This is a note to let you know that I've just added the patch titled alx: acquire mutex for alx_reinit in alx_change_mtu to the 5.15-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: alx-acquire-mutex-for-alx_reinit-in-alx_change_mtu.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit a1ec67adaeadb5ac432b893d58f8c5246764b638 Author: Niels Dossche <dossche.niels@xxxxxxxxx> Date: Fri Mar 11 00:27:08 2022 +0100 alx: acquire mutex for alx_reinit in alx_change_mtu [ Upstream commit 46b348fd2d81a341b15fb3f3f986204b038f5c42 ] alx_reinit has a lockdep assertion that the alx->mtx mutex must be held. alx_reinit is called from two places: alx_reset and alx_change_mtu. alx_reset does acquire alx->mtx before calling alx_reinit. alx_change_mtu does not acquire this mutex, nor do its callers or any path towards alx_change_mtu. Acquire the mutex in alx_change_mtu. The issue was introduced when the fine-grained locking was introduced to the code to replace the RTNL. The same commit also introduced the lockdep assertion. Fixes: 4a5fe57e7751 ("alx: use fine-grained locking instead of RTNL") Signed-off-by: Niels Dossche <dossche.niels@xxxxxxxxx> Link: https://lore.kernel.org/r/20220310232707.44251-1-dossche.niels@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c index 4ea157efca86..98a8698a3201 100644 --- a/drivers/net/ethernet/atheros/alx/main.c +++ b/drivers/net/ethernet/atheros/alx/main.c @@ -1181,8 +1181,11 @@ static int alx_change_mtu(struct net_device *netdev, int mtu) alx->hw.mtu = mtu; alx->rxbuf_size = max(max_frame, ALX_DEF_RXBUF_SIZE); netdev_update_features(netdev); - if (netif_running(netdev)) + if (netif_running(netdev)) { + mutex_lock(&alx->mtx); alx_reinit(alx); + mutex_unlock(&alx->mtx); + } return 0; }