Re: [PULL 09/14] qmp: Move dispatcher to a coroutine

["Volker Rümelin" <vr_qemu@t-online.de>]

> From: Kevin Wolf <kwolf@redhat.com>
>
> This moves the QMP dispatcher to a coroutine and runs all QMP command
> handlers that declare 'coroutine': true in coroutine context so they
> can avoid blocking the main loop while doing I/O or waiting for other
> events.
>
> For commands that are not declared safe to run in a coroutine, the
> dispatcher drops out of coroutine context by calling the QMP command
> handler from a bottom half.

Hi Kevin,

since commit 9ce44e2ce2 "qmp: Move dispatcher to a coroutine" I see the following error on Windows whenever I close the QEMU window or shut down the guest.

$ ./qemu-system-x86_64.exe -machine pc,accel=tcg -display gtk
**
ERROR:../qemu/util/aio-win32.c:337:aio_poll: assertion failed: (in_aio_context_home_thread(ctx))
Bail out! ERROR:../qemu/util/aio-win32.c:337:aio_poll: assertion failed: (in_aio_context_home_thread(ctx))

I wonder if you forgot to apply the changes to util/aio-posix.c to util/aio-win32.c too? This solves the problem on my Windows host. But I have to admit I don't know the code here.

With best regards,
Volker

> diff --git a/util/aio-posix.c b/util/aio-posix.c
> index 280f27bb99..30f5354b1e 100644
> --- a/util/aio-posix.c
> +++ b/util/aio-posix.c
> @@ -15,6 +15,7 @@
>  
>  #include "qemu/osdep.h"
>  #include "block/block.h"
> +#include "qemu/main-loop.h"
>  #include "qemu/rcu.h"
>  #include "qemu/rcu_queue.h"
>  #include "qemu/sockets.h"
> @@ -558,8 +559,13 @@ bool aio_poll(AioContext *ctx, bool blocking)
>       * There cannot be two concurrent aio_poll calls for the same AioContext (or
>       * an aio_poll concurrent with a GSource prepare/check/dispatch callback).
>       * We rely on this below to avoid slow locked accesses to ctx->notify_me.
> +     *
> +     * aio_poll() may only be called in the AioContext's thread. iohandler_ctx
> +     * is special in that it runs in the main thread, but that thread's context
> +     * is qemu_aio_context.
>       */
> -    assert(in_aio_context_home_thread(ctx));
> +    assert(in_aio_context_home_thread(ctx == iohandler_get_aio_context() ?
> +                                      qemu_get_aio_context() : ctx));
>  
>      qemu_lockcnt_inc(&ctx->list_lock);
>