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thunderbolt: Use separate lock class for each ring

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When connected to another host and then unplugging cable lockdep
triggers following:

 ======================================================
 WARNING: possible circular locking dependency detected
 7.1.0-rc2+ #1775 Tainted: G     U
 ------------------------------------------------------
 kworker/u16:6/312 is trying to acquire lock:
 ffff8881179c70a8 ((work_completion)(&ring->work)){+.+.}-{0:0}, at: __flush_work+0x3cf/0xd10

 but task is already holding lock:
 ffff8881a8b810b0 (&net->connection_lock){+.+.}-{4:4}, at: tbnet_tear_down+0x110/0x720 [thunderbolt_net]

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (&net->connection_lock){+.+.}-{4:4}:
        __mutex_lock+0x19a/0x2490
        mutex_lock_nested+0x1b/0x30
        tbnet_handle_packet+0x74c/0xd70 [thunderbolt_net]
        tb_xdomain_handle_request+0x37c/0x4b0 [thunderbolt]
        tb_domain_event_cb+0xc9/0x140 [thunderbolt]
        tb_ctl_handle_event+0xd6/0x2c0 [thunderbolt]
        tb_ctl_rx_callback+0x22c/0xa10 [thunderbolt]
        ring_work+0x715/0xcb0 [thunderbolt]
        process_one_work+0x902/0x1790
        worker_thread+0x5cd/0xfe0
        kthread+0x339/0x420
        ret_from_fork+0x79a/0x9d0
        ret_from_fork_asm+0x1a/0x30

 -> #0 ((work_completion)(&ring->work)){+.+.}-{0:0}:
        __lock_acquire+0x1592/0x2640
        lock_acquire+0x1a3/0x300
        __flush_work+0x3e9/0xd10
        flush_work+0x21/0x30
        tb_ring_stop+0x240/0x840 [thunderbolt]
        tbnet_tear_down+0x2ff/0x720 [thunderbolt_net]
        tbnet_stop+0x47/0x1a0 [thunderbolt_net]
        __dev_close_many+0x19e/0x4e0
        netif_close_many+0x1e8/0x640
        unregister_netdevice_many_notify+0x6d3/0x22d0
        unregister_netdevice_queue+0x2b9/0x3a0
        unregister_netdev+0x1c/0x70
        tbnet_remove+0x52/0xb0 [thunderbolt_net]
        tb_service_remove+0x8a/0xe0 [thunderbolt]
        device_remove+0xc5/0x190
        device_release_driver_internal+0x3db/0x590
        device_release_driver+0x12/0x20
        bus_remove_device+0x2c1/0x580
        device_del+0x3d9/0x9f0
        device_unregister+0x17/0xc0
        unregister_service+0x46/0x60 [thunderbolt]
        device_for_each_child_reverse+0xfa/0x180
        tb_xdomain_unregister+0x57/0xe0 [thunderbolt]
        unregister_unplugged_xdomain+0x101/0x1a0 [thunderbolt]
        bus_for_each_dev+0x111/0x1a0
        tb_domain_unregister_unplugged_xdomains+0x98/0xe0 [thunderbolt]
        tb_handle_hotplug+0xc3/0x2bb0 [thunderbolt]
        process_one_work+0x902/0x1790
        worker_thread+0x5cd/0xfe0
        kthread+0x339/0x420
        ret_from_fork+0x79a/0x9d0
        ret_from_fork_asm+0x1a/0x30

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&net->connection_lock);
                                lock((work_completion)(&ring->work));
                                lock(&net->connection_lock);
   lock((work_completion)(&ring->work));

This in fact is false positive because they involve unrelated rings (and
unrelated work structures). In the first one it is ring 0 which is used
for control traffic and in the second it is dealing with another ring
used for the high-speed traffic.

Fix this by using separate lock class for each ring worker.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Mika Westerberg 2026-05-15 10:28:40 +03:00
commit 96ff396e6e
2 changed files with 8 additions and 0 deletions
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