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

[Long Li <longli@microsoft.com>]

>Subject: [dpdk-dev] [PATCH] net/vdev_netvsc: handle removal of associated
>pci device
>
>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.
>
>Fixes: e7dc5d7becc5 ("net/vdev_netvsc: implement core functionality")
>Cc: matan@mellanox.com, stable@dpdk.org
>Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Reviewed-by: Long Li <longli@microsoft.com>

>---
> 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;
>+
>+	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