diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2026-08-05 19:28:21 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-08-06 09:37:03 -0700 |
| commit | d31c14e56a4f01f0689c29c0bcbcd45f65b4a473 (patch) | |
| tree | 2140c6c7e07b4101036380b6b0d4210fbf4ae78f /net/core | |
| parent | 8e63c9e6179ace3033dcd19991f95386e9d3130f (diff) | |
net: avoid theoretical races with ref drain
Technically, it's illegal to take a ref on a netdev just because
we have a pointer on which we already hold a ref, with no other
protection. This is because our simple per-cpu refcount
implementation cannot atomically read the count.
Let's make sure we cancel outstanding work and never queue more
work for a device we know is dead. This way taking a ref on
a dev we know is on the netdev_work_list is always going to be safe.
Jiangshan Yi reports that the issues is caught by ref tracker infra
leading to a warning:
WARNING: lib/ref_tracker.c:322 at ref_tracker_free
WARNING: lib/ref_tracker.c:246 at ref_tracker_dir_exit
Reported-by: Jiangshan Yi <yijiangshan@kylinos.cn>
Link: https://lore.kernel.org/20260731035135.3917308-2-yijiangshan@kylinos.cn
Fixes: 12c765be84d2 ("net: turn the rx_mode work into a generic netdev_work facility")
Link: https://patch.msgid.link/20260806022821.2079945-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 1 | ||||
| -rw-r--r-- | net/core/dev.h | 1 | ||||
| -rw-r--r-- | net/core/netdev_work.c | 16 |
3 files changed, 18 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index c49d2ce51285..af260ff5462a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -12436,6 +12436,7 @@ void unregister_netdevice_many_notify(struct list_head *head, dev_tcx_uninstall(dev); dev_xdp_uninstall(dev); dev_memory_provider_uninstall(dev); + netdev_work_cancel_all(dev); netdev_unlock_ops(dev); bpf_dev_bound_netdev_unregister(dev); diff --git a/net/core/dev.h b/net/core/dev.h index 5d0b0305d3ba..b757faead4d1 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -179,6 +179,7 @@ enum netdev_work_core { void __netdev_work_core_sched(struct net_device *dev, unsigned long event); unsigned long __netdev_work_core_cancel(struct net_device *dev, unsigned long mask); +void netdev_work_cancel_all(struct net_device *dev); void __dev_notify_flags(struct net_device *dev, unsigned int old_flags, unsigned int gchanges, u32 portid, diff --git a/net/core/netdev_work.c b/net/core/netdev_work.c index 3109fae132ad..e721a06d58df 100644 --- a/net/core/netdev_work.c +++ b/net/core/netdev_work.c @@ -31,6 +31,10 @@ static void netdev_work_enqueue(struct net_device *dev, unsigned long events, return; spin_lock_bh(&netdev_work_lock); + if (!dev_isalive(dev)) { + spin_unlock_bh(&netdev_work_lock); + return; + } if (list_empty(&dev->work_node)) { list_add_tail(&dev->work_node, &netdev_work_list); netdev_hold(dev, &dev->work_tracker, GFP_ATOMIC); @@ -61,6 +65,18 @@ netdev_work_dequeue(struct net_device *dev, unsigned long *pending, return events; } +void netdev_work_cancel_all(struct net_device *dev) +{ + spin_lock_bh(&netdev_work_lock); + dev->work_pending = 0; + dev->work_core_pending = 0; + if (!list_empty(&dev->work_node)) { + list_del_init(&dev->work_node); + netdev_put(dev, &dev->work_tracker); + } + spin_unlock_bh(&netdev_work_lock); +} + void netdev_work_sched(struct net_device *dev, unsigned long events) { netdev_work_enqueue(dev, events, 0); |