Re: [Qemu-devel] [PATCH 05/16] io: make qio_channel_yield aware of AioContexts

[Daniel P. Berrange]

On Mon, Jan 16, 2017 at 08:47:28PM +0800, Fam Zheng wrote:
> On Mon, 01/16 13:24, Paolo Bonzini wrote:
> > 
> > 
> > On 16/01/2017 12:38, Fam Zheng wrote:
> > >> +void qio_channel_detach_aio_context(QIOChannel *ioc)
> > >> +{
> > >> +    ioc->read_coroutine = NULL;
> > >> +    ioc->write_coroutine = NULL;
> > >> +    qio_channel_set_aio_fd_handlers(ioc);
> > >> +    ioc->ctx = NULL;
> > >
> > > Why is qio_channel_set_aio_fd_handler not needed here?
> > 
> > Because there are no read_coroutine and write_coroutine anymore.  The
> > caller needs to schedule them on the right AioContext after calling
> > qio_channel_set_aio_context.  See nbd_client_attach_aio_context in the
> > next patch for an example.
> > 
> > >> -tests/test-char$(EXESUF): tests/test-char.o qemu-char.o qemu-timer.o 
> > >> $(test-util-obj-y) $(qtest-obj-y) $(test-io-obj-y)
> > >> +tests/test-char$(EXESUF): tests/test-char.o qemu-char.o qemu-timer.o 
> > >> $(test-util-obj-y) $(qtest-obj-y) $(test-io-obj-y) $(test-block-obj-y)
> > > 
> > > I guess this is a hint for moving coroutine code into a lower level 
> > > library like
> > > util.
> > 
> > Coroutine, or AioContext?  The reason for this is that io/ now uses
> > aio_co_wake.
> 
> Or both. It just feels a bit odd to see *char* depend on *block*, maybe 
> there're
> more such dependencies to come even outside tests/?
> 
> Not necessarily for this series, of course.

On the contrary, I think it should be in this series - we shouldn't
introduce a dependancy on the block layer from io layer.

Regards,
Daniel
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