6.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Kicinski <kuba@xxxxxxxxxx> [ Upstream commit 5fda3f35349b6b7f22f5f5095a3821261d515075 ] Protect writes to netdev->reg_state with netdev_lock(). >From now on holding netdev_lock() is sufficient to prevent the net_device from getting unregistered, so code which wants to hold just a single netdev around no longer needs to hold rtnl_lock. We do not protect the NETREG_UNREGISTERED -> NETREG_RELEASED transition. We'd need to move mutex_destroy(netdev->lock) to .release, but the real reason is that trying to stop the unregistration process mid-way would be unsafe / crazy. Taking references on such devices is not safe, either. So the intended semantics are to lock REGISTERED devices. Reviewed-by: Joe Damato <jdamato@xxxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Link: https://patch.msgid.link/20250115035319.559603-3-kuba@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Stable-dep-of: 011b03359038 ("Revert "net: skb: introduce and use a single page frag cache"") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- include/linux/netdevice.h | 2 +- net/core/dev.c | 6 ++++++ 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 035cc881dd756..47f817bcea503 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2446,7 +2446,7 @@ struct net_device { * Should always be taken using netdev_lock() / netdev_unlock() helpers. * Drivers are free to use it for other protection. * - * Protects: @net_shaper_hierarchy. + * Protects: @reg_state, @net_shaper_hierarchy. * Ordering: take after rtnl_lock. */ struct mutex lock; diff --git a/net/core/dev.c b/net/core/dev.c index 09a9adfa7da99..75996e1aac46c 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10656,7 +10656,9 @@ int register_netdevice(struct net_device *dev) ret = netdev_register_kobject(dev); + netdev_lock(dev); WRITE_ONCE(dev->reg_state, ret ? NETREG_UNREGISTERED : NETREG_REGISTERED); + netdev_unlock(dev); if (ret) goto err_uninit_notify; @@ -10954,7 +10956,9 @@ void netdev_run_todo(void) continue; } + netdev_lock(dev); WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED); + netdev_unlock(dev); linkwatch_sync_dev(dev); } @@ -11560,7 +11564,9 @@ void unregister_netdevice_many_notify(struct list_head *head, list_for_each_entry(dev, head, unreg_list) { /* And unlink it from device chain. */ unlist_netdevice(dev); + netdev_lock(dev); WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERING); + netdev_unlock(dev); } flush_all_backlogs(); -- 2.39.5
