Re: [RFC PATCH 0/4] aio: AIO_CONTEXT_ACQUIRE_GUARD() macro experiment

[Stefan Hajnoczi]

On Tue, Oct 05, 2021 at 08:58:03PM +0200, Philippe Mathieu-Daudé wrote:
> Experiment to use glib g_autoptr/autofree features with
> AIO context.
> Since this is a RFC, only few examples are provided.
> 
> TODO: Document the macros in docs/devel/multiple-iothreads.txt
> 
> Philippe Mathieu-Daudé (4):
>   block/aio: Add automatically released aio_context variants
>   hw/scsi/scsi-disk: Use automatic AIO context lock
>   hw/scsi/scsi-generic: Use automatic AIO context lock
>   hw/block/virtio-blk: Use automatic AIO context lock
> 
>  include/block/aio.h    | 24 ++++++++++++++++++++++++
>  hw/block/virtio-blk.c  | 26 ++++++++++++--------------
>  hw/scsi/scsi-disk.c    | 13 ++++---------
>  hw/scsi/scsi-generic.c |  6 +++---
>  4 files changed, 43 insertions(+), 26 deletions(-)

This is nice. Two things:

1. Emanuele is working on eliminating aio_context_acquire/release(), so
   a big effort to convert existing code to using guards could be wasted
   energy and cause conflicts with his patches.

2. A few callers anticipate that the AioContext of their BDS may change
   between acquire/release. Care needs to be taken when converting to
   preserve the semantics but most instances should be safe to convert.

Stefan

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