[libvirt] [PATCH] nwfilter: Handle libvirtd restart if nwfilter binding deleted
https://bugzilla.redhat.com/show_bug.cgi?id=1607202 It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing. So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on. Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-) diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c index f39c8a1f9b..3e6e462def 100644 --- a/src/conf/domain_nwfilter.c +++ b/src/conf/domain_nwfilter.c @@ -85,16 +85,19 @@ int virDomainConfNWFilterInstantiate(const char *vmname, const unsigned char *vmuuid, virDomainNetDefPtr net, - bool ignoreExists) + bool ignoreExists, + bool ignoreDeleted) { virConnectPtr conn = virGetConnectNWFilter(); virNWFilterBindingDefPtr def = NULL; virNWFilterBindingPtr binding = NULL; + virNWFilterPtr nwfilter = NULL; char *xml = NULL; int ret = -1; - VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d", - vmname, NULLSTR(net->ifname), NULLSTR(net->filter), ignoreExists); + VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d ignoreDeleted=%d", + vmname, NULLSTR(net->ifname), NULLSTR(net->filter), + ignoreExists, ignoreDeleted); if (!conn) goto cleanup; @@ -113,14 +116,34 @@ virDomainConfNWFilterInstantiate(const char *vmname, if (!(xml = virNWFilterBindingDefFormat(def))) goto cleanup; - if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) - goto cleanup; + if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) { + virErrorPtr orig_err; + + if (!ignoreDeleted) + goto cleanup; + + /* Let's determine if the error was because the filter was deleted. + * Save the orig_err just in case it's not a failure to find the + * filter by name. */ + orig_err = virSaveLastError(); + nwfilter = virNWFilterLookupByName(conn, def->filter); + virSetError(orig_err); + virFreeError(orig_err); + if (nwfilter) + goto cleanup; + + VIR_WARN("filter '%s' for binding '%s' has been deleted while the " + "guest was running, ignoring for restart processing", + def->filter, def->portdevname); + virResetLastError(); + } ret = 0; cleanup: VIR_FREE(xml); virNWFilterBindingDefFree(def); + virObjectUnref(nwfilter); virObjectUnref(binding); virObjectUnref(conn); return ret; diff --git a/src/conf/domain_nwfilter.h b/src/conf/domain_nwfilter.h index 6bda228fc8..e3a2f7a7f2 100644 --- a/src/conf/domain_nwfilter.h +++ b/src/conf/domain_nwfilter.h @@ -26,7 +26,8 @@ int virDomainConfNWFilterInstantiate(const char *vmname, const unsigned char *vmuuid, virDomainNetDefPtr net, - bool ignoreExists); + bool ignoreExists, + bool ignoreDeleted); void virDomainConfNWFilterTeardown(virDomainNetDefPtr net); void virDomainConfVMNWFilterTeardown(virDomainObjPtr vm); diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c index 33c806630b..b8b014ca72 100644 --- a/src/lxc/lxc_process.c +++ b/src/lxc/lxc_process.c @@ -303,7 +303,8 @@ virLXCProcessSetupInterfaceTap(virDomainDefPtr vm, } if (net->filter && - virDomainConfNWFilterInstantiate(vm->name, vm->uuid, net, false) < 0) + virDomainConfNWFilterInstantiate(vm->name, vm->uuid, net, + false, false) < 0) goto cleanup; ret = containerVeth; diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c index 0b84a503bb..11b10cbe14 100644 --- a/src/qemu/qemu_hotplug.c +++ b/src/qemu/qemu_hotplug.c @@ -3434,8 +3434,8 @@ qemuDomainChangeNetFilter(virDomainObjPtr vm, virDomainConfNWFilterTeardown(olddev); if (newdev->filter && - virDomainConfNWFilterInstantiate(vm->def->name, - vm->def->uuid, newdev, false) < 0) { + virDomainConfNWFilterInstantiate(vm->def->name, vm->def->uuid, newdev, + false, false) < 0) { virErrorPtr errobj; virReportError(VIR_ERR_OPERATION_FAILED, @@ -3444,7 +3444,8 @@ qemuDomainChangeNetFilter(virDomainObjPtr vm, olddev->ifname); virErrorPreserveLast(&errobj); ignore_value(virDomainConfNWFilterInstantiate(vm->def->name, - vm->def->uuid, olddev, false)); + vm->def->uuid, olddev, + false, false)); virErrorRestore(&errobj); return -1; } diff --git a/src/qemu/qemu_interface.c b/src/qemu/qemu_interface.c index a3f13093f5..fc5f39b76d 100644 --- a/src/qemu/qemu_interface.c +++ b/src/qemu/qemu_interface.c @@ -467,7 +467,8 @@ qemuInterfaceEthernetConnect(virDomainDefPtr def, goto cleanup; if (net->filter && - virDomainConfNWFilterInstantiate(def->name, def->uuid, net, false) < 0) { + virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + