[PATCH] virNetDevMacVLanTapSetup: Work around older systems

[Michal Privoznik <mprivozn@xxxxxxxxxx>]

Some older systems, e.g. RHEL-6 do not have IFF_MULTI_QUEUE flag
which we use to enable multiqueue feature. Therefore one gets the
following compile error there:

  CC     util/libvirt_util_la-virnetdevmacvlan.lo
util/virnetdevmacvlan.c: In function 'virNetDevMacVLanTapSetup':
util/virnetdevmacvlan.c:338: error: 'IFF_MULTI_QUEUE' undeclared (first use in this function)
util/virnetdevmacvlan.c:338: error: (Each undeclared identifier is reported only once
util/virnetdevmacvlan.c:338: error: for each function it appears in.)
make[3]: *** [util/libvirt_util_la-virnetdevmacvlan.lo] Error 1

So, whenever user wants us to enable the feature on such systems,
we will just throw a runtime error instead.

Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
 src/util/virnetdevmacvlan.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/util/virnetdevmacvlan.c b/src/util/virnetdevmacvlan.c
index d8d1d90..28c9f22 100644
--- a/src/util/virnetdevmacvlan.c
+++ b/src/util/virnetdevmacvlan.c
@@ -307,49 +307,57 @@ static int
 virNetDevMacVLanTapSetup(int *tapfd, size_t tapfdSize, bool vnet_hdr, bool multiqueue)
 {
     unsigned int features;
     struct ifreq ifreq;
     short new_flags = 0;
     size_t i;
 
     for (i = 0; i < tapfdSize; i++) {
         memset(&ifreq, 0, sizeof(ifreq));
 
         if (ioctl(tapfd[i], TUNGETIFF, &ifreq) < 0) {
             virReportSystemError(errno, "%s",
                                  _("cannot get interface flags on macvtap tap"));
             return -1;
         }
 
         new_flags = ifreq.ifr_flags;
 
         if (vnet_hdr) {
             if (ioctl(tapfd[i], TUNGETFEATURES, &features) < 0) {
                 virReportSystemError(errno, "%s",
                                      _("cannot get feature flags on macvtap tap"));
                 return -1;
             }
             if (features & IFF_VNET_HDR)
                 new_flags |= IFF_VNET_HDR;
         } else {
             new_flags &= ~IFF_VNET_HDR;
         }
 
+#ifdef IFF_MULTI_QUEUE
         if (multiqueue)
             new_flags |= IFF_MULTI_QUEUE;
         else
             new_flags &= ~IFF_MULTI_QUEUE;
+#else
+        if (multiqueue) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("Multiqueue devices are not supported on this system"));
+            return -1;
+        }
+#endif
 
         if (new_flags != ifreq.ifr_flags) {
             ifreq.ifr_flags = new_flags;
             if (ioctl(tapfd[i], TUNSETIFF, &ifreq) < 0) {
                 virReportSystemError(errno, "%s",
                                      _("unable to set vnet or multiqueue flags on macvtap"));
                 return -1;
             }
         }
     }
 
     return 0;
 }
 
 
-- 
2.4.10

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