Re: [Intel-wired-lan] [PATCH net] igc: remove napi_synchronize() in igc_down()

On 13/07/2026 12:42, Maciej Fijalkowski wrote:
> On Sun, Jul 12, 2026 at 02:22:42PM +0100, David Carlier wrote:
>> When an AF_XDP zero-copy application is killed abruptly, the XSK pool is
>> torn down but NAPI keeps polling. igc_clean_rx_irq_zc() then returns the
>> full budget on every poll, so napi_complete_done() never clears
>> NAPI_STATE_SCHED.
>>
>> igc_down() calls napi_synchronize() before napi_disable(), so it spins
>> forever waiting for that bit and the interface never goes down. Drop the
>> napi_synchronize() and let napi_disable() do the job -- it sets
>> NAPI_STATE_DISABLE, which forces the stuck poll to complete. Reorder it
>> ahead of igc_set_queue_napi() so the NAPI mapping is cleared only after
>> polling has stopped, matching the recent igb fix b1e067240379.
>>
>> Fixes: fc9df2a0b520 ("igc: Enable RX via AF_XDP zero-copy")
>> Suggested-by: Maciej Fijalkowski <[email protected]>
>> Cc: [email protected]
>> Signed-off-by: David Carlier <[email protected]>
> 
> Reviewed-by: Maciej Fijalkowski <[email protected]>
> 
> This is a mirror of what Alex Dvoretsky did on igb, correct? Did you
> reproduce the same issue on your side or is it a blind shot at this
> driver?
> 
> Regardless, I think it's a correct thing to do, but some clarification
> would be nice.
> 
>> ---
>>   drivers/net/ethernet/intel/igc/igc_main.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
>> index 2c9e2dfd8499..b3883a5a7d7a 100644
>> --- a/drivers/net/ethernet/intel/igc/igc_main.c
>> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
>> @@ -5352,9 +5352,8 @@ void igc_down(struct igc_adapter *adapter)
>>   
>>   	for (i = 0; i < adapter->num_q_vectors; i++) {
>>   		if (adapter->q_vector[i]) {
>> -			napi_synchronize(&adapter->q_vector[i]->napi);
>> -			igc_set_queue_napi(adapter, i, NULL);
>>   			napi_disable(&adapter->q_vector[i]->napi);
>> +			igc_set_queue_napi(adapter, i, NULL);
>>   		}
>>   	}
>>   
>> -- 
>> 2.53.0
>>
Reviewed-by: Dima Ruinskiy <[email protected]>