From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 656BA3F39E4; Fri, 4 Sep 2026 18:01:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788544865; cv=none; b=e7OWCIAftqnRB8s5CmrX4fvWGCuPBSRpnkfHQPEBfEvzlFX+fsd6Q8LBVvpUDxUwTx7NK5pn7duOS0/WL8lgabCQGUYS5bFijSjrOS6404jRZKTriu9xpDfY17Yr6DQ5/B3yf6ZYnEPz5R0exQYzy1hPF5Uo/hCL9NOtOKyws7s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788544865; c=relaxed/simple; bh=IyV4SeHzlGQh/XTrkjNBkEM1WrROfiZ2BH4a1VtThAc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ni9kDUgTCjqfNIiI/+mDr8FzTvdQRuvgZw73gTobqkfE8q5Z/FL+MZ1A2avsVZ/EkXx5O/QSlkpPi7QCQaSKZIUkwJSSY6DGTh/fFVy6DewRIInUeXyNeuoQOV39iS25D6WX1o1ntF2yMVe5e/gg9q5v73I0wdH9sROGwnkrFiQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iOQms9UY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iOQms9UY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB7971F00A3D; Fri, 4 Sep 2026 18:01:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788544862; bh=Sh4pM9P10ktTurWhj1Ao4Irjykp6UovFXYEZeKiGJ3c=; h=From:To:Cc:Subject:Date; b=iOQms9UYSodcECCBoYxOpngCu1awd0x7Oca9IG4wmg4vlpxDKIlE/DhgQAID8ZNcK tQ8Jj44QRdzJUDcx/WPQlBdU7DPYYLt80jKNwSf5FwLUL+LZnMXCXvnxB2x7F8EHDj tSNMOldqDe5aMI/mr3KubNV8mDjWwjUAqWy/+9HvHYBx9SFpXwlmiJ0HB81CuzZN+/ HHjTYqsgCk30ZIh3UMHVZdqu27vG6qwnd3iwT85WjNVYeggG6vuyY3GKaphXkjZlV3 Gdky5JulPZ6VCYJ2xw4N33aoU6OeRW/Rn1NNiIr4G7vNvpPcyqIeRKDwl4hdk0+hM/ 0eNEglWxFjZiw== From: Jakub Kicinski To: davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, Jakub Kicinski , corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, sdf@fomichev.me, kuniyu@google.com, linux-doc@vger.kernel.org Subject: [PATCH net-next] net: run netdev work under the ops-compat lock Date: Fri, 4 Sep 2026 11:00:58 -0700 Message-ID: <20260904180058.3803849-1-kuba@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit netdev_work_proc() took rtnl_lock() for the whole batch, forcing even ops-locked drivers onto rtnl just to run their rx_mode / ndo_work callbacks. Take the per-device ops-compat lock instead: the instance lock for ops-locked drivers, rtnl_lock for the rest. That's what the callbacks already assert (e.g. netif_rx_mode_run() asserts netdev_assert_locked_ops_compat()), and non-ops-locked work such as vlan ndo_work keeps rtnl, since its compat lock resolves to rtnl anyway. Without this adding more uses of ndo_work, for cases which don't need rtnl_lock feels like a step back. We can drop the comment about the extra ref now, with the relocking it's a necessity. Signed-off-by: Jakub Kicinski --- CC: corbet@lwn.net CC: skhan@linuxfoundation.org CC: rdunlap@infradead.org CC: sdf@fomichev.me CC: kuniyu@google.com CC: linux-doc@vger.kernel.org --- Documentation/networking/netdevices.rst | 14 ++++++++++---- include/linux/netdevice.h | 5 ++++- net/core/netdev_work.c | 15 ++------------- 3 files changed, 16 insertions(+), 18 deletions(-) diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst index db71d4283032..aac33497813f 100644 --- a/Documentation/networking/netdevices.rst +++ b/Documentation/networking/netdevices.rst @@ -292,15 +292,21 @@ struct net_device synchronization rules in process context. ndo_set_rx_mode_async: - Synchronization: rtnl_lock() semaphore. In addition, netdev instance - lock if the driver implements queue management or shaper API. + Synchronization: netdev instance lock for "ops locked" drivers, + rtnl_lock() semaphore for all other drivers. Context: process (from a work queue) Notes: Async version of ndo_set_rx_mode which runs in process context. Receives snapshots of the unicast and multicast address lists. ndo_change_rx_flags: - Synchronization: rtnl_lock() semaphore. In addition, netdev instance - lock if the driver implements queue management or shaper API. + Synchronization: netdev instance lock for "ops locked" drivers, + rtnl_lock() semaphore for all other drivers. + +ndo_work: + Synchronization: netdev instance lock for "ops locked" drivers, + rtnl_lock() semaphore for all other drivers. + Context: process (from a work queue) + Notes: Runs deferred work scheduled with netdev_work_sched(). ndo_setup_tc: Locking depends on ``tc_setup_type``. For most types the callback diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 8454646d6a45..17b8fb8e94fe 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1135,13 +1135,16 @@ struct netdev_net_notifier { * struct netdev_hw_addr_list *uc, * struct netdev_hw_addr_list *mc); * Async version of ndo_set_rx_mode which runs in process context - * with rtnl_lock and netdev_lock_ops(dev) held. The uc/mc parameters + * under the netdev instance lock for "ops locked" drivers, or + * rtnl_lock for all other drivers. The uc/mc parameters * are snapshots of the address lists - iterate with * netdev_hw_addr_list_for_each(ha, uc). Return 0 on success or a * negative errno to request a retry via the core backoff. * * void (*ndo_work)(struct net_device *dev, unsigned long events); * Run deferred work scheduled with netdev_work_sched(@events). + * Runs in process context under the netdev instance lock for "ops + * locked" drivers, or rtnl_lock for all other drivers. * * int (*ndo_set_mac_address)(struct net_device *dev, void *addr); * This function is called when the Media Access Control address diff --git a/net/core/netdev_work.c b/net/core/netdev_work.c index e721a06d58df..c99967907e18 100644 --- a/net/core/netdev_work.c +++ b/net/core/netdev_work.c @@ -3,7 +3,6 @@ #include #include #include -#include #include #include #include @@ -129,8 +128,6 @@ static void netdev_work_run(struct net_device *dev, unsigned long events, static void netdev_work_proc(struct work_struct *work) { - rtnl_lock(); - while (true) { unsigned long events = 0, core = 0; netdevice_tracker tracker; @@ -143,16 +140,10 @@ static void netdev_work_proc(struct work_struct *work) } dev = list_first_entry(&netdev_work_list, struct net_device, work_node); - /* Take a temporary reference so @dev can't be freed while we - * drop the lock to grab its ops lock; the work reference is - * only released once we claim the work below. - * The re-locking dance is to ensure that ops lock is enough - * to ensure canceling work is not racy with dequeue. - */ netdev_hold(dev, &tracker, GFP_ATOMIC); spin_unlock_bh(&netdev_work_lock); - netdev_lock_ops(dev); + netdev_lock_ops_compat(dev); spin_lock_bh(&netdev_work_lock); if (!list_empty(&dev->work_node)) { list_del_init(&dev->work_node); @@ -169,10 +160,8 @@ static void netdev_work_proc(struct work_struct *work) spin_unlock_bh(&netdev_work_lock); netdev_work_run(dev, events, core); - netdev_unlock_ops(dev); + netdev_unlock_ops_compat(dev); netdev_put(dev, &tracker); } - - rtnl_unlock(); } -- 2.55.0