The meat of this patch is just moving the calls to virNWFilterRegisterCallbackDriver from each hypervisor's "register" function into its "initialize" function. The rest is just code movement to allow that, and a new virNWFilterUnRegisterCallbackDriver function to undo what the register function does. The long explanation: There is an array in nwfilter called callbackDrvArray that has pointers to a table of functions for each hypervisor driver that are called by nwfilter. One of those function pointers is to a function that will lock the hypervisor driver. Entries are added to the table by calling each driver's "register" function, which happens quite early in libvirtd's startup. Sometime later, each driver's "initialize" function is called. This function allocates a driver object and stores a pointer to it in a static variable that was previously initialized to NULL. (and here's the important part...) If the "initialize" function fails, the driver object is freed, and that pointer set back to NULL (but the entry in nwfilter's callbackDrvArray is still there). When the "lock the driver" function mentioned above is called, it assumes that the driver was successfully loaded, so it blindly tries to call virMutexLock on "driver->lock". BUT, if the initialize never happened, or if it failed, "driver" is NULL. And it just happens that "lock" is always the first field in driver so it is also NULL. Boom. To fix this, the call to virNWFilterRegisterCallbackDriver for each driver shouldn't be called until the end of its (*already guaranteed successful*) "initialize" function, not during its "register" function (which is currently the case). This implies that there should also be a virNWFilterUnregisterCallbackDriver() function that is called in a driver's "shutdown" function (although in practice, that function is currently never called). --- src/conf/nwfilter_conf.c | 18 +++++++++++++++ src/conf/nwfilter_conf.h | 3 ++- src/libvirt_private.syms | 1 + src/lxc/lxc_driver.c | 60 +++++++++++++++++++++++++----------------------- src/qemu/qemu_driver.c | 60 +++++++++++++++++++++++++----------------------- src/uml/uml_driver.c | 59 ++++++++++++++++++++++++----------------------- 6 files changed, 113 insertions(+), 88 deletions(-) diff --git a/src/conf/nwfilter_conf.c b/src/conf/nwfilter_conf.c index 665ea0c..4fbbc78 100644 --- a/src/conf/nwfilter_conf.c +++ b/src/conf/nwfilter_conf.c @@ -2829,6 +2829,24 @@ virNWFilterRegisterCallbackDriver(virNWFilterCallbackDriverPtr cbd) } void +virNWFilterUnRegisterCallbackDriver(virNWFilterCallbackDriverPtr cbd) +{ + int i = 0; + + while (i < nCallbackDriver && callbackDrvArray[i] != cbd) + i++; + + if (i < nCallbackDriver) { + while (i < nCallbackDriver - 1) { + callbackDrvArray[i] = callbackDrvArray[i+1]; + i++; + } + callbackDrvArray[i] = 0; + nCallbackDriver--; + } +} + +void virNWFilterCallbackDriversLock(void) { int i; diff --git a/src/conf/nwfilter_conf.h b/src/conf/nwfilter_conf.h index 8b05d04..4b58581 100644 --- a/src/conf/nwfilter_conf.h +++ b/src/conf/nwfilter_conf.h @@ -2,7 +2,7 @@ * nwfilter_conf.h: network filter XML processing * (derived from storage_conf.h) * - * Copyright (C) 2006-2010 Red Hat, Inc. + * Copyright (C) 2006-2010, 2012 Red Hat, Inc. * Copyright (C) 2006-2008 Daniel P. Berrange * * Copyright (C) 2010 IBM Corporation @@ -748,6 +748,7 @@ struct _virNWFilterCallbackDriver { }; void virNWFilterRegisterCallbackDriver(virNWFilterCallbackDriverPtr); +void virNWFilterUnRegisterCallbackDriver(virNWFilterCallbackDriverPtr); void virNWFilterCallbackDriversLock(void); void virNWFilterCallbackDriversUnlock(void); diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 79b4a18..c023dbf 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -880,6 +880,7 @@ virNWFilterRuleActionTypeToString; virNWFilterRuleDirectionTypeToString; virNWFilterRuleProtocolTypeToString; virNWFilterTestUnassignDef; +virNWFilterUnRegisterCallbackDriver; virNWFilterUnlockFilterUpdates; diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c index d118dd2..b7b119c 100644 --- a/src/lxc/lxc_driver.c +++ b/src/lxc/lxc_driver.c @@ -74,6 +74,35 @@ static int lxcStartup(int privileged); static int lxcShutdown(void); virLXCDriverPtr lxc_driver = NULL; +/* callbacks for nwfilter */ +static int +lxcVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, + virHashIterator iter, void *data) +{ + virHashForEach(lxc_driver->domains.objs, iter, data); + + return 0; +} + +static void +lxcVMDriverLock(void) +{ + lxcDriverLock(lxc_driver); +} + +static void +lxcVMDriverUnlock(void) +{ + lxcDriverUnlock(lxc_driver); +} + +static virNWFilterCallbackDriver lxcCallbackDriver = { + .name = "LXC", + .vmFilterRebuild = lxcVMFilterRebuild, + .vmDriverLock = lxcVMDriverLock, + .vmDriverUnlock = lxcVMDriverUnlock, +}; + /* Functions */ static virDrvOpenStatus lxcOpen(virConnectPtr conn, @@ -1465,6 +1494,7 @@ static int lxcStartup(int privileged) virLXCProcessAutostartAll(lxc_driver); + virNWFilterRegisterCallbackDriver(&lxcCallbackDriver); return 0; cleanup: @@ -1516,6 +1546,7 @@ static int lxcShutdown(void) return -1; lxcDriverLock(lxc_driver); + virNWFilterUnRegisterCallbackDriver(&lxcCallbackDriver); virDomainObjListDeinit(&lxc_driver->domains); virDomainEventStateFree(lxc_driver->domainEventState); @@ -2654,34 +2685,6 @@ lxcListAllDomains(virConnectPtr conn, return ret; } -static int -lxcVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, - virHashIterator iter, void *data) -{ - virHashForEach(lxc_driver->domains.objs, iter, data); - - return 0; -} - -static void -lxcVMDriverLock(void) -{ - lxcDriverLock(lxc_driver); -} - -static void -lxcVMDriverUnlock(void) -{ - lxcDriverUnlock(lxc_driver); -} - -static virNWFilterCallbackDriver lxcCallbackDriver = { - .name = "LXC", - .vmFilterRebuild = lxcVMFilterRebuild, - .vmDriverLock = lxcVMDriverLock, - .vmDriverUnlock = lxcVMDriverUnlock, -}; - /* Function Tables */ static virDriver lxcDriver = { .no = VIR_DRV_LXC, @@ -2761,6 +2764,5 @@ int lxcRegister(void) { virRegisterDriver(&lxcDriver); virRegisterStateDriver(&lxcStateDriver); - virNWFilterRegisterCallbackDriver(&lxcCallbackDriver); return 0; } diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index dee1268..9bf89bb 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -148,6 +148,35 @@ static void qemuDomainManagedSaveLoad(void *payload, struct qemud_driver *qemu_driver = NULL; +static void +qemuVMDriverLock(void) { + qemuDriverLock(qemu_driver); +}; + + +static void +qemuVMDriverUnlock(void) { + qemuDriverUnlock(qemu_driver); +}; + + +static int +qemuVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, + virHashIterator iter, void *data) +{ + virHashForEach(qemu_driver->domains.objs, iter, data); + + return 0; +} + +static virNWFilterCallbackDriver qemuCallbackDriver = { + .name = QEMU_DRIVER_NAME, + .vmFilterRebuild = qemuVMFilterRebuild, + .vmDriverLock = qemuVMDriverLock, + .vmDriverUnlock = qemuVMDriverUnlock, +}; + + struct qemuAutostartData { struct qemud_driver *driver; virConnectPtr conn; @@ -754,6 +783,7 @@ qemudStartup(int privileged) { if (conn) virConnectClose(conn); + virNWFilterRegisterCallbackDriver(&qemuCallbackDriver); return 0; out_of_memory: @@ -843,6 +873,7 @@ qemudShutdown(void) { return -1; qemuDriverLock(qemu_driver); + virNWFilterUnRegisterCallbackDriver(&qemuCallbackDriver); pciDeviceListFree(qemu_driver->activePciHostdevs); pciDeviceListFree(qemu_driver->inactivePciHostdevs); usbDeviceListFree(qemu_driver->activeUsbHostdevs); @@ -13380,37 +13411,8 @@ static virStateDriver qemuStateDriver = { .active = qemudActive, }; -static void -qemuVMDriverLock(void) { - qemuDriverLock(qemu_driver); -}; - - -static void -qemuVMDriverUnlock(void) { - qemuDriverUnlock(qemu_driver); -}; - - -static int -qemuVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, - virHashIterator iter, void *data) -{ - virHashForEach(qemu_driver->domains.objs, iter, data); - - return 0; -} - -static virNWFilterCallbackDriver qemuCallbackDriver = { - .name = QEMU_DRIVER_NAME, - .vmFilterRebuild = qemuVMFilterRebuild, - .vmDriverLock = qemuVMDriverLock, - .vmDriverUnlock = qemuVMDriverUnlock, -}; - int qemuRegister(void) { virRegisterDriver(&qemuDriver); virRegisterStateDriver(&qemuStateDriver); - virNWFilterRegisterCallbackDriver(&qemuCallbackDriver); return 0; } diff --git a/src/uml/uml_driver.c b/src/uml/uml_driver.c index a4a9258..91698e1 100644 --- a/src/uml/uml_driver.c +++ b/src/uml/uml_driver.c @@ -146,6 +146,34 @@ static int umlMonitorCommand(const struct uml_driver *driver, static struct uml_driver *uml_driver = NULL; +static int +umlVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, + virHashIterator iter, void *data) +{ + virHashForEach(uml_driver->domains.objs, iter, data); + + return 0; +} + +static void +umlVMDriverLock(void) +{ + umlDriverLock(uml_driver); +} + +static void +umlVMDriverUnlock(void) +{ + umlDriverUnlock(uml_driver); +} + +static virNWFilterCallbackDriver umlCallbackDriver = { + .name = "UML", + .vmFilterRebuild = umlVMFilterRebuild, + .vmDriverLock = umlVMDriverLock, + .vmDriverUnlock = umlVMDriverUnlock, +}; + struct umlAutostartData { struct uml_driver *driver; virConnectPtr conn; @@ -505,6 +533,7 @@ umlStartup(int privileged) VIR_FREE(userdir); + virNWFilterRegisterCallbackDriver(&umlCallbackDriver); return 0; out_of_memory: @@ -603,6 +632,7 @@ umlShutdown(void) { return -1; umlDriverLock(uml_driver); + virNWFilterRegisterCallbackDriver(&umlCallbackDriver); if (uml_driver->inotifyWatch != -1) virEventRemoveHandle(uml_driver->inotifyWatch); VIR_FORCE_CLOSE(uml_driver->inotifyFD); @@ -2596,15 +2626,6 @@ static virDriver umlDriver = { .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */ }; -static int -umlVMFilterRebuild(virConnectPtr conn ATTRIBUTE_UNUSED, - virHashIterator iter, void *data) -{ - virHashForEach(uml_driver->domains.objs, iter, data); - - return 0; -} - static virStateDriver umlStateDriver = { .name = "UML", .initialize = umlStartup, @@ -2613,28 +2634,8 @@ static virStateDriver umlStateDriver = { .active = umlActive, }; -static void -umlVMDriverLock(void) -{ - umlDriverLock(uml_driver); -} - -static void -umlVMDriverUnlock(void) -{ - umlDriverUnlock(uml_driver); -} - -static virNWFilterCallbackDriver umlCallbackDriver = { - .name = "UML", - .vmFilterRebuild = umlVMFilterRebuild, - .vmDriverLock = umlVMDriverLock, - .vmDriverUnlock = umlVMDriverUnlock, -}; - int umlRegister(void) { virRegisterDriver(&umlDriver); virRegisterStateDriver(&umlStateDriver); - virNWFilterRegisterCallbackDriver(&umlCallbackDriver); return 0; } -- 1.7.11.2

On 08/09/2012 04:08 PM, Eric Blake wrote: Okay. it's not going to make any practical difference, but just to give the appearance of being optimized, I squashed in the following before pushing: diff --git a/src/conf/nwfilter_conf.c b/src/conf/nwfilter_conf.c index 4fbbc78..8f8e053 100644 --- a/src/conf/nwfilter_conf.c +++ b/src/conf/nwfilter_conf.c @@ -2837,10 +2837,8 @@ virNWFilterUnRegisterCallbackDriver(virNWFilterCallbackDriverPtr cbd) i++; if (i < nCallbackDriver) { - while (i < nCallbackDriver - 1) { - callbackDrvArray[i] = callbackDrvArray[i+1]; - i++; - } + memmove(&callbackDrvArray[i], &callbackDrvArray[i+1], + (nCallbackDriver - i - 1) * sizeof(callbackDrvArray[i])); callbackDrvArray[i] = 0; nCallbackDriver--; } I couldn't decide whether or not to be case sensitive when adding this entry, but the thought at the top of my mind was "I'm *sure* Eric will say something about this!" :-) Thanks for the review. I squashed in the bit above and pushed it.