Re: [libvirt] [PATCH 01/21] qemu_hotplug: remove erroneous call to qemuDomainDetachExtensionDevice()

qemuDomainDetachControllerDevice() calls qemuDomainDetachExtensionDevice() when the *controller* type is PCI. This is incorrect in multiple ways: * Any code that tears down a device should be in the qemuDomainRemove*Device() function (which is called after libvirt gets a DEVICE_DELETED event from qemu indicating that the guest is finished with the device on its end. The qemuDomainDetach*Device() functions should only contain code that ensures the requested operation is valid, and sends the command to qemu to initiate the unplug. * qemuDomainDetachExtensionDevice() is a function that applies to devices that plug into a PCI slot, *not* necessarily PCI controllers (which is what's being checked in the offending code). The proper way to check for this would be to see if the DeviceInfo for the controller device had a PCI address, not to check if the controller is a PCI controller (the code being removed was doing the latter). * According to commit 1d1e264f1 that added this code (and other support for hotplugging zPCI devices on s390), it's not necessary to explicitly detach the zPCI device when unplugging a PCI device. To quote: There's no need to implement hot unplug for zPCI as QEMU implements an unplug callback which will unplug both PCI and zPCI device in a cascaded way. and the evidence bears this out - all the other uses of qemuDomainDetachExtensionDevice() (except one, which I believe is also in error, and is being removed in a separate patch) are only to remove the zPCI extension device in cases where it was successfully added, but there was some other failure later in the hotplug process (so there was no regular PCI device to remove and trigger removal of the zPCI extension device). * PCI controllers are not hot pluggable, so this is dead code

anyway. (The only controllers that can currently be hotplugged/unplugged are SCSI controllers). Signed-off-by: Laine Stump <laine(a)laine.org&gt; --- src/qemu/qemu_hotplug.c | 12 ------------ 1 file changed, 12 deletions(-)