[PATCH v2] virnetdevveth: Do report error if creating veth fails

[Martin Kletzander]

On Thu, Dec 02, 2021 at 02:41:47PM +0100, Michal Privoznik wrote:
>For some weird reason we are ignoring errors when creating veth
>pair that netlink reports. This affects the LXC driver which
>creates interfaces for container in
>virLXCProcessSetupInterfaces(). If creating a veth pair fails, no
>error is reported and the control jumps onto cleanup label where
>some cryptic error message is reported instead (something about
>inability to remove veth pair).
>
>Let's report error that netlink returned - it's probably the most
>accurate reason anyways.
>
>Resolves: https://gitlab.com/libvirt/libvirt/-/issues/225
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>

Reviewed-by: Martin Kletzander <mkletzan at redhat.com>

>---
>
>v2 of:
>
>https://listman.redhat.com/archives/libvir-list/2021-December/msg00016.html
>
>diff to v1:
>- Report error only if it wasn't already reported (error == 0)
>
> src/util/virnetdevveth.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
>diff --git a/src/util/virnetdevveth.c b/src/util/virnetdevveth.c
>index 7133af44a2..b580e105ac 100644
>--- a/src/util/virnetdevveth.c
>+++ b/src/util/virnetdevveth.c
>@@ -38,10 +38,19 @@ VIR_LOG_INIT("util.netdevveth");
> static int
> virNetDevVethCreateInternal(const char *veth1, const char *veth2)
> {
>-    int status;     /* Just ignore it */
>+    int error = 0;
>     virNetlinkNewLinkData data = { .veth_peer = veth2 };
>
>-    return virNetlinkNewLink(veth1, "veth", &data, &status);
>+    if (virNetlinkNewLink(veth1, "veth", &data, &error) < 0) {
>+        if (error != 0) {
>+            virReportSystemError(-error,
>+                                 _("unable to create %s <-> %s veth pair"),
>+                                 veth1, veth2);
>+        }
>+        return -1;
>+    }
>+
>+    return 0;
> }
>
> static int
>-- 
>2.32.0
>
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