Re: [Intel-wired-lan] [PATCH net] iavf: fix deadlock in reset handling

[Petr Oros <poros@redhat.com>]

On 2/3/26 02:00, Jacob Keller wrote:
>
>
> On 2/2/2026 3:58 PM, Jakub Kicinski wrote:
>> On Mon,  2 Feb 2026 09:48:20 +0100 Petr Oros wrote:
>>> +    netdev_unlock(netdev);
>>> +    ret = wait_event_interruptible_timeout(adapter->reset_waitqueue,
>>> + !iavf_is_reset_in_progress(adapter),
>>> +                           msecs_to_jiffies(5000));
>>> +    netdev_lock(netdev);
>>
>> Dropping locks taken by the core around the driver callback
>> is obviously unacceptable. SMH.
>
> Right. It seems like the correct fix is to either a) have reset take 
> and hold the netdev lock (now that its distinct from the global RTNL 
> lock) or b) refactor reset so that it can defer any of the netdev 
> related stuff somehow.
>
I modeled this after the existing pattern in iavf_close() (ndo_stop), 
which also temporarily releases the netdev instance lock taken by the 
core to wait for an async operation to complete:

static int iavf_close(struct net_device *netdev)
{
         netdev_assert_locked(netdev);
         ...
         iavf_down(adapter);
         iavf_change_state(adapter, __IAVF_DOWN_PENDING);
         iavf_free_traffic_irqs(adapter);

         netdev_unlock(netdev);

         status = wait_event_timeout(adapter->down_waitqueue,
                                     adapter->state == __IAVF_DOWN,
                                     msecs_to_jiffies(500));
         if (!status)
                 netdev_warn(netdev, "Device resources not yet released\n");
         netdev_lock(netdev);
         ...
}

This was introduced by commit 120f28a6f314fe ("iavf: get rid of the crit 
lock"), and ndo_stop is called with netdev instance lock held by the 
core just like ndo_change_mtu is. Could you clarify why the 
unlock-wait-lock pattern is acceptable in ndo_stop but not here?