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

[Stefan Weil]

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 = ""> -    } 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 <address@hidden>


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