net: add option to request netdev instance lock

Currently only the drivers that implement shaper or queue APIs
are grabbing instance lock. Add an explicit opt-in for the
drivers that want to grab the lock without implementing the above
APIs.

There is a 3-byte hole after @up, use it:

        /* --- cacheline 47 boundary (3008 bytes) --- */
        u32                        napi_defer_hard_irqs; /*  3008     4 */
        bool                       up;                   /*  3012     1 */

        /* XXX 3 bytes hole, try to pack */

        struct mutex               lock;                 /*  3016   144 */

        /* XXX last struct has 1 hole */

Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-13-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f3e6e6f27e22c9e750e40b087f971f8bb6661b93..adf201617b72f85b464f4e5202321e7c2e97455a 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2485,6 +2485,12 @@ struct net_device {
         */
        bool                    up;
 
+       /**
+        * @request_ops_lock: request the core to run all @netdev_ops and
+        * @ethtool_ops under the @lock.
+        */
+       bool                    request_ops_lock;
+
        /**
         * @lock: netdev-scope lock, protects a small selection of fields.
         * Should always be taken using netdev_lock() / netdev_unlock() helpers.
@@ -2774,7 +2780,7 @@ static inline void netdev_assert_locked_or_invisible(struct net_device *dev)
 
 static inline bool netdev_need_ops_lock(struct net_device *dev)
 {
-       bool ret = !!dev->queue_mgmt_ops;
+       bool ret = dev->request_ops_lock || !!dev->queue_mgmt_ops;
 
 #if IS_ENABLED(CONFIG_NET_SHAPER)
        ret |= !!dev->netdev_ops->net_shaper_ops;