false, false) < 0) { goto cleanup; } @@ -586,7 +587,8 @@ qemuInterfaceBridgeConnect(virDomainDefPtr def, goto cleanup; if (net->filter && - virDomainConfNWFilterInstantiate(def->name, def->uuid, net, false) < 0) { + virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + false, false) < 0) { goto cleanup; } diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index ab749389ee..4d8b3017b4 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -3161,14 +3161,18 @@ qemuProcessNotifyNets(virDomainDefPtr def) } static int -qemuProcessFiltersInstantiate(virDomainDefPtr def, bool ignoreExists) +qemuProcessFiltersInstantiate(virDomainDefPtr def, + bool ignoreExists, + bool ignoreDeleted) { size_t i; for (i = 0; i < def->nnets; i++) { virDomainNetDefPtr net = def->nets[i]; if ((net->filter) && (net->ifname)) { - if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0) + if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + ignoreExists, + ignoreDeleted) < 0) return 1; } } @@ -7892,7 +7896,7 @@ qemuProcessReconnect(void *opaque) qemuProcessNotifyNets(obj->def); - if (qemuProcessFiltersInstantiate(obj->def, true)) + if (qemuProcessFiltersInstantiate(obj->def, true, true)) goto error; if (qemuProcessRefreshDisks(driver, obj, QEMU_ASYNC_JOB_NONE) < 0) diff --git a/src/uml/uml_conf.c b/src/uml/uml_conf.c index f116e619ef..29d26848f3 100644 --- a/src/uml/uml_conf.c +++ b/src/uml/uml_conf.c @@ -137,7 +137,8 @@ umlConnectTapDevice(virDomainDefPtr vm, } if (net->filter) { - if (virDomainConfNWFilterInstantiate(vm->name, vm->uuid, net, false) < 0) { + if (virDomainConfNWFilterInstantiate(vm->name, vm->uuid, net, + false, false) < 0) { if (template_ifname) VIR_FREE(net->ifname); goto error; -- 2.17.1
On Wed, Aug 22, 2018 at 05:43:21PM -0400, John Ferlan wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1607202
It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing.
So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on.
Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-)
diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c index f39c8a1f9b..3e6e462def 100644 --- a/src/conf/domain_nwfilter.c +++ b/src/conf/domain_nwfilter.c @@ -85,16 +85,19 @@ int virDomainConfNWFilterInstantiate(const char *vmname, const unsigned char *vmuuid, virDomainNetDefPtr net, - bool ignoreExists) + bool ignoreExists, + bool ignoreDeleted) { virConnectPtr conn = virGetConnectNWFilter(); virNWFilterBindingDefPtr def = NULL; virNWFilterBindingPtr binding = NULL; + virNWFilterPtr nwfilter = NULL; char *xml = NULL; int ret = -1;
- VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d", - vmname, NULLSTR(net->ifname), NULLSTR(net->filter), ignoreExists); + VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d ignoreDeleted=%d", + vmname, NULLSTR(net->ifname), NULLSTR(net->filter), + ignoreExists, ignoreDeleted);
if (!conn) goto cleanup; @@ -113,14 +116,34 @@ virDomainConfNWFilterInstantiate(const char *vmname, if (!(xml = virNWFilterBindingDefFormat(def))) goto cleanup;
- if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) - goto cleanup; + if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) { + virErrorPtr orig_err; + + if (!ignoreDeleted) + goto cleanup; + + /* Let's determine if the error was because the filter was deleted. + * Save the orig_err just in case it's not a failure to find the + * filter by name. */ + orig_err = virSaveLastError(); + nwfilter = virNWFilterLookupByName(conn, def->filter); + virSetError(orig_err); + virFreeError(orig_err); + if (nwfilter) + goto cleanup; + + VIR_WARN("filter '%s' for binding '%s' has been deleted while the " + "guest was running, ignoring for restart processing", + def->filter, def->portdevname); + virResetLastError(); + }
I don't get what this code is trying to do. This method is about creating nwfilter bindings. If virNWFilterBindingCreateXML() fails, that means the filter binding already exists. But the stated problem was that the admin had deleted the filter binding. The code is also checking a filter, not a filter binding. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 08/23/2018 03:44 AM, Daniel P. Berrangé wrote:
On Wed, Aug 22, 2018 at 05:43:21PM -0400, John Ferlan wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1607202
It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing.
