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Patch "mlx4: Invoke softirqs after napi_reschedule" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Feb 15, 2017

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This is a note to let you know that I've just added the patch titled

mlx4: Invoke softirqs after napi_reschedule

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mlx4-invoke-softirqs-after-napi_reschedule.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Tue Feb 14 16:29:59 PST 2017

From: Benjamin Poirier <[email protected]>
Date: Mon, 6 Feb 2017 10:14:31 -0800
Subject: mlx4: Invoke softirqs after napi_reschedule

From: Benjamin Poirier <[email protected]>

[ Upstream commit bd4ce941c8d5b862b2f83364be5dbe8fc8ab48f8 ]

mlx4 may schedule napi from a workqueue. Afterwards, softirqs are not run in a deterministic time frame and the following message may be logged:
NOHZ: local_softirq_pending 08

The problem is the same as what was described in commit ec13ee80145c ("virtio_net: invoke softirqs after __napi_schedule") and this patch applies the same fix to mlx4.

Fixes 07841f9d94c1 ("net/mlx4_en: Schedule napi when RX buffers allocation fails")
Cc Eric Dumazet <[email protected]>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
drivers/net/ethernet/mellanox/mlx4/en_rx.c +4 -1
@@ -502,8 +502,11 @@ void mlx4_en_recover_from_oom(struct mlx
 		return;
 
 	for (ring = 0; ring < priv->rx_ring_num; ring++) {
-		if (mlx4_en_is_ring_empty(priv->rx_ring[ring]))
+		if (mlx4_en_is_ring_empty(priv->rx_ring[ring])) {
+			local_bh_disable();
 			napi_reschedule(&priv->rx_cq[ring]->napi);
+			local_bh_enable();
+		}
 	}
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/mlx4-invoke-softirqs-after-napi_reschedule.patch