> -----Original Message-----
> From: Vitaly Kuznetsov <vkuzn...@redhat.com>
> Sent: Tuesday, March 30, 2021 7:43 AM
> To: Haiyang Zhang <haiya...@microsoft.com>; linux-
> hyp...@vger.kernel.org; net...@vger.kernel.org
> Cc: Haiyang Zhang <haiya...@microsoft.com>; KY Srinivasan
> <k...@microsoft.com>; Stephen Hemminger <sthem...@microsoft.com>;
> o...@aepfle.de; da...@davemloft.net; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH net-next] hv_netvsc: Add error handling while switching
> data path
>
> Haiyang Zhang <haiya...@microsoft.com> writes:
>
> > Add error handling in case of failure to send switching data path message
> > to the host.
> >
> > Reported-by: Shachar Raindel <shach...@microsoft.com>
> > Signed-off-by: Haiyang Zhang <haiya...@microsoft.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;
> }
>
Yes this looks cleaner.
Thanks,
Haiyang