So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on.
Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-)
diff --git a/src/conf/domain_nwfilter.c b/src/conf/domain_nwfilter.c index f39c8a1f9b..3e6e462def 100644 --- a/src/conf/domain_nwfilter.c +++ b/src/conf/domain_nwfilter.c @@ -85,16 +85,19 @@ int virDomainConfNWFilterInstantiate(const char *vmname, const unsigned char *vmuuid, virDomainNetDefPtr net, - bool ignoreExists) + bool ignoreExists, + bool ignoreDeleted) { virConnectPtr conn = virGetConnectNWFilter(); virNWFilterBindingDefPtr def = NULL; virNWFilterBindingPtr binding = NULL; + virNWFilterPtr nwfilter = NULL; char *xml = NULL; int ret = -1;
- VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d", - vmname, NULLSTR(net->ifname), NULLSTR(net->filter), ignoreExists); + VIR_DEBUG("vmname=%s portdev=%s filter=%s ignoreExists=%d ignoreDeleted=%d", + vmname, NULLSTR(net->ifname), NULLSTR(net->filter), + ignoreExists, ignoreDeleted);
if (!conn) goto cleanup; @@ -113,14 +116,34 @@ virDomainConfNWFilterInstantiate(const char *vmname, if (!(xml = virNWFilterBindingDefFormat(def))) goto cleanup;
- if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) - goto cleanup; + if (!(binding = virNWFilterBindingCreateXML(conn, xml, 0))) { + virErrorPtr orig_err; + + if (!ignoreDeleted) + goto cleanup; + + /* Let's determine if the error was because the filter was deleted. + * Save the orig_err just in case it's not a failure to find the + * filter by name. */ + orig_err = virSaveLastError(); + nwfilter = virNWFilterLookupByName(conn, def->filter); + virSetError(orig_err); + virFreeError(orig_err); + if (nwfilter) + goto cleanup; + + VIR_WARN("filter '%s' for binding '%s' has been deleted while the " + "guest was running, ignoring for restart processing", + def->filter, def->portdevname); + virResetLastError(); + }
I don't get what this code is trying to do. This method is about creating nwfilter bindings. If virNWFilterBindingCreateXML() fails, that means the filter binding already exists. But the stated problem was that the admin had deleted the filter binding. The code is also checking a filter, not a filter binding.
virNWFilterBindingCreateXML eventually calls nwfilterBindingCreateXML, which will virNWFilterBindingObjListAdd the binding, get the @ret binding and attempt to virNWFilterInstantiateFilter the binding @def. Instantiate will call virNWFilterInstantiateFilterInternal which calls virNWFilterInstantiateFilterUpdate (eventually) which calls virNWFilterObjListFindInstantiateFilter because someone deleted the filter after deleting the portdev before hand. As the bz shows, one cannot delete the filter because it's active in the portdev; however, deleting the portdev allows one to delete the filter. Once the port is deleted, the 'ebtables -t nat -L' will show it's gone. Attempting to create the portdev again when libvirtd restarts (because virDomainConfNWFilterInstantiate is called during that processing) will cause a failure and the guest will be stopped. Prior to the changes, adding a debug print in nwfilterBindingCreateXML of the XML I see the following in a debug libvirtd session restart: Detaching after fork from child process 13163. 2018-08-22 17:08:58.878+0000: 13162: warning : nwfilterBindingCreateXML:748 : xml=<filterbinding> <owner> <name>f23</name> <uuid>43dc0cf8-809b-4adb-9bea-a9abb5f3d90e</uuid> </owner> <portdev name='vnet0'/> <mac address='52:54:00:f7:d4:f7'/> <filterref filter='clean-traffic'/> </filterbinding> 2018-08-22 17:08:58.878+0000: 13162: error : virNWFilterObjListFindInstantiateFilter:201 : internal error: referenced filter 'clean-traffic' is missing ... One finds the guest shutdown, the subsequent start would also fail: [Thread 0x7fffa7fff700 (LWP 13083) exited] 2018-08-22 17:16:33.035+0000: 13068: warning : nwfilterBindingCreateXML:748 : xml=<filterbinding> <owner> <name>f23</name> <uuid>43dc0cf8-809b-4adb-9bea-a9abb5f3d90e</uuid> </owner> <portdev name='vnet0'/> <mac address='52:54:00:f7:d4:f7'/> <filterref filter='clean-traffic'/> </filterbinding> 2018-08-22 17:16:33.036+0000: 13068: error : virNWFilterObjListFindInstantiateFilter:201 : internal error: referenced filter 'clean-traffic' is missing 2018-08-22 17:16:33.065+0000: 13157: error : virFileReadAll:1435 : Failed to open file '/sys/class/net/vnet0/operstate': No such file or directory 2018-08-22 17:16:33.065+0000: 13157: error : virNetDevGetLinkInfo:2559 : unable to read: /sys/class/net/vnet0/operstate: No such file or directory .... With the patch in place, I'll now get: Detaching after fork from child process 6919. 