On Wed, Nov 29, 2023 at 02:55:44PM -0500, Stefan Hajnoczi wrote:
> aio_context_acquire()/aio_context_release() has been replaced by
> fine-grained locking to protect state shared by multiple threads. The
> AioContext lock still plays the role of balancing locking in
> AIO_WAIT_WHILE() and many functions in QEMU either require that the
> AioContext lock is held or not held for this reason. In other words, the
> AioContext lock is purely there for consistency with itself and serves
> no real purpose anymore.
>
> Stop actually acquiring/releasing the lock in
> aio_context_acquire()/aio_context_release() so that subsequent patches
> can remove callers across the codebase incrementally.
>
> I have performed "make check" and qemu-iotests stress tests across
> x86-64, ppc64le, and aarch64 to confirm that there are no failures as a
> result of eliminating the lock.
>
> Signed-off-by: Stefan Hajnoczi
> ---
> util/async.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/util/async.c b/util/async.c
> index 8f90ddc304..04ee83d220 100644
> --- a/util/async.c
> +++ b/util/async.c
> @@ -725,12 +725,12 @@ void aio_context_unref(AioContext *ctx)
>
> void aio_context_acquire(AioContext *ctx)
> {
> -qemu_rec_mutex_lock(>lock);
> +/* TODO remove this function */
> }
>
> void aio_context_release(AioContext *ctx)
> {
> -qemu_rec_mutex_unlock(>lock);
> +/* TODO remove this function */
> }
>
> QEMU_DEFINE_STATIC_CO_TLS(AioContext *, my_aiocontext)
> --
> 2.42.0
Reviewed-by: Eric Blake
--
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization: qemu.org | libguestfs.org
