Re: [Qemu-devel] [PATCH v4 3/4] QemuMutex: support --enable-debug-mutex

["Emilio G. Cota" <cota@braap.org>]

On Mon, Apr 23, 2018 at 13:39:26 +0800, Peter Xu wrote:
> We have had some tracing tools for mutex but it's not easy to use them
> for e.g. dead locks.  Let's provide "--enable-debug-mutex" parameter
> when configure to allow QemuMutex to store the last owner that took
> specific lock.  It will be easy to use this tool to debug deadlocks
> since we can directly know who took the lock then as long as we can have
> a debugger attached to the process.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
(snip)
>  static inline void qemu_mutex_pre_unlock(QemuMutex *mutex,
>                                           const char *file, int line)
>  {
> +#ifdef CONFIG_DEBUG_MUTEX
> +    mutex->file = NULL;
> +    mutex->line = 0;
> +#endif
>      trace_qemu_mutex_unlock(mutex, file, line);
>  }

I'd also initialize to NULL/0 the file/line pair at
qemu_mutex_init time for both posix and win32. Other than that:

Reviewed-by: Emilio G. Cota <cota@braap.org>

Thanks,

		E.