Re: [PATCH] virtio-net: disable delayed refill when setting up xdp

[Bui Quang Minh <minhquangbui99@gmail.com>]

On 4/3/25 17:43, Bui Quang Minh wrote:
> On 4/2/25 12:42, Bui Quang Minh wrote:
>> When setting up XDP for a running interface, we call napi_disable() on
>> the receive queue's napi. In delayed refill_work, it also calls
>> napi_disable() on the receive queue's napi. This can leads to deadlock
>> when napi_disable() is called on an already disabled napi. This commit
>> fixes this by disabling future and cancelling all inflight delayed
>> refill works before calling napi_disabled() in virtnet_xdp_set.
>>
>> Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set")
>> Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
>> ---
>>   drivers/net/virtio_net.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 7e4617216a4b..33406d59efe2 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -5956,6 +5956,15 @@ static int virtnet_xdp_set(struct net_device 
>> *dev, struct bpf_prog *prog,
>>       if (!prog && !old_prog)
>>           return 0;
>>   +    /*
>> +     * Make sure refill_work does not run concurrently to
>> +     * avoid napi_disable race which leads to deadlock.
>> +     */
>> +    if (netif_running(dev)) {
>> +        disable_delayed_refill(vi);
>> +        cancel_delayed_work_sync(&vi->refill);
>> +    }
>> +
>>       if (prog)
>>           bpf_prog_add(prog, vi->max_queue_pairs - 1);
>>   @@ -6004,6 +6013,8 @@ static int virtnet_xdp_set(struct net_device 
>> *dev, struct bpf_prog *prog,
>>               virtnet_napi_tx_enable(&vi->sq[i]);
>>           }
>>       }
>> +    if (netif_running(dev))
>> +        enable_delayed_refill(vi);
> While doing some testing, it look likes that we must call 
> try_fill_recv to resume the rx path. I'll do more testing and send a 
> new v2 patch.

I've sent a new patch here: 
https://lore.kernel.org/virtualization/20250404093903.37416-1-minhquangbui99@gmail.com/T/#u. 
As the commit title has changed a little bit, I don't use v2 tag.

Thank you,
Quang Minh.