diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2025-01-14 19:53:10 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-01-15 19:13:33 -0800 |
| commit | 5fda3f35349b6b7f22f5f5095a3821261d515075 (patch) | |
| tree | b0f63293e9056809bb945957d58c9c8567a0367e | |
| parent | ebda2f0bbde540ff7da168d2837f8cfb14581e2e (diff) | |
net: make netdev_lock() protect netdev->reg_state
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@fastly.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250115035319.559603-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/linux/netdevice.h | 2 | ||||
| -rw-r--r-- | net/core/dev.c | 6 |
2 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 6d440db35d5f..007bcfa383c9 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2448,7 +2448,7 @@ 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 47e6b0f73cfc..bbe6fb9e32cd 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10695,7 +10695,9 @@ 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; @@ -10969,7 +10971,9 @@ void netdev_run_todo(void) continue; } + netdev_lock(dev); WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED); + netdev_unlock(dev); linkwatch_sync_dev(dev); } @@ -11575,7 +11579,9 @@ 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(); |