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([128.14.159.2]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2f88847502fsm16347837eec.14.2026.05.11.07.06.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2026 07:06:12 -0700 (PDT) From: faicker.mo@gmail.com To: faicker.mo@gmail.com Cc: Sridhar Samudrala , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Stanislav Fomichev , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4] net: net_failover: Fix the deadlock in slave register Date: Mon, 11 May 2026 22:05:51 +0800 Message-Id: <20260511140552.3284563-1-faicker.mo@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Faicker Mo There is netdev_lock_ops() before the NETDEV_REGISTER notifier in register_netdevice(), so use the non-locking functions in net_failover_slave_register(). failover_slave_register() in failover_existing_slave_register() adds lock and unlock ops too. Call Trace: __schedule+0x30d/0x7a0 schedule+0x27/0x90 schedule_preempt_disabled+0x15/0x30 __mutex_lock.constprop.0+0x538/0x9e0 __mutex_lock_slowpath+0x13/0x20 mutex_lock+0x3b/0x50 dev_set_mtu+0x40/0xe0 net_failover_slave_register+0x24/0x280 failover_slave_register+0x103/0x1b0 failover_event+0x15e/0x210 ? dropmon_net_event+0xac/0xe0 notifier_call_chain+0x5e/0xe0 raw_notifier_call_chain+0x16/0x30 call_netdevice_notifiers_info+0x52/0xa0 register_netdevice+0x5f4/0x7c0 register_netdev+0x1e/0x40 _mlx5e_probe+0xe2/0x370 [mlx5_core] mlx5e_probe+0x59/0x70 [mlx5_core] ? __pfx_mlx5e_probe+0x10/0x10 [mlx5_core] Fixes: 4c975fd70002 ("net: hold instance lock during NETDEV_REGISTER/UP") Signed-off-by: Faicker Mo --- Changes since v1: - Fix the space chars (Simon) - Change the dev_close to netif_close (Simon) - Change the label err_dev_open to err_netif_open Changes since v2: - Add lock ops in failover_existing_slave_register (Jakub Kicinski) Changes since v3: - Fix the lock ops implicit declaration (Jakub Kicinski) --- drivers/net/net_failover.c | 12 ++++++------ net/core/failover.c | 6 +++++- 2 files changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/net/net_failover.c b/drivers/net/net_failover.c index d0361aaf25ef..3f7d31033bae 100644 --- a/drivers/net/net_failover.c +++ b/drivers/net/net_failover.c @@ -502,7 +502,7 @@ static int net_failover_slave_register(struct net_device *slave_dev, /* Align MTU of slave with failover dev */ orig_mtu = slave_dev->mtu; - err = dev_set_mtu(slave_dev, failover_dev->mtu); + err = netif_set_mtu(slave_dev, failover_dev->mtu); if (err) { netdev_err(failover_dev, "unable to change mtu of %s to %u register failed\n", slave_dev->name, failover_dev->mtu); @@ -512,11 +512,11 @@ static int net_failover_slave_register(struct net_device *slave_dev, dev_hold(slave_dev); if (netif_running(failover_dev)) { - err = dev_open(slave_dev, NULL); + err = netif_open(slave_dev, NULL); if (err && (err != -EBUSY)) { netdev_err(failover_dev, "Opening slave %s failed err:%d\n", slave_dev->name, err); - goto err_dev_open; + goto err_netif_open; } } @@ -562,10 +562,10 @@ static int net_failover_slave_register(struct net_device *slave_dev, err_vlan_add: dev_uc_unsync(slave_dev, failover_dev); dev_mc_unsync(slave_dev, failover_dev); - dev_close(slave_dev); -err_dev_open: + netif_close(slave_dev); +err_netif_open: dev_put(slave_dev); - dev_set_mtu(slave_dev, orig_mtu); + netif_set_mtu(slave_dev, orig_mtu); done: return err; } diff --git a/net/core/failover.c b/net/core/failover.c index 11bb183c7a1b..e43c59cd6868 100644 --- a/net/core/failover.c +++ b/net/core/failover.c @@ -12,6 +12,7 @@ #include #include #include +#include #include static LIST_HEAD(failover_list); @@ -221,8 +222,11 @@ failover_existing_slave_register(struct net_device *failover_dev) for_each_netdev(net, dev) { if (netif_is_failover(dev)) continue; - if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr)) + if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr)) { + netdev_lock_ops(dev); failover_slave_register(dev); + netdev_unlock_ops(dev); + } } rtnl_unlock(); } -- 2.34.1