network: remove the virDomainNetBandwidthChangeAllowed callback

The current qemu driver code for changing bandwidth on a NIC first asks
the network driver if the change is supported, then changes the
bandwidth on the VIF, and then tells the network driver to update the
bandwidth on the bridge.

This is potentially racing if a parallel API call causes the network
driver to allocate bandwidth on the bridge between the check and the
update phases.

Change the code to just try to apply the network bridge update
immediately and rollback at the end if something failed.
Reviewed-by: NLaine Stump <laine@laine.org>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/conf/domain_conf.c

@@ -30670,7 +30670,6 @@ virDomainNetDefActualToNetworkPort(virDomainDefPtr dom,
 static virDomainNetAllocateActualDeviceImpl netAllocate;
 static virDomainNetNotifyActualDeviceImpl netNotify;
 static virDomainNetReleaseActualDeviceImpl netRelease;
-static virDomainNetBandwidthChangeAllowedImpl netBandwidthChangeAllowed;
 static virDomainNetBandwidthUpdateImpl netBandwidthUpdate;
 
 
@@ -30678,13 +30677,11 @@ void
 virDomainNetSetDeviceImpl(virDomainNetAllocateActualDeviceImpl allocate,
                           virDomainNetNotifyActualDeviceImpl notify,
                           virDomainNetReleaseActualDeviceImpl release,
-                          virDomainNetBandwidthChangeAllowedImpl bandwidthChangeAllowed,
                           virDomainNetBandwidthUpdateImpl bandwidthUpdate)
 {
     netAllocate = allocate;
     netNotify = notify;
     netRelease = release;
-    netBandwidthChangeAllowed = bandwidthChangeAllowed;
     netBandwidthUpdate = bandwidthUpdate;
 }
 
@@ -30767,18 +30764,6 @@ virDomainNetReleaseActualDevice(virConnectPtr conn,
     return ret;
 }
 
-bool
-virDomainNetBandwidthChangeAllowed(virDomainNetDefPtr iface,
-                                   virNetDevBandwidthPtr newBandwidth)
-{
-    if (!netBandwidthChangeAllowed) {
-        virReportError(VIR_ERR_NO_SUPPORT, "%s",
-                       _("Virtual networking driver is not available"));
-        return -1;
-    }
-
-    return netBandwidthChangeAllowed(iface, newBandwidth);
-}
 
 int
 virDomainNetBandwidthUpdate(virDomainNetDefPtr iface,

src/conf/domain_conf.h

@@ -3584,10 +3584,6 @@ typedef int
                                        virDomainDefPtr dom,
                                        virDomainNetDefPtr iface);
 
-typedef bool
-(*virDomainNetBandwidthChangeAllowedImpl)(virDomainNetDefPtr iface,
-                                          virNetDevBandwidthPtr newBandwidth);
-
 typedef int
 (*virDomainNetBandwidthUpdateImpl)(virDomainNetDefPtr iface,
                                    virNetDevBandwidthPtr newBandwidth);
@@ -3597,7 +3593,6 @@ void
 virDomainNetSetDeviceImpl(virDomainNetAllocateActualDeviceImpl allocate,
                           virDomainNetNotifyActualDeviceImpl notify,
                           virDomainNetReleaseActualDeviceImpl release,
-                          virDomainNetBandwidthChangeAllowedImpl bandwidthChangeAllowed,
                           virDomainNetBandwidthUpdateImpl bandwidthUpdate);
 
 int
@@ -3618,11 +3613,6 @@ virDomainNetReleaseActualDevice(virConnectPtr conn,
                                 virDomainNetDefPtr iface)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
-bool
-virDomainNetBandwidthChangeAllowed(virDomainNetDefPtr iface,
-                              virNetDevBandwidthPtr newBandwidth)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
-
 int
 virDomainNetBandwidthUpdate(virDomainNetDefPtr iface,
                             virNetDevBandwidthPtr newBandwidth)

src/libvirt_private.syms

@@ -456,7 +456,6 @@ virDomainMemorySourceTypeFromString;
 virDomainMemorySourceTypeToString;
 virDomainNetAllocateActualDevice;
 virDomainNetAppendIPAddress;
-virDomainNetBandwidthChangeAllowed;
 virDomainNetBandwidthUpdate;
 virDomainNetDefActualFromNetworkPort;
 virDomainNetDefActualToNetworkPort;

