Re: [PATCH v4 05/11] block-coroutine-wrapper.py: default to main loop aiocontext if function does not have a BlockDriverState parameter

[Kevin Wolf]

Am 21.11.2022 um 16:52 hat Emanuele Giuseppe Esposito geschrieben:
> Am 21/11/2022 um 16:30 schrieb Kevin Wolf:
> > Am 16.11.2022 um 13:22 hat Emanuele Giuseppe Esposito geschrieben:
> >> Basically BdrvPollCo->bs is only used by bdrv_poll_co(), and the
> >> functions that it uses are both using bdrv_get_aio_context, that
> >> defaults to qemu_get_aio_context() if bs is NULL.
> >>
> >> Therefore pass NULL to BdrvPollCo to automatically generate a function
> >> that create and runs a coroutine in the main loop.
> >>
> >> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> > 
> > It happens to work, but it's kind of ugly to call bdrv_coroutine_enter()
> > and BDRV_POLL_WHILE() with a NULL bs.
> > 
> > How hard would it be to generate code that doesn't use these functions,
> > but directly aio_co_enter() and AIO_WAIT_WHILE() for wrappers that are
> > not related to a BDS?
> > 
> 
> At this point, I would get rid of s->poll_state.bs and instead use
> s->poll_state.aio_context. Then call directly aio_co_enter and
> AIO_WAIT_WHILE, as you suggested but just everywhere, without
> differentiating the cases.

Oh, yes, that's better.

> Then we would have something similar to what it is currently done with bs:
> 
> if t == 'BlockDriverState *':
>             bs = 'bdrv_get_aio_context(bs)'
>         elif t == 'BdrvChild *':
>             bs = 'bdrv_get_aio_context(child->bs)'
>         elif t == 'BlockBackend *':
>             bs = 'bdrv_get_aio_context(blk_bs(blk))'

blk_get_aio_context(blk) seems more correct.

>         else:
>             bs = 'qemu_get_aio_context()'
> 
> I haven't tried it yet, but it should work.

Kevin