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

From: Kevin Wolf <kwolf@redhat.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Cc: qemu-block@nongnu.org, Hanna Reitz <hreitz@redhat.com>,
	John Snow <jsnow@redhat.com>,
	Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>,
	Eric Blake <eblake@redhat.com>, Fam Zheng <fam@euphon.net>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH v4 05/11] block-coroutine-wrapper.py: default to main loop aiocontext if function does not have a BlockDriverState parameter
Date: Mon, 21 Nov 2022 16:30:04 +0100	[thread overview]
Message-ID: <Y3uZfAWotAr9IMGe@redhat.com> (raw)
In-Reply-To: <20221116122241.2856527-6-eesposit@redhat.com>

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?

Kevin