From 2331e5c8d13ea2352a20c93166a9287e25196353 Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Wed, 22 Jan 2014 17:28:29 +0000 Subject: [PATCH] Push nwfilter update locking up to top level The NWFilter code has as a deadlock race condition between the virNWFilter{Define,Undefine} APIs and starting of guest VMs due to mis-matched lock ordering. In the virNWFilter{Define,Undefine} codepaths the lock ordering is 1. nwfilter driver lock 2. virt driver lock 3. nwfilter update lock 4. domain object lock In the VM guest startup paths the lock ordering is 1. virt driver lock 2. domain object lock 3. nwfilter update lock As can be seen the domain object and nwfilter update locks are not acquired in a consistent order. The fix used is to push the nwfilter update lock upto the top level resulting in a lock ordering for virNWFilter{Define,Undefine} of 1. nwfilter driver lock 2. nwfilter update lock 3. virt driver lock 4. domain object lock and VM start using 1. nwfilter update lock 2. virt driver lock 3. domain object lock This has the effect of serializing VM startup once again, even if no nwfilters are applied to the guest. There is also the possibility of deadlock due to a call graph loop via virNWFilterInstantiate and virNWFilterInstantiateFilterLate. These two problems mean the lock must be turned into a read/write lock instead of a plain mutex at the same time. The lock is used to serialize changes to the "driver->nwfilters" hash, so the write lock only needs to be held by the define/undefine methods. All other methods can rely on a read lock which allows good concurrency. Signed-off-by: Daniel P. Berrange (cherry picked from commit 6e5c79a1b5a8b3a23e7df7ffe58fb272aa17fbfb) Conflicts: src/conf/nwfilter_conf.c - virReportOOMError() in context of one hunk. src/lxc/lxc_driver.c - functions renamed, and lxc object locking changed, creating a conflict in the context. --- src/conf/nwfilter_conf.c | 25 ++++++++++++------------- src/conf/nwfilter_conf.h | 3 ++- src/libvirt_private.syms | 3 ++- src/lxc/lxc_driver.c | 8 +++++++- src/nwfilter/nwfilter_driver.c | 10 ++++++---- src/nwfilter/nwfilter_gentech_driver.c | 6 +----- src/qemu/qemu_driver.c | 6 ++++++ src/uml/uml_driver.c | 4 ++++ 8 files changed, 40 insertions(+), 25 deletions(-) diff --git a/src/conf/nwfilter_conf.c b/src/conf/nwfilter_conf.c index 94b4fe99da..e943babe43 100644 --- a/src/conf/nwfilter_conf.c +++ b/src/conf/nwfilter_conf.c @@ -2,7 +2,7 @@ * nwfilter_conf.c: network filter XML processing * (derived from storage_conf.c) * - * Copyright (C) 2006-2012 Red Hat, Inc. + * Copyright (C) 2006-2012, 2014 Red Hat, Inc. * Copyright (C) 2006-2008 Daniel P. Berrange * * Copyright (C) 2010-2011 IBM Corporation @@ -143,17 +143,22 @@ static const struct int_map chain_priorities[] = { /* * only one filter update allowed */ -static virMutex updateMutex; +static virRWLock updateLock; static bool initialized = false; void -virNWFilterLockFilterUpdates(void) { - virMutexLock(&updateMutex); +virNWFilterReadLockFilterUpdates(void) { + virRWLockRead(&updateLock); +} + +void +virNWFilterWriteLockFilterUpdates(void) { + virRWLockWrite(&updateLock); } void virNWFilterUnlockFilterUpdates(void) { - virMutexUnlock(&updateMutex); + virRWLockUnlock(&updateLock); } @@ -2992,14 +2997,12 @@ virNWFilterObjAssignDef(virNWFilterObjListPtr nwfilters, return NULL; } - virNWFilterLockFilterUpdates(); if ((nwfilter = virNWFilterObjFindByName(nwfilters, def->name))) { if (virNWFilterDefEqual(def, nwfilter->def, false)) { virNWFilterDefFree(nwfilter->def); nwfilter->def = def; - virNWFilterUnlockFilterUpdates(); return nwfilter; } @@ -3007,7 +3010,6 @@ virNWFilterObjAssignDef(virNWFilterObjListPtr nwfilters, /* trigger the update on VMs referencing the filter */ if (virNWFilterTriggerVMFilterRebuild()) { nwfilter->newDef = NULL; - virNWFilterUnlockFilterUpdates(); virNWFilterObjUnlock(nwfilter); return NULL; } @@ -3015,12 +3017,9 @@ virNWFilterObjAssignDef(virNWFilterObjListPtr nwfilters, virNWFilterDefFree(nwfilter->def); nwfilter->def = def; nwfilter->newDef = NULL; - virNWFilterUnlockFilterUpdates(); return nwfilter; } - virNWFilterUnlockFilterUpdates(); - if (VIR_ALLOC(nwfilter) < 0) { virReportOOMError(); return NULL; @@ -3492,7 +3491,7 @@ int virNWFilterConfLayerInit(virDomainObjListIterator domUpdateCB, initialized = true; - if (virMutexInitRecursive(&updateMutex) < 0) + if (virRWLockInit(&updateLock) < 0) return -1; return 0; @@ -3504,7 +3503,7 @@ void virNWFilterConfLayerShutdown(void) if (!initialized) return; - virMutexDestroy(&updateMutex); + virRWLockDestroy(&updateLock); initialized = false; virNWFilterDomainFWUpdateOpaque = NULL; diff --git a/src/conf/nwfilter_conf.h b/src/conf/nwfilter_conf.h index 29906f1389..d460a08565 100644 --- a/src/conf/nwfilter_conf.h +++ b/src/conf/nwfilter_conf.h @@ -716,7 +716,8 @@ virNWFilterDefPtr virNWFilterDefParseFile(const char *filename); void virNWFilterObjLock(virNWFilterObjPtr obj); void virNWFilterObjUnlock(virNWFilterObjPtr obj); -void virNWFilterLockFilterUpdates(void); +void virNWFilterWriteLockFilterUpdates(void); +void virNWFilterReadLockFilterUpdates(void); void virNWFilterUnlockFilterUpdates(void); int virNWFilterConfLayerInit(virDomainObjListIterator domUpdateCB, void *opaque); diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index a6348bcfeb..753c698d4b 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -551,7 +551,6 @@ virNWFilterDefParseString; virNWFilterInstFiltersOnAllVMs; virNWFilterJumpTargetTypeToString; virNWFilterLoadAllConfigs; -virNWFilterLockFilterUpdates; virNWFilterObjAssignDef; virNWFilterObjDeleteDef; virNWFilterObjFindByName; @@ -563,6 +562,7 @@ virNWFilterObjSaveDef; virNWFilterObjUnlock; virNWFilterPrintStateMatchFlags; virNWFilterPrintTCPFlags; +virNWFilterReadLockFilterUpdates; virNWFilterRegisterCallbackDriver; virNWFilterRuleActionTypeToString; virNWFilterRuleDirectionTypeToString; @@ -570,6 +570,7 @@ virNWFilterRuleProtocolTypeToString; virNWFilterTestUnassignDef; virNWFilterUnlockFilterUpdates; virNWFilterUnRegisterCallbackDriver; +virNWFilterWriteLockFilterUpdates; # conf/nwfilter_ipaddrmap.h diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c index fed3775a23..d59f0f6a9e 100644 --- a/src/lxc/lxc_driver.c +++ b/src/lxc/lxc_driver.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2010-2013 Red Hat, Inc. + * Copyright (C) 2010-2014 Red Hat, Inc. * Copyright IBM Corp. 2008 * * lxc_driver.c: linux container driver functions @@ -1102,6 +1102,8 @@ static int lxcDomainCreateWithFlags(virDomainPtr dom, unsigned int flags) virCheckFlags(VIR_DOMAIN_START_AUTODESTROY, -1); + virNWFilterReadLockFilterUpdates(); + lxcDriverLock(driver); vm = virDomainObjListFindByUUID(driver->domains, dom->uuid); if (!vm) { @@ -1146,6 +1148,7 @@ cleanup: if (event) virDomainEventStateQueue(driver->domainEventState, event); lxcDriverUnlock(driver); + virNWFilterUnlockFilterUpdates(); return ret; } @@ -1184,6 +1187,8 @@ lxcDomainCreateXML(virConnectPtr conn, virCheckFlags(VIR_DOMAIN_START_AUTODESTROY, NULL); + virNWFilterReadLockFilterUpdates(); + lxcDriverLock(driver); if (!(def = virDomainDefParseString(xml, driver->caps, driver->xmlopt, 1 << VIR_DOMAIN_VIRT_LXC, @@ -1235,6 +1240,7 @@ cleanup: if (event) virDomainEventStateQueue(driver->domainEventState, event); lxcDriverUnlock(driver); + virNWFilterUnlockFilterUpdates(); return dom; } diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c index 630f622725..2d5dcaf831 100644 --- a/src/nwfilter/nwfilter_driver.c +++ b/src/nwfilter/nwfilter_driver.c @@ -284,12 +284,14 @@ nwfilterStateReload(void) virNWFilterLearnThreadsTerminate(true); nwfilterDriverLock(driverState); + virNWFilterWriteLockFilterUpdates(); virNWFilterCallbackDriversLock(); virNWFilterLoadAllConfigs(&driverState->nwfilters, driverState->configDir); virNWFilterCallbackDriversUnlock(); + virNWFilterUnlockFilterUpdates(); nwfilterDriverUnlock(driverState); virNWFilterInstFiltersOnAllVMs(); @@ -540,6 +542,7 @@ nwfilterDefineXML(virConnectPtr conn, virNWFilterPtr ret = NULL; nwfilterDriverLock(driver); + virNWFilterWriteLockFilterUpdates(); virNWFilterCallbackDriversLock(); if (!