[libvirt PATCH] util: don't log error if SRIOV PF has no associated netdev

[Michal Privoznik]

On 2/24/21 4:35 AM, Laine Stump wrote:
> Some SRIOV PFs don't have a netdev associated with them (the spec
> apparently doesn't require it). In most cases when libvirt is dealing
> with an SRIOV VF, that VF must have a PF, and the PF *must* have an
> associated netdev (the only way to set the MAC address of a VF is by
> sending a netlink message to the netdev of that VF's PF). But there
> are times when we don't need for the PF to have a netdev; in
> particular, when we're just getting the Switchdev Features for a VF,
> we don't need the PF netdev - the netdev of the VF (apparently) works
> just as well.
> 
> Commit 6452e2f5 (libvirt 5.1.0) *kind of* made libvirt work around PFs
> with no netdevs in this case - if virNetDevGetPhysicalFunction
> returned an error when setting up to retrieve Switchdev feature info,
> it would ignore the error, and then check if the PF netdev name was
> NULL and, if so it would reset the error object and continue on rather
> than returning early with a failure. The problem is that by the time
> this special handling occured, the error message about missing netdev
> had already been logged, which was harmless to proper operation, but
> confused the user.
> 
> Fortunately there are only 2 users of virNetDevGetPhysicalFunction, so
> it is easy to redefine it's API to state that a missing netdev name is
> *not* an error - in that case it will still return success, but the
> caller must be prepared for the PF netdev name to be NULL. After
> making this change, we can modify the two callers to behave properly
> with the new semantics (for one of the callers it *is* still an error,
> so the error message is moved there, but for the other it is okay to
> continue), and our spurious error messages are a thing of the past.
> 
> Resolves: https://bugzilla.redhat.com/1924616
> Fixes: 6452e2f5e1837bd753ee465e6607ed3c4f62b815
> Signed-off-by: Laine Stump <laine at redhat.com>
> ---
>   src/util/virnetdev.c | 31 +++++++++++++++----------------
>   1 file changed, 15 insertions(+), 16 deletions(-)

Reviewed-by: Michal Privoznik <mprivozn at redhat.com>

Michal