lock);
+       locked = mutex_trylock(&team->lock);
        err = team_port_add(team, port_dev, extack);
-       mutex_unlock(&team->lock);
+       if (locked)
+               mutex_unlock(&team->lock);
 
        if (!err)
                netdev_change_features(dev);
@@ -1985,11 +1986,12 @@ static int team_add_slave(struct net_device *dev, struct net_device *port_dev,
 static int team_del_slave(struct net_device *dev, struct net_device *port_dev)
 {
        struct team *team = netdev_priv(dev);
-       int err;
+       int err, locked;
 
-       mutex_lock(&team->lock);
+       locked = mutex_trylock(&team->lock);
        err = team_port_del(team, port_dev);
-       mutex_unlock(&team->lock);
+       if (locked)
+               mutex_unlock(&team->lock);
 
        if (err)
                return err;
--