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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kimitoshi Takahashi <ktaka@nii.ac.jp>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.16 53/81] virtio-net: add missing virtqueue kick when flushing packets
Date:   Fri, 27 Apr 2018 15:58:55 +0200
Message-Id: <20180427135746.321343844@linuxfoundation.org>
In-Reply-To: <20180427135743.216853156@linuxfoundation.org>
References: <20180427135743.216853156@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

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

From: Jason Wang <jasowang@redhat.com>


[ Upstream commit 9267c430c6b6f4c0120e3c6bb847313d633f02a6 ]

We tends to batch submitting packets during XDP_TX. This requires to
kick virtqueue after a batch, we tried to do it through
xdp_do_flush_map() which only makes sense for devmap not XDP_TX. So
explicitly kick the virtqueue in this case.

Reported-by: Kimitoshi Takahashi <ktaka@nii.ac.jp>
Tested-by: Kimitoshi Takahashi <ktaka@nii.ac.jp>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Fixes: 186b3c998c50 ("virtio-net: support XDP_REDIRECT")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/virtio_net.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1269,7 +1269,9 @@ static int virtnet_poll(struct napi_stru
 {
 	struct receive_queue *rq =
 		container_of(napi, struct receive_queue, napi);
-	unsigned int received;
+	struct virtnet_info *vi = rq->vq->vdev->priv;
+	struct send_queue *sq;
+	unsigned int received, qp;
 	bool xdp_xmit = false;
 
 	virtnet_poll_cleantx(rq);
@@ -1280,8 +1282,13 @@ static int virtnet_poll(struct napi_stru
 	if (received < budget)
 		virtqueue_napi_complete(napi, rq->vq, received);
 
-	if (xdp_xmit)
+	if (xdp_xmit) {
+		qp = vi->curr_queue_pairs - vi->xdp_queue_pairs +
+		     smp_processor_id();
+		sq = &vi->sq[qp];
+		virtqueue_kick(sq->vq);
 		xdp_do_flush_map();
+	}
 
 	return received;
 }