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

[Alex Bennée]

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.

> 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'))
>> 


-- 
Alex Bennée