Re: [dpdk-dev] [PATCH] net/vdev_netvsc: handle removal of associated pci device

[Matan Azrad <matan@nvidia.com>]

Hi Stephen

From: Stephen Hemminger:
> The vdev_netvsc was not detecting when the associated PCI device
> (SRIOV) was removed. Because of that it would keep feeding the same
> (removed) device to failsafe PMD which would then unsuccessfully try and
> probe for it.
> 
> Change to use a mark/sweep method to detect that PCI device was
> removed, and also only tell failsafe about new PCI devices.
> Vdev_netvsc does not have to keep stuffing the pipe with the same already
> existing PCI device.

As I know, the vdev_netvsc driver doesn't call to failsafe if the PCI device is not detected by the readlink command(considered as removed)...
Am I missing something?

>
> Fixes: e7dc5d7becc5 ("net/vdev_netvsc: implement core functionality")
> Cc: matan@mellanox.com, stable@dpdk.org
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  drivers/net/vdev_netvsc/vdev_netvsc.c | 39 +++++++++++++++++++++++-
> ---
>  1 file changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/vdev_netvsc/vdev_netvsc.c
> b/drivers/net/vdev_netvsc/vdev_netvsc.c
> index 1ecb0b3e6a34..80a3158012ce 100644
> --- a/drivers/net/vdev_netvsc/vdev_netvsc.c
> +++ b/drivers/net/vdev_netvsc/vdev_netvsc.c
> @@ -66,6 +66,7 @@ struct vdev_netvsc_ctx {
>         char devargs[256];                 /**< Fail-safe device arguments. */
>         char if_name[IF_NAMESIZE];         /**< NetVSC netdevice name. */
>         unsigned int if_index;             /**< NetVSC netdevice index. */
> +       int pci_found;                     /**< Device detection */
>         struct rte_ether_addr if_addr;     /**< NetVSC MAC address. */
>         int pipe[2];                       /**< Fail-safe communication pipe. */
>         char yield[256];                   /**< PCI sub-device arguments. */
> @@ -405,11 +406,18 @@ vdev_netvsc_device_probe(const struct
> if_nameindex *iface,
>         len = strlen(addr);
>         if (!len)
>                 return 0;
> +

The file code convention is to use blank lines in blocks only after variables declarations.

> +       ctx->pci_found = 1;
> +
> +       /* Skip if this is same device already sent to failsafe */
> +       if (strcmp(addr, ctx->yield) == 0)
> +               return 0;
> +
> +       DRV_LOG(DEBUG, "associating PCI device \"%s\" with NetVSC"
> +               " interface \"%s\" (index %u)", addr, ctx->if_name,
> +               ctx->if_index);
> +
>         /* Send PCI device argument to fail-safe PMD instance. */
> -       if (strcmp(addr, ctx->yield))
> -               DRV_LOG(DEBUG, "associating PCI device \"%s\" with NetVSC"
> -                       " interface \"%s\" (index %u)", addr, ctx->if_name,
> -                       ctx->if_index);
>         memmove(buf, addr, len + 1);
>         addr = buf;
>         buf[len] = '\n';
> @@ -452,12 +460,33 @@ vdev_netvsc_alarm(__rte_unused void *arg)
>         struct vdev_netvsc_ctx *ctx;
>         int ret;
> 
> +       /* 1st pass: clear PCI flag on all devices */
> +       LIST_FOREACH(ctx, &vdev_netvsc_ctx_list, entry) {
> +               ctx->pci_found = 0;
> +       }
> +
> +       /* 2nd pass: scan all system devices to look for changes to this
> + device */
>         LIST_FOREACH(ctx, &vdev_netvsc_ctx_list, entry) {
>                 ret = vdev_netvsc_foreach_iface(vdev_netvsc_device_probe, 0,
>                       ctx);
> -               if (ret < 0)
> +
> +               if (ret < 0) {
> +                       DRV_LOG(NOTICE, "can not scan devices for %s\n",
> +                               ctx->if_name);
>                         break;
> +               }
>         }
> +
> +       /* 3rd pass: detect PCI removal */
> +       LIST_FOREACH(ctx, &vdev_netvsc_ctx_list, entry) {
> +               if (!ctx->pci_found && ctx->yield[0]) {
> +                       DRV_LOG(DEBUG, "disassociating PCI device \"%s\" from
> NetVSC"
> +                               " interface \"%s\" (index %u)", ctx->yield, ctx->if_name,
> +                               ctx->if_index);
> +                       ctx->yield[0] = '\0';
> +               }
> +       }
> +
>         if (!vdev_netvsc_ctx_count)
>                 return;
>         ret = rte_eal_alarm_set(VDEV_NETVSC_PROBE_MS * 1000,
> --
> 2.27.0