FAILED: patch "[PATCH] igc: remove napi_synchronize() in igc_down()" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 5ffab5b9589c50e4cfc0cf36ffd76c89422d4019
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026080522-spinster-tricking-40ab@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5ffab5b9589c50e4cfc0cf36ffd76c89422d4019 Mon Sep 17 00:00:00 2001
From: David Carlier <[email protected]>
Date: Sun, 12 Jul 2026 14:22:42 +0100
Subject: [PATCH] igc: remove napi_synchronize() in igc_down()

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]>

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);
 		}
 	}