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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Emil Tantilov <emil.s.tantilov@intel.com>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Przemek Kitszel <przemyslaw.kitszel@intel.com>,
	Alan Brady <alan.brady@intel.com>,
	Simon Horman <horms@kernel.org>,
	Krishneil Singh <krishneil.k.singh@intel.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.7 28/61] idpf: disable local BH when scheduling napi for marker packets
Date: Wed, 13 Mar 2024 12:32:03 -0400
Message-ID: <20240313163236.613880-29-sashal@kernel.org>
In-Reply-To: <20240313163236.613880-1-sashal@kernel.org>
References: <20240313163236.613880-1-sashal@kernel.org>
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From: Emil Tantilov <emil.s.tantilov@intel.com>

[ Upstream commit 330068589389ccae3452db15ecacc3e147ac9c1c ]

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 when disabling local BH before calling napi_schedule:
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@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Alan Brady <alan.brady@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 2c1b051fdc0d4..b0c52f17848f6 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