[PATCH net-next] net: run netdev work under the ops-compat lock
From: Jakub Kicinski <kuba@kernel.org>
Date: 2026-09-04 18:01:02
Also in:
netdev
Subsystem:
documentation, networking drivers, networking [general], the rest · Maintainers:
Jonathan Corbet, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <kuba@kernel.org> --- 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 <linux/export.h> #include <linux/list.h> #include <linux/netdevice.h> -#include <linux/rtnetlink.h> #include <linux/spinlock.h> #include <linux/workqueue.h> #include <net/netdev_lock.h>
@@ -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