From 26a87687c72733593305a6bb60d5bf02a12efc15 Mon Sep 17 00:00:00 2001
From: Pavel Hrdina <phrdina@redhat.com>
Date: Wed, 5 Nov 2014 14:28:57 +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)
---
 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 bb445fe70d..b789189e62 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -5700,6 +5700,8 @@ 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);
@@ -5777,6 +5779,7 @@ qemuDomainRestoreFlags(virConnectPtr conn,
     virFileWrapperFdFree(wrapperFd);
     if (vm)
         virObjectUnlock(vm);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -7210,6 +7213,8 @@ 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);
@@ -7326,6 +7331,7 @@ static int qemuDomainAttachDeviceFlags(virDomainPtr dom, const char *xml,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -7356,6 +7362,8 @@ 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);
@@ -7472,6 +7480,7 @@ static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
         virObjectUnlock(vm);
     virObjectUnref(caps);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
     return ret;
 }
 
@@ -14159,6 +14168,8 @@ qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
      * and use of FORCE can cause multiple transitions.
      */
 
+    virNWFilterReadLockFilterUpdates();
+
     if (!(vm = qemuDomObjFromSnapshot(snapshot)))
         return -1;
 
@@ -14480,6 +14491,7 @@ 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 9dac1e021e..b3c911ee30 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
 
@@ -2524,6 +2525,8 @@ 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)) {
@@ -2833,6 +2836,7 @@ 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 d254767beb..a1f9c53b1a 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
 
@@ -3389,6 +3390,8 @@ qemuProcessReconnect(void *opaque)
 
     VIR_FREE(data);
 
+    virNWFilterReadLockFilterUpdates();
+
     virObjectLock(obj);
 
     cfg = virQEMUDriverGetConfig(driver);
@@ -3540,6 +3543,7 @@ qemuProcessReconnect(void *opaque)
 
     virObjectUnref(conn);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
 
     return;
 
@@ -3575,6 +3579,7 @@ qemuProcessReconnect(void *opaque)
     }
     virObjectUnref(conn);
     virObjectUnref(cfg);
+    virNWFilterUnlockFilterUpdates();
 }
 
 static int
-- 
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