From 04efcee6ef8d0f01eef495db047e7216d6e6e38f Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 4 Apr 2025 09:11:22 -0700 Subject: net: hold instance lock during NETDEV_CHANGE Cosmin reports an issue with ipv6_add_dev being called from NETDEV_CHANGE notifier: [ 3455.008776] ? ipv6_add_dev+0x370/0x620 [ 3455.010097] ipv6_find_idev+0x96/0xe0 [ 3455.010725] addrconf_add_dev+0x1e/0xa0 [ 3455.011382] addrconf_init_auto_addrs+0xb0/0x720 [ 3455.013537] addrconf_notify+0x35f/0x8d0 [ 3455.014214] notifier_call_chain+0x38/0xf0 [ 3455.014903] netdev_state_change+0x65/0x90 [ 3455.015586] linkwatch_do_dev+0x5a/0x70 [ 3455.016238] rtnl_getlink+0x241/0x3e0 [ 3455.019046] rtnetlink_rcv_msg+0x177/0x5e0 Similarly, linkwatch might get to ipv6_add_dev without ops lock: [ 3456.656261] ? ipv6_add_dev+0x370/0x620 [ 3456.660039] ipv6_find_idev+0x96/0xe0 [ 3456.660445] addrconf_add_dev+0x1e/0xa0 [ 3456.660861] addrconf_init_auto_addrs+0xb0/0x720 [ 3456.661803] addrconf_notify+0x35f/0x8d0 [ 3456.662236] notifier_call_chain+0x38/0xf0 [ 3456.662676] netdev_state_change+0x65/0x90 [ 3456.663112] linkwatch_do_dev+0x5a/0x70 [ 3456.663529] __linkwatch_run_queue+0xeb/0x200 [ 3456.663990] linkwatch_event+0x21/0x30 [ 3456.664399] process_one_work+0x211/0x610 [ 3456.664828] worker_thread+0x1cc/0x380 [ 3456.665691] kthread+0xf4/0x210 Reclassify NETDEV_CHANGE as a notifier that consistently runs under the instance lock. Link: https://lore.kernel.org/netdev/aac073de8beec3e531c86c101b274d434741c28e.camel@nvidia.com/ Reported-by: Cosmin Ratiu Tested-by: Cosmin Ratiu Fixes: ad7c7b2172c3 ("net: hold netdev instance lock during sysfs operations") Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250404161122.3907628-1-sdf@fomichev.me Signed-off-by: Jakub Kicinski --- Documentation/networking/netdevices.rst | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'Documentation/networking') diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst index 6c2d8945f597..eab601ab2db0 100644 --- a/Documentation/networking/netdevices.rst +++ b/Documentation/networking/netdevices.rst @@ -338,10 +338,11 @@ operations directly under the netdev instance lock. Devices drivers are encouraged to rely on the instance lock where possible. For the (mostly software) drivers that need to interact with the core stack, -there are two sets of interfaces: ``dev_xxx`` and ``netif_xxx`` (e.g., -``dev_set_mtu`` and ``netif_set_mtu``). The ``dev_xxx`` functions handle -acquiring the instance lock themselves, while the ``netif_xxx`` functions -assume that the driver has already acquired the instance lock. +there are two sets of interfaces: ``dev_xxx``/``netdev_xxx`` and ``netif_xxx`` +(e.g., ``dev_set_mtu`` and ``netif_set_mtu``). The ``dev_xxx``/``netdev_xxx`` +functions handle acquiring the instance lock themselves, while the +``netif_xxx`` functions assume that the driver has already acquired +the instance lock. Notifiers and netdev instance lock ================================== @@ -354,6 +355,7 @@ For devices with locked ops, currently only the following notifiers are running under the lock: * ``NETDEV_REGISTER`` * ``NETDEV_UP`` +* ``NETDEV_CHANGE`` The following notifiers are running without the lock: * ``NETDEV_UNREGISTER`` -- cgit v1.2.3