netdev - [PATCH 1/1 iwl-net] idpf: disable local BH when scheduling napi for marker packets

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Date: Wed,  7 Feb 2024 16:42:43 -0800
From: Alan Brady <alan.brady@...el.com>
To: intel-wired-lan@...ts.osuosl.org
Cc: netdev@...r.kernel.org,
	Emil Tantilov <emil.s.tantilov@...el.com>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Alan Brady <alan.brady@...el.com>
Subject: [PATCH 1/1 iwl-net] idpf: disable local BH when scheduling napi for marker packets

From: Emil Tantilov <emil.s.tantilov@...el.com>

Fix softirq's not being handled during napi_schedule() call when
receiving marker packets for queue disable by disabling local bottom
half.

The issue can be seen on ifdown:
NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #08!!!

Using ftrace to catch the failing scenario:
ifconfig   [003] d.... 22739.830624: softirq_raise: vec=3 [action=NET_RX]
<idle>-0   [003] ..s.. 22739.831357: softirq_entry: vec=3 [action=NET_RX]

No interrupt and CPU is idle.

After the patch, with BH locks:
ifconfig   [003] d.... 22993.928336: softirq_raise: vec=3 [action=NET_RX]
ifconfig   [003] ..s1. 22993.928337: softirq_entry: vec=3 [action=NET_RX]

Fixes: c2d548cad150 ("idpf: add TX splitq napi poll support")
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@...el.com>
Signed-off-by: Alan Brady <alan.brady@...el.com>
---
 drivers/net/ethernet/intel/idpf/idpf_virtchnl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
index d0cdd63b3d5b..390977a76de2 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
@@ -2087,8 +2087,10 @@ int idpf_send_disable_queues_msg(struct idpf_vport *vport)
 		set_bit(__IDPF_Q_POLL_MODE, vport->txqs[i]->flags);
 
 	/* schedule the napi to receive all the marker packets */
+	local_bh_disable();
 	for (i = 0; i < vport->num_q_vectors; i++)
 		napi_schedule(&vport->q_vectors[i].napi);
+	local_bh_enable();
 
 	return idpf_wait_for_marker_event(vport);
 }
-- 
2.43.0