src/network/bridge_driver.c

@@ -5349,64 +5349,6 @@ networkNetworkObjTaint(virNetworkObjPtr obj,
 }
 
 
-static bool
-networkBandwidthGenericChecks(virDomainNetDefPtr iface,
-                              virNetDevBandwidthPtr newBandwidth)
-{
-    virNetDevBandwidthPtr ifaceBand;
-    unsigned long long old_floor, new_floor;
-
-    if (virDomainNetGetActualType(iface) != VIR_DOMAIN_NET_TYPE_NETWORK &&
-        (virDomainNetGetActualType(iface) != VIR_DOMAIN_NET_TYPE_BRIDGE ||
-         iface->data.network.actual->data.bridge.brname == NULL)) {
-        /* This is not an interface that's plugged into a network.
-         * We don't care. Thus from our POV bandwidth change is allowed. */
-        return false;
-    }
-
-    ifaceBand = virDomainNetGetActualBandwidth(iface);
-    old_floor = new_floor = 0;
-
-    if (ifaceBand && ifaceBand->in)
-        old_floor = ifaceBand->in->floor;
-    if (newBandwidth && newBandwidth->in)
-        new_floor = newBandwidth->in->floor;
-
-    return new_floor != old_floor;
-}
-
-
-static bool
-networkBandwidthChangeAllowed(virDomainNetDefPtr iface,
-                              virNetDevBandwidthPtr newBandwidth)
-{
-    virNetworkDriverStatePtr driver = networkGetDriver();
-    virNetworkObjPtr obj = NULL;
-    virNetDevBandwidthPtr ifaceBand = virDomainNetGetActualBandwidth(iface);
-    bool ret = false;
-
-    if (!networkBandwidthGenericChecks(iface, newBandwidth))
-        return true;
-
-    obj = virNetworkObjFindByName(driver->networks, iface->data.network.name);
-    if (!obj) {
-        virReportError(VIR_ERR_NO_NETWORK,
-                       _("no network with matching name '%s'"),
-                       iface->data.network.name);
-        return false;
-    }
-
-    if (networkCheckBandwidth(obj, newBandwidth, ifaceBand, &iface->mac, NULL) < 0)
-        goto cleanup;
-
-    ret = true;
-
- cleanup:
-    virNetworkObjEndAPI(&obj);
-    return ret;
-}
-
-
 static int
 networkBandwidthUpdate(virDomainNetDefPtr iface,
                        virNetDevBandwidthPtr newBandwidth)
@@ -5417,6 +5359,7 @@ networkBandwidthUpdate(virDomainNetDefPtr iface,
     unsigned long long tmp_floor_sum;
     virNetDevBandwidthPtr ifaceBand = virDomainNetGetActualBandwidth(iface);
     unsigned long long new_rate = 0;
+    unsigned long long old_floor, new_floor;
     int plug_ret;
     int ret = -1;
 
@@ -5426,7 +5369,22 @@ networkBandwidthUpdate(virDomainNetDefPtr iface,
         return -1;
     }
 
-    if (!networkBandwidthGenericChecks(iface, newBandwidth))
+    if (virDomainNetGetActualType(iface) != VIR_DOMAIN_NET_TYPE_NETWORK &&
+        (virDomainNetGetActualType(iface) != VIR_DOMAIN_NET_TYPE_BRIDGE ||
+         iface->data.network.actual->data.bridge.brname != NULL)) {
+        /* This is not an interface that's plugged into a bridge.
+         * We don't care. Thus from our POV bandwidth change is allowed. */
+        return 0;
+    }
+
+    old_floor = new_floor = 0;
+
+    if (ifaceBand && ifaceBand->in)
+        old_floor = ifaceBand->in->floor;
+    if (newBandwidth && newBandwidth->in)
+        new_floor = newBandwidth->in->floor;
+
+    if (new_floor == old_floor)
         return 0;
 
     obj = virNetworkObjFindByName(driver->networks, iface->data.network.name);
@@ -5572,7 +5530,6 @@ networkRegister(void)
         networkAllocateActualDevice,
         networkNotifyActualDevice,
         networkReleaseActualDevice,
-        networkBandwidthChangeAllowed,
         networkBandwidthUpdate);
 
     return 0;

src/qemu/qemu_driver.c

@@ -11625,17 +11625,17 @@ qemuDomainSetInterfaceParameters(virDomainPtr dom,
         }
 
         if (net->type == VIR_DOMAIN_NET_TYPE_NETWORK &&
-            !virDomainNetBandwidthChangeAllowed(net, newBandwidth))
+            virDomainNetBandwidthUpdate(net, newBandwidth) < 0)
             goto endjob;
 
         if (virNetDevBandwidthSet(net->ifname, newBandwidth, false,
-                                  !virDomainNetTypeSharesHostView(net)) < 0 ||
-            (net->type == VIR_DOMAIN_NET_TYPE_NETWORK &&
-             virDomainNetBandwidthUpdate(net, newBandwidth) < 0)) {
+                                  !virDomainNetTypeSharesHostView(net)) < 0) {
             ignore_value(virNetDevBandwidthSet(net->ifname,
                                                net->bandwidth,
                                                false,
                                                !virDomainNetTypeSharesHostView(net)));
+            ignore_value(virDomainNetBandwidthUpdate(net,
+                                                     net->bandwidth));
             goto endjob;
         }