Re: [libvirt] [PATCH 4/6] virNetDevMacVLanTapSetup: Rework to support multiple FDs

On 12/04/2015 07:31 AM, Michal Privoznik wrote: > So, for the multiqueue on macvtaps we are going to need to open > the device multiple times. Currently, this is not supported. > Rework the function, so that upper layers can be reworked too. Either merge 3 & 4 together, or change the log message (I'm okay with multiple functions at the same level being changed in the same patch). > > Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; > --- > src/util/virnetdevmacvlan.c | 66 > ++++++++++++++++++++++++--------------------- > 1 file changed, 35 insertions(+), 31 deletions(-) > > diff --git a/src/util/virnetdevmacvlan.c b/src/util/virnetdevmacvlan.c > index d20990b..f7a7d72 100644 > --- a/src/util/virnetdevmacvlan.c > +++ b/src/util/virnetdevmacvlan.c > @@ -302,10 +302,9 @@ virNetDevMacVLanTapOpen(const char *ifname, > /** > * virNetDevMacVLanTapSetup: > - * @tapfd: file descriptor of the macvtap tap > - * @vnet_hdr: 1 to enable IFF_VNET_HDR, 0 to disable it > - * > - * Returns 0 on success, -1 in case of fatal error, error code > otherwise. > + * @tapfd: array of file descriptors of the macvtap tap > + * @tapfdSize: number of file descriptors in @tapfd > + * @vnet_hdr: whether to enable or disable IFF_VNET_HDR > * > * Turn the IFF_VNET_HDR flag, if requested and available, make sure > * it's off in the other cases. > @@ -313,47 +312,52 @@ virNetDevMacVLanTapOpen(const char *ifname, > * be turned off for some reason. This is reported with -1. Other fatal > * error is not being able to read the interface flags. In that case > the > * macvtap device should not be used. > + * Comparing this to the VNET_HDR stuff for tap devices, I see that in that case lack of support for VNET_HDR isn't fatal - it simply isn't set. My guess is that VNET_HDR support was probably added prior to macvtap, so that it's always there if we're doing macvtap, but I don't know for sure. (I'm just wondering if maybe there's some way code could be shared between the two to reduce maintenance). The other difference is that IFF_MULTI_QUEUE is set on each fd for a tap device. Is this also needed for macvtap?