Re: [Qemu-devel] [PATCH] Init win32 CRITICAL_SECTION before starting thread; crash when attaching disks

[Stefan Weil <sw@weilnetz.de>]

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Am 29.12.2011 18:29, schrieb Bogdan Harjoc:
> Git commit 8d3bc51 crashes on win32 on startup because 
> qemu_tcg_init_vcpu calls:
>
> qemu_thread_create(th, qemu_tcg_cpu_thread_fn, ...
> ...
> qemu_thread_get_handle(th)
>
> which locks th->data->cs, a CRITICAL_SECTION which is initialized only 
> in the thread_fn, so it finds garbage.
>
> Attached patch initializes it before calling _beginthreadex. 
> GDB/windbg probably start newly created threads sooner, because this 
> doesn't happen under a debugger.
>
> With the patch below it boots until it crashes somewhere while 
> attaching disks (-hda raw_img).
>
> "bt" in gdb only returns "#0  0x00000000 in ??" and generate-core-file 
> didn't work.
>
> Cheers,
>
> diff -du qemu-8d3bc51\qemu-thread-win32.c 
> qemu-8d3bc51-new\qemu-thread-win32.c
> --- qemu-8d3bc51\qemu-thread-win32.c    Tue Dec 27 17:28:58 2011
> +++ qemu-8d3bc51-new\qemu-thread-win32.c    Thu Dec 29 18:59:50 2011
> @@ -215,8 +215,6 @@
>      if (data->mode == QEMU_THREAD_DETACHED) {
>          g_free(data);
>          data = NULL;
> -    } else {
> -        InitializeCriticalSection(&data->cs);
>      }
>      TlsSetValue(qemu_thread_tls_index, data);
>      qemu_thread_exit(start_routine(thread_arg));
> @@ -287,6 +285,10 @@
>      data->arg = arg;
>      data->mode = mode;
>      data->exited = false;
> +
> +    if (data->mode != QEMU_THREAD_DETACHED) {
> +        InitializeCriticalSection(&data->cs);
> +    }
>
>      hThread = (HANDLE) _beginthreadex(NULL, 0, win32_start_routine,
>                                        data, 0, &thread->tid);
>


Tested-by: Stefan Weil <sw@weilnetz.de>


Hi Bogdan,

I can confirm that your patch fixes a crash which otherwise makes
QEMU unusable on Windows hosts.

Could you please sign your patch with a Signed-off-by line including
your name and e-mail address (similar to my Tested-by above)?
We need this before we can commit your patch to QEMU master.

See http://wiki.qemu.org/Contribute/SubmitAPatch for more information.

Please contact me if you need more information.

Regards,

Stefan


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