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Date: Tue, 30 Mar 2021 13:43:09 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Haiyang Zhang <haiyangz@...rosoft.com>,
linux-hyperv@...r.kernel.org, netdev@...r.kernel.org
Cc: haiyangz@...rosoft.com, kys@...rosoft.com, sthemmin@...rosoft.com,
olaf@...fle.de, davem@...emloft.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] hv_netvsc: Add error handling while switching
data path
Haiyang Zhang <haiyangz@...rosoft.com> writes:
> Add error handling in case of failure to send switching data path message
> to the host.
>
> Reported-by: Shachar Raindel <shacharr@...rosoft.com>
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
>
> ---
> drivers/net/hyperv/hyperv_net.h | 6 +++++-
> drivers/net/hyperv/netvsc.c | 35 +++++++++++++++++++++++++++++----
> drivers/net/hyperv/netvsc_drv.c | 18 +++++++++++------
> 3 files changed, 48 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index 59ac04a610ad..442c520ab8f3 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -269,7 +269,7 @@ int rndis_filter_receive(struct net_device *ndev,
> int rndis_filter_set_device_mac(struct netvsc_device *ndev,
> const char *mac);
>
> -void netvsc_switch_datapath(struct net_device *nv_dev, bool vf);
> +int netvsc_switch_datapath(struct net_device *nv_dev, bool vf);
>
> #define NVSP_INVALID_PROTOCOL_VERSION ((u32)0xFFFFFFFF)
>
> @@ -1718,4 +1718,8 @@ struct rndis_message {
> #define TRANSPORT_INFO_IPV6_TCP 0x10
> #define TRANSPORT_INFO_IPV6_UDP 0x20
>
> +#define RETRY_US_LO 5000
> +#define RETRY_US_HI 10000
> +#define RETRY_MAX 2000 /* >10 sec */
> +
> #endif /* _HYPERV_NET_H */
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 5bce24731502..9d07c9ce4be2 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -31,12 +31,13 @@
> * Switch the data path from the synthetic interface to the VF
> * interface.
> */
> -void netvsc_switch_datapath(struct net_device *ndev, bool vf)
> +int netvsc_switch_datapath(struct net_device *ndev, bool vf)
> {
> struct net_device_context *net_device_ctx = netdev_priv(ndev);
> struct hv_device *dev = net_device_ctx->device_ctx;
> struct netvsc_device *nv_dev = rtnl_dereference(net_device_ctx->nvdev);
> struct nvsp_message *init_pkt = &nv_dev->channel_init_pkt;
> + int ret, retry = 0;
>
> /* Block sending traffic to VF if it's about to be gone */
> if (!vf)
> @@ -51,15 +52,41 @@ void netvsc_switch_datapath(struct net_device *ndev, bool vf)
> init_pkt->msg.v4_msg.active_dp.active_datapath =
> NVSP_DATAPATH_SYNTHETIC;
>
> +again:
> trace_nvsp_send(ndev, init_pkt);
>
> - vmbus_sendpacket(dev->channel, init_pkt,
> + ret = vmbus_sendpacket(dev->channel, init_pkt,
> sizeof(struct nvsp_message),
> - (unsigned long)init_pkt,
> - VM_PKT_DATA_INBAND,
> + (unsigned long)init_pkt, VM_PKT_DATA_INBAND,
> VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> +
> + /* If failed to switch to/from VF, let data_path_is_vf stay false,
> + * so we use synthetic path to send data.
> + */
> + if (ret) {
> + if (ret != -EAGAIN) {
> + netdev_err(ndev,
> + "Unable to send sw datapath msg, err: %d\n",
> + ret);
> + return ret;
> + }
> +
> + if (retry++ < RETRY_MAX) {
> + usleep_range(RETRY_US_LO, RETRY_US_HI);
> + goto again;
> + } else {
> + netdev_err(
> + ndev,
> + "Retry failed to send sw datapath msg, err: %d\n",
> + ret);
err is always -EAGAIN here, right?
> + return ret;
> + }
Nitpicking: I think we can simplify the above a bit:
if (ret) {
if (ret == -EAGAIN && retry++ < RETRY_MAX) {
usleep_range(RETRY_US_LO, RETRY_US_HI);
goto again;
}
netdev_err(ndev, "Unable to send sw datapath msg, err: %d\n", ret);
return ret;
}
> + }
> +
> wait_for_completion(&nv_dev->channel_init_wait);
> net_device_ctx->data_path_is_vf = vf;
> +
> + return 0;
> }
>
> /* Worker to setup sub channels on initial setup
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index 97b5c9b60503..7349a70af083 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -38,9 +38,6 @@
> #include "hyperv_net.h"
>
> #define RING_SIZE_MIN 64
> -#define RETRY_US_LO 5000
> -#define RETRY_US_HI 10000
> -#define RETRY_MAX 2000 /* >10 sec */
>
> #define LINKCHANGE_INT (2 * HZ)
> #define VF_TAKEOVER_INT (HZ / 10)
> @@ -2402,6 +2399,7 @@ static int netvsc_vf_changed(struct net_device *vf_netdev, unsigned long event)
> struct netvsc_device *netvsc_dev;
> struct net_device *ndev;
> bool vf_is_up = false;
> + int ret;
>
> if (event != NETDEV_GOING_DOWN)
> vf_is_up = netif_running(vf_netdev);
> @@ -2418,9 +2416,17 @@ static int netvsc_vf_changed(struct net_device *vf_netdev, unsigned long event)
> if (net_device_ctx->data_path_is_vf == vf_is_up)
> return NOTIFY_OK;
>
> - netvsc_switch_datapath(ndev, vf_is_up);
> - netdev_info(ndev, "Data path switched %s VF: %s\n",
> - vf_is_up ? "to" : "from", vf_netdev->name);
> + ret = netvsc_switch_datapath(ndev, vf_is_up);
> +
> + if (ret) {
> + netdev_err(ndev,
> + "Data path failed to switch %s VF: %s, err: %d\n",
> + vf_is_up ? "to" : "from", vf_netdev->name, ret);
> + return NOTIFY_DONE;
> + } else {
> + netdev_info(ndev, "Data path switched %s VF: %s\n",
> + vf_is_up ? "to" : "from", vf_netdev->name);
> + }
>
> return NOTIFY_OK;
> }
--
Vitaly
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