On Tue, Jun 12, 2018 at 01:47:00PM +0800, Peter Xu wrote: > On Mon, Jun 11, 2018 at 05:45:49PM +0100, Stefan Hajnoczi wrote: > > On Fri, Jun 08, 2018 at 10:18:25AM +0200, Markus Armbruster wrote: > > > Stefan Hajnoczi <stefa...@gmail.com> writes: > > > > On Fri, Jun 08, 2018 at 12:42:35PM +0800, Peter Xu wrote: > > > >> On Thu, Jun 07, 2018 at 01:53:01PM +0200, Markus Armbruster wrote: > > > >> > Peter Xu <pet...@redhat.com> writes: > > > >> > > > > >> > > Previously we cleanup the queues when we got CLOSED event. It was > > > >> > > used > > > >> > > > > >> > we clean up > > > >> > > > > >> > > to make sure we won't leftover replies/events of a old client to a > > > >> > > new > > > >> > > > > >> > we won't send leftover replies/events of an old client > > > >> > > > > >> > > client. Now this patch postpones that until OPENED. > > > >> > > > > >> > What if OPENED never comes? > > > >> > > > >> Then we clean that up until destruction of the monitor. IMHO it's > > > >> fine, but I'm not sure whether that's an overall acceptable approach. > > > > > > > > I think this patch fixes the problem at the wrong level. Marc-André's > > > > fix seemed like a cleaner solution. > > > > > > Is it the right solution? > > > > > > I proposed another one: > > > > Sorry, I won't be able to participate in this because I'm behind on > > other patches and tasks. Therefore, feel free to disregard but I'll > > give my 2 cents: > > > > This seems like a chardev bug. The solution should probably be in the > > chardev layer (Marc-André's patch or something else), not in the monitor > > (this patch). > > Yes that's why I said I like Marc-Andre's patch. :) I just don't know > an reliable way to achieve what we want there. > > The thing is that we don't really monitor the ioc_out for fd-typed > chardevs. We only do that when we call qemu_chr_fe_add_watch() (e.g., > in monitor_flush_locked()) when the writting buffer is full. But > normally we can't detect any event from the output side, hence no way > to deliever a CLOSED event when the output fd is the last fd that is > closed. > > Maybe we can keep that output watch for the whole lifecycle of the > chardev? I'm not sure yet.
It's not possible to keep a POLLOUT fd watch since poll(2) would return instantly and the event loop would spin. However, POLLHUP (G_IO_HUP) might work. Stefan
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