(def = virNWFilterDefParseString(xml))) @@ -566,6 +569,7 @@ cleanup: virNWFilterObjUnlock(nwfilter); virNWFilterCallbackDriversUnlock(); + virNWFilterUnlockFilterUpdates(); nwfilterDriverUnlock(driver); return ret; } @@ -578,10 +582,9 @@ nwfilterUndefine(virNWFilterPtr obj) { int ret = -1; nwfilterDriverLock(driver); + virNWFilterWriteLockFilterUpdates(); virNWFilterCallbackDriversLock(); - virNWFilterLockFilterUpdates(); - nwfilter = virNWFilterObjFindByUUID(&driver->nwfilters, obj->uuid); if (!nwfilter) { virReportError(VIR_ERR_NO_NWFILTER, @@ -612,9 +615,8 @@ cleanup: if (nwfilter) virNWFilterObjUnlock(nwfilter); - virNWFilterUnlockFilterUpdates(); - virNWFilterCallbackDriversUnlock(); + virNWFilterUnlockFilterUpdates(); nwfilterDriverUnlock(driver); return ret; } diff --git a/src/nwfilter/nwfilter_gentech_driver.c b/src/nwfilter/nwfilter_gentech_driver.c index 637e647fbb..c9ce5142d3 100644 --- a/src/nwfilter/nwfilter_gentech_driver.c +++ b/src/nwfilter/nwfilter_gentech_driver.c @@ -947,8 +947,6 @@ _virNWFilterInstantiateFilter(virNWFilterDriverStatePtr driver, int ifindex; int rc; - virNWFilterLockFilterUpdates(); - /* after grabbing the filter update lock check for the interface; if it's not there anymore its filters will be or are being removed (while holding the lock) and we don't want to build new ones */ @@ -976,8 +974,6 @@ _virNWFilterInstantiateFilter(virNWFilterDriverStatePtr driver, foundNewFilter); cleanup: - virNWFilterUnlockFilterUpdates(); - return rc; } @@ -996,7 +992,7 @@ virNWFilterInstantiateFilterLate(virNWFilterDriverStatePtr driver, int rc; bool foundNewFilter = false; - virNWFilterLockFilterUpdates(); + virNWFilterReadLockFilterUpdates(); rc = __virNWFilterInstantiateFilter(driver, vmuuid, diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 8ebfadd681..b209614c06 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -1542,6 +1542,8 @@ static virDomainPtr qemuDomainCreateXML(virConnectPtr conn, if (flags & VIR_DOMAIN_START_AUTODESTROY) start_flags |= VIR_QEMU_PROCESS_START_AUTODESTROY; + virNWFilterReadLockFilterUpdates(); + if (!(caps = virQEMUDriverGetCapabilities(driver, false))) goto cleanup; @@ -1619,6 +1621,7 @@ cleanup: } virObjectUnref(caps); virObjectUnref(qemuCaps); + virNWFilterUnlockFilterUpdates(); return dom; } @@ -5846,6 +5849,8 @@ qemuDomainCreateWithFlags(virDomainPtr dom, unsigned int flags) VIR_DOMAIN_START_BYPASS_CACHE | VIR_DOMAIN_START_FORCE_BOOT, -1); + virNWFilterReadLockFilterUpdates(); + if (!(vm = qemuDomObjFromDomain(dom))) return -1; @@ -5873,6 +5878,7 @@ endjob: cleanup: if (vm) virObjectUnlock(vm); + virNWFilterUnlockFilterUpdates(); return ret; } diff --git a/src/uml/uml_driver.c b/src/uml/uml_driver.c index 74aa94a69e..5947082d0c 100644 --- a/src/uml/uml_driver.c +++ b/src/uml/uml_driver.c @@ -1572,6 +1572,7 @@ static virDomainPtr umlDomainCreateXML(virConnectPtr conn, const char *xml, virCheckFlags(VIR_DOMAIN_START_AUTODESTROY, NULL); + virNWFilterReadLockFilterUpdates(); umlDriverLock(driver); if (!(def = virDomainDefParseString(xml, driver->caps, driver->xmlopt, 1 << VIR_DOMAIN_VIRT_UML, @@ -1611,6 +1612,7 @@ cleanup: if (event) umlDomainEventQueue(driver, event); umlDriverUnlock(driver); + virNWFilterUnlockFilterUpdates(); return dom; } @@ -1993,6 +1995,7 @@ static int umlDomainCreateWithFlags(virDomainPtr dom, unsigned int flags) { virCheckFlags(VIR_DOMAIN_START_AUTODESTROY, -1); + virNWFilterReadLockFilterUpdates(); umlDriverLock(driver); vm = virDomainObjListFindByUUID(driver->domains, dom->uuid); @@ -2019,6 +2022,7 @@ cleanup: if (event) umlDomainEventQueue(driver, event); umlDriverUnlock(driver); + virNWFilterUnlockFilterUpdates(); return ret; } -- GitLab