| Message ID | 1415748472-27463-1-git-send-email-haiyangz@microsoft.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Haiyang Zhang <haiyangz@microsoft.com> Date: Tue, 11 Nov 2014 15:27:52 -0800 > - if (mtu < 68 || mtu > limit) > + if (mtu < ETH_DATA_LEN || mtu > limit) > return -EINVAL; This is not correct. The test is against the minimally supported MTU, which should be 68 not ETH_DATA_LEN which is 1500. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Wednesday, November 12, 2014 2:47 PM > To: Haiyang Zhang > Cc: netdev@vger.kernel.org; KY Srinivasan; olaf@aepfle.de; > jasowang@redhat.com; linux-kernel@vger.kernel.org; driverdev- > devel@linuxdriverproject.org > Subject: Re: [PATCH net-next] hyperv: Add processing of MTU reduced by > the host > > From: Haiyang Zhang <haiyangz@microsoft.com> > Date: Tue, 11 Nov 2014 15:27:52 -0800 > > > - if (mtu < 68 || mtu > limit) > > + if (mtu < ETH_DATA_LEN || mtu > limit) > > return -EINVAL; > > This is not correct. > > The test is against the minimally supported MTU, which should > be 68 not ETH_DATA_LEN which is 1500. The Hyper-V host doesn't support MTU below 1500. If we try setting MTU to a value < 1500, the host will use 1500 automatically and return 1500 in the RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE query and guest will also use it. That's why I set the lower limit to ETH_DATA_LEN. Are you suggesting that we keep the 68 as the lower limit, and let the host auto-reset it to 1500 when we trying to set an MTU < 1500? Thanks, - Haiyang -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Haiyang Zhang <haiyangz@microsoft.com> Date: Wed, 12 Nov 2014 20:02:11 +0000 > The Hyper-V host doesn't support MTU below 1500. If we try setting MTU to a > value < 1500, the host will use 1500 automatically and return 1500 in the > RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE query and guest will also use it. That's > why I set the lower limit to ETH_DATA_LEN. > > Are you suggesting that we keep the 68 as the lower limit, and let the host > auto-reset it to 1500 when we trying to set an MTU < 1500? Then you need to add a comment, because without any information or context that change looks wrong. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Wednesday, November 12, 2014 3:04 PM > To: Haiyang Zhang > Cc: netdev@vger.kernel.org; KY Srinivasan; olaf@aepfle.de; > jasowang@redhat.com; linux-kernel@vger.kernel.org; driverdev- > devel@linuxdriverproject.org > Subject: Re: [PATCH net-next] hyperv: Add processing of MTU reduced by > the host > > From: Haiyang Zhang <haiyangz@microsoft.com> > Date: Wed, 12 Nov 2014 20:02:11 +0000 > > > The Hyper-V host doesn't support MTU below 1500. If we try setting MTU > to a > > value < 1500, the host will use 1500 automatically and return 1500 in > the > > RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE query and guest will also use it. > That's > > why I set the lower limit to ETH_DATA_LEN. > > > > Are you suggesting that we keep the 68 as the lower limit, and let the > host > > auto-reset it to 1500 when we trying to set an MTU < 1500? > > Then you need to add a comment, because without any information or > context that change looks wrong. I will add a comment. Thanks, - Haiyang -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index 7d76c95..6b46311 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -440,7 +440,8 @@ static int negotiate_nvsp_ver(struct hv_device *device, /* NVSPv2 only: Send NDIS config */ memset(init_packet, 0, sizeof(struct nvsp_message)); init_packet->hdr.msg_type = NVSP_MSG2_TYPE_SEND_NDIS_CONFIG; - init_packet->msg.v2_msg.send_ndis_config.mtu = net_device->ndev->mtu; + init_packet->msg.v2_msg.send_ndis_config.mtu = net_device->ndev->mtu + + ETH_HLEN; init_packet->msg.v2_msg.send_ndis_config.capability.ieee8021q = 1; ret = vmbus_sendpacket(device->channel, init_packet, diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 3295e4e..b689f96 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -699,9 +699,9 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu) return -ENODEV; if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2) - limit = NETVSC_MTU; + limit = NETVSC_MTU - ETH_HLEN; - if (mtu < 68 || mtu > limit) + if (mtu < ETH_DATA_LEN || mtu > limit) return -EINVAL; nvdev->start_remove = true; diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c index ccce6f2..7b2c5d1 100644 --- a/drivers/net/hyperv/rndis_filter.c +++ b/drivers/net/hyperv/rndis_filter.c @@ -998,6 +998,7 @@ int rndis_filter_device_add(struct hv_device *dev, int t; struct ndis_recv_scale_cap rsscap; u32 rsscap_size = sizeof(struct ndis_recv_scale_cap); + u32 mtu, size; rndis_device = get_rndis_device(); if (!rndis_device) @@ -1029,6 +1030,14 @@ int rndis_filter_device_add(struct hv_device *dev, return ret; } + /* Get the MTU from the host */ + size = sizeof(u32); + ret = rndis_filter_query_device(rndis_device, + RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE, + &mtu, &size); + if (ret == 0 && size == sizeof(u32)) + net_device->ndev->mtu = mtu; + /* Get the mac address */ ret = rndis_filter_query_device_mac(rndis_device); if (ret != 0) {
If the host uses packet encapsulation feature, the MTU may be reduced by the host due to headroom reservation for encapsulation. This patch handles this new MTU value. Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> --- drivers/net/hyperv/netvsc.c | 3 ++- drivers/net/hyperv/netvsc_drv.c | 4 ++-- drivers/net/hyperv/rndis_filter.c | 9 +++++++++ 3 files changed, 13 insertions(+), 3 deletions(-)