[libvirt] [PATCH] util: generate correct macvtap name

[Shanzhi Yu]

in commit 370608b, bitmap of in-used macvtap devices was introduced.
if there is already macvtap device created not by libvirt,
virNetDevMacVLanCreateWithVPortProfile will failed after try
MACVLAN_MAX_ID times call virNetDevMacVLanReleaseID

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1321546

Signed-off-by: Shanzhi Yu <shyu at redhat.com>
---
 src/util/virnetdevmacvlan.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/util/virnetdevmacvlan.c b/src/util/virnetdevmacvlan.c
index 2409113..973363e 100644
--- a/src/util/virnetdevmacvlan.c
+++ b/src/util/virnetdevmacvlan.c
@@ -988,7 +988,8 @@ virNetDevMacVLanCreateWithVPortProfile(const char *ifnameRequested,
         MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX;
     const char *pattern = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
         MACVTAP_NAME_PATTERN : MACVLAN_NAME_PATTERN;
-    int rc, reservedID = -1;
+    int rc = -1;
+    int reservedID = 0;
     char ifname[IFNAMSIZ];
     int retries, do_retry = 0;
     uint32_t macvtapMode;
@@ -1072,16 +1073,17 @@ virNetDevMacVLanCreateWithVPortProfile(const char *ifnameRequested,
     retries = MACVLAN_MAX_ID;
     while (!ifnameCreated && retries) {
         virMutexLock(&virNetDevMacVLanCreateMutex);
-        reservedID = virNetDevMacVLanReserveID(reservedID, flags, false, true);
-        if (reservedID < 0) {
-            virMutexUnlock(&virNetDevMacVLanCreateMutex);
-            return -1;
-        }
         snprintf(ifname, sizeof(ifname), pattern, reservedID);
         rc = virNetDevMacVLanCreate(ifname, type, macaddress, linkdev,
                                     macvtapMode, &do_retry);
         if (rc < 0) {
-            virNetDevMacVLanReleaseID(reservedID, flags);
+            reservedID++;
+            reservedID = virNetDevMacVLanReserveID(reservedID, flags, false, true);
+            if (reservedID < 0) {
+                virMutexUnlock(&virNetDevMacVLanCreateMutex);
+                return -1;
+            }
+
             virMutexUnlock(&virNetDevMacVLanCreateMutex);
             if (!do_retry)
                 return -1;
-- 
1.8.3.1