[PATCH 6.1 248/303] igc: remove napi_synchronize() in igc_down()

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Carlier <[email protected]>

[ Upstream commit 5ffab5b9589c50e4cfc0cf36ffd76c89422d4019 ]

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]>
Reviewed-by: Dima Ruinskiy <[email protected]>
Tested-by: Moriya Kadosh <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/net/ethernet/intel/igc/igc_main.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5034,7 +5034,6 @@ void igc_down(struct igc_adapter *adapte
 
 	for (i = 0; i < adapter->num_q_vectors; i++) {
 		if (adapter->q_vector[i]) {
-			napi_synchronize(&adapter->q_vector[i]->napi);
 			napi_disable(&adapter->q_vector[i]->napi);
 		}
 	}