Am 27.09.2012 14:57, schrieb Paolo Bonzini: > Il 27/09/2012 14:45, Kevin Wolf ha scritto: >> Am 27.09.2012 14:27, schrieb Paolo Bonzini: >>> Il 27/09/2012 14:18, Kevin Wolf ha scritto: >>>>>> >>>>>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> >>>> I think there's a problem with terminology at least. What does "paused" >>>> really mean? Is it that the job has been requested to pause, or that it >>>> has actually yielded and is inactive? >>>> >>>> The commit message seems to use the latter semantics (which I would >>>> consider the intuitive one), >>> >>> You mean this: "Paused jobs cannot be canceled without first resuming >>> them". I can add a specification, like "(even if the job actually has >>> not reached the sleeping point and thus is still running)". >> >> I actually meant "pause happens at the next sleeping point", which isn't >> unspecific at all. > > Hmm, there are two aspects: 1) when things stop running; 2) when the job > reports itself to be paused. The commit message describes (1) > precisely, and doesn't say anything about (2). That's too specific for > a commit message, but the header file describes it precisely.
Yes, I understood that, I just found it confusing that both were called "paused" in different contexts. > However, in the QMP documentation, the good comment for "bool paused;" > must be replicated in BlockJobInfo's "paused" member. > >>> From the QMP client's point of view it doesn't really matter, does it? >>> >>> - even after a job that writes to disk X has "really" paused, you cannot >>> read or write disk X. It's still owned by QEMU, it hasn't been flushed, >>> it may play games like lazy refcounts. >> >> I'm not sure about this one. Consider things like a built-in NBD server. >> Probably we'll find more cases in the future, where some monitor command >> might seem to be safe while a job is paused. > > Ok, that's a good point. I'll add a "busy" member to BlockJobInfo. Ok, thanks. Together with the comment from the bool paused field this should make pretty clear what clients would have to check for. Kevin
