Re: [libvirt] [PATCH 2/3] qemu: special error code in case of no job on cancel block job

On 09/07/2016 05:24 AM, Nikolay Shirokovskiy wrote: > Special error code helps gracefully handle race conditions on > blockjob cancelling. Consider for example pull backup. We want > to stop it and in the process we cancel blockjob for some of the > exported disks. But at the time this command reaches qemu blockjob > fail for some reason and cancel result and result of stopping > will be an error with quite unexpecte message - no such job (sort of). > Instead we can detect this race and treat as correct cancelling > and wait until fail event will arrive. Then we can report corect > error message with some details from qemu probably. > > Users of domainBlockJobAbort can be affected as -2 is new possible > return code. Not sure if I should stick to the original behaviour in > this case. > --- > src/qemu/qemu_monitor.c | 5 +++++ > src/qemu/qemu_monitor_json.c | 11 +++++++---- > 2 files changed, 12 insertions(+), 4 deletions(-) > I haven't looked forward to patch 3/3 yet, but perhaps it'd be better in the "caller" that cares to : if (qemu*() < 0) { virErrorPtr err = virGetLastError(); if (err && err->code == VIR_ERR_OPERATION_INVALID) { /* Do something specific */ } } Returning -2 alters virDomainBlockJobAbort expected return values and well that's probably not a good idea since we don't know if some caller has said (if virDomainBlockJobAbort() == -1) instead of <= -1