Re: [RFC PATCH] chardev: don't exit() straight away on C-a x

[Philippe Mathieu-Daudé]

On 10/18/21 16:02, Alex Bennée wrote:
> While there are a number of uses in the code-base of the exit(0)
> pattern it gets in the way of clean exit which can do all of it's
> house-keeping. In particular it was reported that you can crash
> plugins this way because TCG can still be running on other threads
> when the atexit callback is called.
> 
> Use qemu_system_shutdown_request() instead. I did a gentle rename of
> the runstate stub seeing as it now contains two functions.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Reported-by: Lukas Jünger <lukas.junger@greensocs.com>
> ---
>  chardev/char-mux.c                     | 3 ++-
>  stubs/{runstate-check.c => runstate.c} | 5 +++++
>  stubs/meson.build                      | 2 +-
>  3 files changed, 8 insertions(+), 2 deletions(-)
>  rename stubs/{runstate-check.c => runstate.c} (64%)
> 
> diff --git a/chardev/char-mux.c b/chardev/char-mux.c
> index ada0c6866f..a46897fcd5 100644
> --- a/chardev/char-mux.c
> +++ b/chardev/char-mux.c
> @@ -28,6 +28,7 @@
>  #include "qemu/option.h"
>  #include "chardev/char.h"
>  #include "sysemu/block-backend.h"
> +#include "sysemu/runstate.h"
>  #include "chardev-internal.h"
>  
>  /* MUX driver for serial I/O splitting */
> @@ -157,7 +158,7 @@ static int mux_proc_byte(Chardev *chr, MuxChardev *d, int 
> ch)
>              {
>                   const char *term =  "QEMU: Terminated\n\r";
>                   qemu_chr_write_all(chr, (uint8_t *)term, strlen(term));
> -                 exit(0);
> +                 qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
>                   break;
>              }
>          case 's':
> diff --git a/stubs/runstate-check.c b/stubs/runstate.c
> similarity index 64%
> rename from stubs/runstate-check.c
> rename to stubs/runstate.c
> index 2ccda2b70f..f47dbcd3e0 100644
> --- a/stubs/runstate-check.c
> +++ b/stubs/runstate.c
> @@ -5,3 +5,8 @@ bool runstate_check(RunState state)
>  {
>      return state == RUN_STATE_PRELAUNCH;
>  }
> +
> +void qemu_system_shutdown_request(ShutdownCause reason)
> +{
> +    return;
> +}

Hmm this isn't a stub anymore, this is the user-mode implementation.

I'd rather have some shared user/ or meanwhile duplicate it in
both bsd-user/linux-user (even if the implementation is empty)
instead of a stub.

> diff --git a/stubs/meson.build b/stubs/meson.build
> index f6aa3aa94f..8f6a9f17e5 100644
> --- a/stubs/meson.build
> +++ b/stubs/meson.build
> @@ -35,7 +35,7 @@ stub_ss.add(files('qtest.c'))
>  stub_ss.add(files('ram-block.c'))
>  stub_ss.add(files('ramfb.c'))
>  stub_ss.add(files('replay.c'))
> -stub_ss.add(files('runstate-check.c'))
> +stub_ss.add(files('runstate.c'))
>  stub_ss.add(files('sysbus.c'))
>  stub_ss.add(files('target-get-monitor-def.c'))
>  stub_ss.add(files('target-monitor-defs.c'))
>