2018-08-22 21:29:45.201+0000: 6918: error : virNWFilterObjListFindInstantiateFilter:201 : internal error: referenced filter 'clean-traffic' is missing 2018-08-22 21:29:45.201+0000: 6918: warning : virDomainConfNWFilterInstantiate:135 : filter 'clean-traffic' for binding 'vnet0' has been deleted while the guest was running, ignoring for restart processing [Thread 0x7fff9dffb700 (LWP 6918) exited] .... After restarting libvirtd, I can define the filter again and use the *CreateXML API in order to reinstate the filter for the guest as shown in the ebtables output. And yes, I understand/agree that if some admin ends up using the virNWFilterBindingDelete API they are on their own, but I think the shutdown would be unexpected. Another "option" I considered was to alter the live XML to remove the net->filter so that a subsequent libvirtd restart wouldn't fail. That may be accomplish-able via some @flag usage for the *Delete API to know the call didn't come from the hypervisor induced call, but I wasn't sure if it was "fail safe" and altering the live XML for the guest has it's own drawbacks/failures that would need to be handled. John
On Wed, Aug 22, 2018 at 05:43:21PM -0400, John Ferlan wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1607202
It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain
So based on your explanation in the other reply, this message is what was misleading me. s/nwfilter binding/nwfilter/
is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing.
So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on.
Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-)
[snip]
static int -qemuProcessFiltersInstantiate(virDomainDefPtr def, bool ignoreExists) +qemuProcessFiltersInstantiate(virDomainDefPtr def, + bool ignoreExists, + bool ignoreDeleted) { size_t i;
for (i = 0; i < def->nnets; i++) { virDomainNetDefPtr net = def->nets[i]; if ((net->filter) && (net->ifname)) { - if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0) + if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + ignoreExists, + ignoreDeleted) < 0) return 1; }
Rather than this extra "ignoreDeleted" arg, why can't we just do if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0 && ignoreDeleted) return 1; This ensures that all things which can cause a nwfilter binding failure on startup will be handled by avoiding tearing down the running guest. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 08/23/2018 07:27 AM, Daniel P. Berrangé wrote:
On Wed, Aug 22, 2018 at 05:43:21PM -0400, John Ferlan wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1607202
It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain
So based on your explanation in the other reply, this message is what was misleading me. s/nwfilter binding/nwfilter/
Actually perhaps it's more by "first removing the nwfilter binding and subsequently undefining the nwfilter that is/was in use for the running guest..." If just the nwfilter binding was removed, then libvirtd restart would have been fine because it would have recreated the nwfilter binding. Of course that may not be expected either...
is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing.
So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on.
Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-)
[snip]
static int -qemuProcessFiltersInstantiate(virDomainDefPtr def, bool ignoreExists) +qemuProcessFiltersInstantiate(virDomainDefPtr def, + bool ignoreExists, + bool ignoreDeleted) { size_t i;
for (i = 0; i < def->nnets; i++) { virDomainNetDefPtr net = def->nets[i]; if ((net->filter) && (net->ifname)) { - if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0) + if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + ignoreExists, + ignoreDeleted) < 0) return 1; }
Rather than this extra "ignoreDeleted" arg, why can't we just do
if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0 && ignoreDeleted) return 1;
This ensures that all things which can cause a nwfilter binding failure on startup will be handled by avoiding tearing down the running guest.
