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

[Philippe Mathieu-Daudé]

On 10/18/21 18:14, Alex Bennée wrote:
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>> 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.
> 
> It is? I don't think any of the chardev code touches user-mode, I had to
> add this because apparently other binaries link the libchardev code.

If it isn't then is should call g_assert_not_reached().