From 3188a720b9f7d9335af7718862ca96f1cae6d4b1 Mon Sep 17 00:00:00 2001
Message-Id: <3188a720b9f7d9335af7718862ca96f1cae6d4b1@dist-git>
From: Pavel Hrdina <phrdina@redhat.com>
Date: Thu, 13 Nov 2014 11:19:10 +0100
Subject: [PATCH] nwfilter: fix deadlock caused updating network device and
 nwfilter

Commit 6e5c79a1 tried to fix deadlock between nwfilter{Define,Undefine}
and starting of guest, but this same deadlock exists for
updating/attaching network device to domain.

The deadlock was introduced by removing global QEMU driver lock because
nwfilter was counting on this lock and ensure that all driver locks are
locked inside of nwfilter{Define,Undefine}.

This patch extends usage of virNWFilterReadLockFilterUpdates to prevent
the deadlock for all possible paths in QEMU driver. LXC and UML drivers
still have global lock.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1143780

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
(cherry picked from commit 41127244fb90f08cf5032a5d7553f5f0390d925e)
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_driver.c    | 12 ++++++++++++
 src/qemu/qemu_migration.c |  4 ++++
 src/qemu/qemu_process.c   |  5 +++++
 3 files changed, 21 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index d419689..6ed830c 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5902,6 +5902,8 @@ qemuDomainRestoreFlags(virConnectPtr conn,
                   VIR_DOMAIN_SAVE_PAUSED, -1);
 
 
+    virNWFilterReadLockFilterUpdates();
+
     fd = qemuDomainSaveImageOpen(driver, path, &def, &header, &xml,
                                  (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
                                  &wrapperFd, false, false);
@@ -5979,6 +5981,7 @@ qemuDomainRestoreFlags(virConnectPtr conn,
     virFileWrapperFdFree(wrapperFd);
     if (vm)
         virObjectUnlock(vm);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -7412,6 +7415,8 @@ static int qemuDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
     virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
                   VIR_DOMAIN_AFFECT_CONFIG, -1);
 
+    virNWFilterReadLockFilterUpdates();
+
     cfg = virQEMUDriverGetConfig(driver);
 
     affect = flags & (VIR_DOMAIN_AFFECT_LIVE | VIR_DOMAIN_AFFECT_CONFIG);
@@ -7528,6 +7533,7 @@ static int qemuDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -7558,6 +7564,8 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
                   VIR_DOMAIN_AFFECT_CONFIG |
                   VIR_DOMAIN_DEVICE_MODIFY_FORCE, -1);
 
+    virNWFilterReadLockFilterUpdates();
+
     cfg = virQEMUDriverGetConfig(driver);
 
     affect = flags & (VIR_DOMAIN_AFFECT_LIVE | VIR_DOMAIN_AFFECT_CONFIG);
@@ -7674,6 +7682,7 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -14415,6 +14424,8 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
      * and use of FORCE can cause multiple transitions.
      */
 
+    virNWFilterReadLockFilterUpdates();
+
     if (!(vm = qemuDomObjFromSnapshot(snapshot)))
         return -1;
 
@@ -14736,6 +14747,7 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
 
     return ret;
 }
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 98fd376..d6c8553 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -57,6 +57,7 @@
 #include "virstring.h"
 #include "virtypedparam.h"
 #include "virprocess.h"
+#include "nwfilter_conf.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
@@ -2525,6 +2526,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
     if (virTimeMillisNow(&now) < 0)
         return -1;
 
+    virNWFilterReadLockFilterUpdates();
+
     if (flags & VIR_MIGRATE_OFFLINE) {
         if (flags & (VIR_MIGRATE_NON_SHARED_DISK |
                      VIR_MIGRATE_NON_SHARED_INC)) {
@@ -2834,6 +2837,7 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
         qemuDomainEventQueue(driver, event);
     qemuMigrationCookieFree(mig);
     virObjectUnref(caps);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 
  stop:
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index ed095a2..9c640f0 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -68,6 +68,7 @@
 #include "virhostdev.h"
 #include "storage/storage_driver.h"
 #include "configmake.h"
+#include "nwfilter_conf.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
 
@@ -3420,6 +3421,8 @@ qemuProcessReconnect(void *opaque)
 
     VIR_FREE(data);
 
+    virNWFilterReadLockFilterUpdates();
+
     virObjectLock(obj);
 
     cfg = virQEMUDriverGetConfig(driver);
@@ -3571,6 +3574,7 @@ qemuProcessReconnect(void *opaque)
 
     virObjectUnref(conn);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
 
     return;
 
@@ -3606,6 +3610,7 @@ qemuProcessReconnect(void *opaque)
     }
     virObjectUnref(conn);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
 }
 
 static int
-- 
2.1.3