Re: [libvirt] [PATCH] esx: Improve blocked task detection and fix race condition

esxVI_WaitForTaskCompletion can take a UUID to lookup the corresponding domain and check if the current task for it is blocked by a question. It calls another function to do this: esxVI_LookupAndHandleVirtualMachineQuestion looks up the VirtualMachine and checks for a question. If there is a question it calls esxVI_HandleVirtualMachineQuestion to handle it. If there was no question or it has been answered the call to esxVI_LookupAndHandleVirtualMachineQuestion returns 0. If any error occurred during the lookup and answering process -1 is returned. The problem with this is, that -1 is also returned when there was no error but the question could not be answered. So esxVI_WaitForTaskCompletion cannot distinguish between this two situations and reports that a question is blocking the task even when there was actually another problem. This inherent problem didn't surface until vSphere 4.1 when you try to define a new domain. The driver tries to lookup the domain that is just in the process of being registered. There seems to be some kind of race condition and the driver manages to issue a lookup command before the ESX server was able to register the domain. This used to work before. Due to the return value problem described above the driver reported a false error message in that case. To solve this esxVI_WaitForTaskCompletion now takes an additional occurrence parameter that describes whether or not to expect the domain to be existent. Also add a new parameter to esxVI_LookupAndHandleVirtualMachineQuestion that allows to distinguish if the call returned -1 because of an actual error or because the question could not be answered. --- src/esx/esx_driver.c | 17 ++++++++++++++- src/esx/esx_vi.c | 53 ++++++++++++++++++++++++++++++++++++------------- src/esx/esx_vi.h | 7 ++++- src/esx/esx_vmx.c | 4 +- 4 files changed, 61 insertions(+), 20 deletions(-)