Did you mean !ignoreDeleted? There's only one caller to qemuProcessFiltersInstantiate which does: if (qemuProcessFiltersInstantiate(obj->def, true)) goto error; Of course what's the purpose of distinguishing between ignoreExists and ignoreDeleted then? Essentially what you're indicating is we wouldn't care about any error because virDomainConfNWFilterInstantiate wouldn't be distinguishing between any error (because there's only one caller to qemuProcessFiltersInstantiate). I could change the last argument to virDomainConfNWFilterInstantiate to be a flag instead of a bool so that if we have future errors we care to ignore we don't keep adding bool arguments, but that's just a implementation detail. Again, I could go back and figure out a way for the *Delete path to remove the live net->filter based on the path taken so that when we get here we wouldn't find the net->filter and thus wouldn't call the instantiate function. It's just a different approach, but I'm hesitant mainly because then one wouldn't be able to use the *CreateXML API to reinstate the filter. I'm not as clear about all the (wacko) use cases. John
On Thu, Aug 23, 2018 at 07:59:41AM -0400, John Ferlan wrote:
On 08/23/2018 07:27 AM, Daniel P. Berrangé wrote:
On Wed, Aug 22, 2018 at 05:43:21PM -0400, John Ferlan wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1607202
It's stated that if the admin wants to shoot themselves in the foot by removing the nwfilter binding while the domain
So based on your explanation in the other reply, this message is what was misleading me. s/nwfilter binding/nwfilter/
Actually perhaps it's more by "first removing the nwfilter binding and subsequently undefining the nwfilter that is/was in use for the running guest..."
If just the nwfilter binding was removed, then libvirtd restart would have been fine because it would have recreated the nwfilter binding. Of course that may not be expected either...
is running we will certainly allow that. However, in doing so we also run the risk that a libvirtd restart will cause the domain to be shutdown, which isn't a good thing.
So add another boolean to virDomainConfNWFilterInstantiate which allows us to recover somewhat gracefully in the event the virNWFilterBindingCreateXML fails when we come from qemuProcessReconnect and we determine that the filter has been deleted. It was there at some point (it had to be), but if it's missing, then we don't want to cause the guest to stop running, so issue a warning and continue on.
Signed-off-by: John Ferlan <jferlan@redhat.com> --- src/conf/domain_nwfilter.c | 33 ++++++++++++++++++++++++++++----- src/conf/domain_nwfilter.h | 3 ++- src/lxc/lxc_process.c | 3 ++- src/qemu/qemu_hotplug.c | 7 ++++--- src/qemu/qemu_interface.c | 6 ++++-- src/qemu/qemu_process.c | 10 +++++++--- src/uml/uml_conf.c | 3 ++- 7 files changed, 49 insertions(+), 16 deletions(-)
[snip]
static int -qemuProcessFiltersInstantiate(virDomainDefPtr def, bool ignoreExists) +qemuProcessFiltersInstantiate(virDomainDefPtr def, + bool ignoreExists, + bool ignoreDeleted) { size_t i;
for (i = 0; i < def->nnets; i++) { virDomainNetDefPtr net = def->nets[i]; if ((net->filter) && (net->ifname)) { - if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0) + if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, + ignoreExists, + ignoreDeleted) < 0) return 1; }
Rather than this extra "ignoreDeleted" arg, why can't we just do
if (virDomainConfNWFilterInstantiate(def->name, def->uuid, net, ignoreExists) < 0 && ignoreDeleted) return 1;
This ensures that all things which can cause a nwfilter binding failure on startup will be handled by avoiding tearing down the running guest.
Did you mean !ignoreDeleted? There's only one caller to
Heh, yes.
qemuProcessFiltersInstantiate which does:
if (qemuProcessFiltersInstantiate(obj->def, true)) goto error;
Of course what's the purpose of distinguishing between ignoreExists and ignoreDeleted then? Essentially what you're indicating is we wouldn't care about any error because virDomainConfNWFilterInstantiate wouldn't be distinguishing between any error (because there's only one caller to qemuProcessFiltersInstantiate).
Oh thats a good point - I forgot ignoreExists was for the same reason.
I could change the last argument to virDomainConfNWFilterInstantiate to be a flag instead of a bool so that if we have future errors we care to ignore we don't keep adding bool arguments, but that's just a implementation detail.
We've deal with 1 problem scenario (alredy existing binding) and now adding a second (missing filter). Will someone find a third scenario and then a fourth. The flags argument ends up effectively being a bitmask of lines where we ignore errors. I'm wondering is it *ever* valid to treat failure of this filter call as a fatal problem and teardown an already running VM ? My gut says no. So perhaps we remove the ignoreExists parameter too, and just make that one caller simply ignore the errors on restarts. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
participants (2)
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Daniel P. Berrangé -
John Ferlan