Re: [PATCH v4 08/12] aio-posix: gracefully handle io_uring_queue_init() failure

[Kevin Wolf <kwolf@redhat.com>]

Am 10.09.2025 um 19:56 hat Stefan Hajnoczi geschrieben:
> io_uring may not be available at runtime due to system policies (e.g.
> the io_uring_disabled sysctl) or creation could fail due to file
> descriptor resource limits.
> 
> Handle failure scenarios as follows:
> 
> If another AioContext already has io_uring, then fail AioContext
> creation so that the aio_add_sqe() API is available uniformly from all
> QEMU threads. Otherwise fall back to epoll(7) if io_uring is
> unavailable.
> 
> Notes:
> - Update the comment about selecting the fastest fdmon implementation.
>   At this point it's not about speed anymore, it's about aio_add_sqe()
>   API availability.
> - Uppercase the error message when converting from error_report() to
>   error_setg_errno() for consistency (but there are instances of
>   lowercase in the codebase).
> - It's easier to move the #ifdefs from aio-posix.h to aio-posix.c.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>

> @@ -369,7 +370,7 @@ static const FDMonOps fdmon_io_uring_ops = {
>      .gsource_dispatch = fdmon_io_uring_gsource_dispatch,
>  };
>  
> -bool fdmon_io_uring_setup(AioContext *ctx)
> +void fdmon_io_uring_setup(AioContext *ctx, Error **errp)
>  {
>      int ret;

Same as in the previous patch, it would be more conventional to keep the
bool return code in addition to the Error **. Either way:

Reviewed-by: Kevin Wolf <kwolf@redhat.com>