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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Nov 2021 07:09:48.0374 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 203f7b97-6ab9-4fb6-c1c4-08d9afe29118 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT034.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR1201MB0053 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 25, 2021 at 02:05:47PM +0800, Jason Wang wrote: > When VIRTIO_NET_F_MTU feature is not negotiated, we assume a very > large max_mtu. In this case, using small packet mode is not correct > since it may breaks the networking when MTU is grater than > ETH_DATA_LEN. > > To have a quick fix, simply enable the big packet mode when > VIRTIO_NET_F_MTU is not negotiated. We can do optimization on top. > > Reported-by: Eli Cohen > Cc: Eli Cohen > Signed-off-by: Jason Wang > --- > drivers/net/virtio_net.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 7c43bfc1ce44..83ae3ef5eb11 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3200,11 +3200,12 @@ static int virtnet_probe(struct virtio_device *vdev) > dev->mtu = mtu; > dev->max_mtu = mtu; > > - /* TODO: size buffers correctly in this case. */ > - if (dev->mtu > ETH_DATA_LEN) > - vi->big_packets = true; > } > > + /* TODO: size buffers correctly in this case. */ > + if (dev->max_mtu > ETH_DATA_LEN) > + vi->big_packets = true; > + If VIRTIO_NET_F_MTU is provided, then dev->max_mtu is going to equal ETH_DATA_LEN (will be set in ether_setup()) so I don't think it will set big_packets to true. > if (vi->any_header_sg) > dev->needed_headroom = vi->hdr_len; > > -- > 2.25.1 >