linux-kernel - [PATCH 3.18 009/145] mlx4: Invoke softirqs after napi

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Date:   Sun, 16 Apr 2017 12:48:22 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <eric.dumazet@...il.com>,
        Benjamin Poirier <bpoirier@...e.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.18 009/145] mlx4: Invoke softirqs after napi_reschedule

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

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

From: Benjamin Poirier <bpoirier@...e.com>


[ 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 <eric.dumazet@...il.com>
Signed-off-by: Benjamin Poirier <bpoirier@...e.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx4/en_rx.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -501,8 +501,11 @@ 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();
+		}
 	}
 }