core: vnic hot un\plug - avoid race

Lack of a lock in ActivateDeactivateVmNicCommand allows several
instances of hot plug and unplug requests to run in parallel causing
inconsistency in vNIC status as well as libvirt failing the requests due
to non-unique aliases. This patch adds a lock to the command so that
each instance of the command has to finish before the next one starts.

Bug-Url: https://bugzilla.redhat.com/2084530
Change-Id: I93ac9f1f12f34526ad10b9a49790c3a2689e8c4d
Signed-off-by: Eitan Raviv <eraviv@redhat.com>

backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/network/vm/ActivateDeactivateVmNicCommand.java

@@ -5,6 +5,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 import javax.inject.Inject;
 
@@ -54,6 +56,7 @@
 import org.ovirt.engine.core.dao.provider.ProviderDao;
 import org.ovirt.engine.core.utils.ReplacementUtils;
 import org.ovirt.engine.core.utils.StringMapUtils;
+import org.ovirt.engine.core.vdsbroker.ResourceManager;
 import org.ovirt.engine.core.vdsbroker.monitoring.VmDevicesMonitoring;
 import org.ovirt.engine.core.vdsbroker.vdsbroker.VdsProperties;
 import org.ovirt.engine.core.vdsbroker.vdsbroker.VmInfoReturn;
@@ -118,6 +121,9 @@ public class ActivateDeactivateVmNicCommand<T extends ActivateDeactivateVmNicPar
     @Inject
     private NetworkDao networkDao;
 
+    @Inject
+    private ResourceManager resourceManager;
+
     public ActivateDeactivateVmNicCommand(T parameters, CommandContext commandContext) {
         super(parameters, commandContext);
         setVmId(parameters.getVmId());
@@ -248,21 +254,43 @@ public String getInterfaceType() {
 
     @Override
     protected void executeVmCommand() {
-        switch (getParameters().getAction()) {
-        case PLUG:
-            plugNic();
-            break;
-        case UNPLUG:
-            unplugNic();
-            break;
-        default:
-            throw new RuntimeException("Coding error: unknown enum value");
+        boolean hotPlug = getVm().getStatus().isUpOrPaused();
+        Lock vmDevicesLock = getVmDevicesLock(hotPlug);
+        vmDevicesLock.lock();
+        try {
+            switch (getParameters().getAction()) {
+            case PLUG:
+                plugNic();
+                break;
+            case UNPLUG:
+                unplugNic();
+                break;
+            default:
+                throw new RuntimeException("Coding error: unknown enum value");
+            }
+
+            var success = handleFailoverIfNeeded();
+            // In any case, the device is updated
+            updateDevice();
+            setSucceeded(success);
+        } finally {
+            vmDevicesLock.unlock();
         }
+    }
 
-        var success = handleFailoverIfNeeded();
-        // In any case, the device is updated
-        updateDevice();
-        setSucceeded(success);
+    protected Lock getVmDevicesLock(boolean runningVmChanges) {
+        if (!runningVmChanges) {
+            // dummy lock
+            return new ReentrantLock() {
+                @Override
+                public void lock() {
+                }
+                @Override
+                public void unlock() {
+                }
+            };
+        }
+        return resourceManager.getVmManager(getVmId()).getVmDevicesLock();
     }
 
     private void plugNic() {