Re: [libvirt] [PATCH 4/4] qemu: hot-unplug of watchdog

On 09/12/2017 04:29 PM, John Ferlan wrote: > > > On 09/05/2017 07:45 AM, Michal Privoznik wrote: >> https://bugzilla.redhat.com/show_bug.cgi?id=1447169 >> >> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >> --- >> src/qemu/qemu_driver.c | 4 +- >> src/qemu/qemu_hotplug.c | 61 ++++++++++++++++++++++ >> src/qemu/qemu_hotplug.h | 3 ++ >> tests/qemuhotplugtest.c | 7 ++- >> .../qemuhotplug-watchdog-full.xml | 3 ++ >> 5 files changed, 76 insertions(+), 2 deletions(-) >> create mode 100644 tests/qemuhotplugtestdevices/qemuhotplug-watchdog-full.xml >> >> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c >> index 626148dba..4c636b956 100644 >> --- a/src/qemu/qemu_driver.c >> +++ b/src/qemu/qemu_driver.c >> @@ -7692,12 +7692,14 @@ qemuDomainDetachDeviceLive(virDomainObjPtr vm, >> case VIR_DOMAIN_DEVICE_SHMEM: >> ret = qemuDomainDetachShmemDevice(driver, vm, dev->data.shmem); >> break; >> + case VIR_DOMAIN_DEVICE_WATCHDOG: >> + ret = qemuDomainDetachWatchdog(driver, vm, dev->data.watchdog); >> + break; >> >> case VIR_DOMAIN_DEVICE_FS: >> case VIR_DOMAIN_DEVICE_INPUT: >> case VIR_DOMAIN_DEVICE_SOUND: >> case VIR_DOMAIN_DEVICE_VIDEO: >> - case VIR_DOMAIN_DEVICE_WATCHDOG: >> case VIR_DOMAIN_DEVICE_GRAPHICS: >> case VIR_DOMAIN_DEVICE_HUB: >> case VIR_DOMAIN_DEVICE_SMARTCARD: >> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c >> index 989146eb9..44472ce9f 100644 >> --- a/src/qemu/qemu_hotplug.c >> +++ b/src/qemu/qemu_hotplug.c >> @@ -4360,6 +4360,25 @@ qemuDomainRemoveShmemDevice(virQEMUDriverPtr driver, >> } >> >> >> +static int >> +qemuDomainRemoveWatchdog(virQEMUDriverPtr driver, >> + virDomainObjPtr vm, >> + virDomainWatchdogDefPtr watchdog) >> +{ >> + virObjectEventPtr event = NULL; >> + >> + VIR_DEBUG("Removing watchdog %s from domain %p %s", > > Is "Removing watchdog watchdog0 from ..." a bit superfluous? > > Perhaps just "Removing '%s' from ..." > >> + watchdog->info.alias, vm, vm->def->name); >> + > > This would/could be the place for the virDomainAuditWatchdog for > "detach" too. > >> + event = virDomainEventDeviceRemovedNewFromObj(vm, watchdog->info.alias); >> + qemuDomainEventQueue(driver, event); >> + qemuDomainReleaseDeviceAddress(vm, &watchdog->info, NULL); >> + virDomainWatchdogDefFree(vm->def->watchdog); >> + vm->def->watchdog = NULL; >> + return 0; >> +} >> + >> + >> int >> qemuDomainRemoveDevice(virQEMUDriverPtr driver, >> virDomainObjPtr vm, >> @@ -5076,6 +5095,48 @@ qemuDomainDetachShmemDevice(virQEMUDriverPtr driver, >> } >> >> >> +int >> +qemuDomainDetachWatchdog(virQEMUDriverPtr driver, >> + virDomainObjPtr vm, >> + virDomainWatchdogDefPtr dev) >> +{ >> + int ret = -1; >> + virDomainWatchdogDefPtr watchdog; > > Why not watchdog = vm->def->watchdog; here? > >> + qemuDomainObjPrivatePtr priv = vm->privateData; >> + >> + /* While domains can have up to one watchdog, the one supplied by user > > s/by/by the/ > >> + * doesn't necessarily match the one domain has. Refuse to detach in such >> + * case. */ >> + if (!(vm->def->watchdog && >> + STREQ_NULLABLE(dev->info.alias, >> + vm->def->watchdog->info.alias))) { > > if (!watchdog || STRNEQ_NULLABLE(dev->info.alias, watchdog->info.alias)) > > Trying to think why NULLABLE would be necessary... So it seems it's > required that that input XML has the alias - something not quite right > with that... Is that so? We match devices based on their alias in a lot of places. Users are expected to pass the full device XML anyway. So it's up to us how we pick the right device to be detached. For instance, when detaching a vNIC we match MAC addresses and ignore the rest, since MAC identifies the device uniquely. So for instance, if the detach XML provided by user has <bandwidth/> set but the one in domain doesn't have it, we detach the device anyway. One can argue this is a buggy behaviour. But I just don't think we should care. There's a line we have to draw between protecting users from themselves and too complex and mostly useless code. So we've documented that users are supposed to pass the device XML as is in the domain XML.