[PATCH v6 1/7] winex11.drv: Add Xinerama display device handler.

[Huw Davies]

On Wed, May 22, 2019 at 05:16:32PM +0800, Zhiyi Zhang wrote:
> Display device handlers are used to initialize the display device
> registry data. Different handlers can be implemented according to
> the defined interface, for example, via Xinerama or XRandR.
> With those registry data, EnumDisplayDevices, EnumDisplayMonitors
> and GetMonitorInfo can be built on top of it.
> 
> Signed-off-by: Zhiyi Zhang <zzhang at codeweavers.com>
> ---
> v2: Supersede 162308~162314, fix xinerama primary adapter reporting, fix registry data reinit failure.
> v3: Rebase
> v4: Merge patches. Rebase. Supersede 164594~164599, 164612~164613
> v5: Fix explorer patch triggered user32 test failures. Supersede 165122~165128.
> v6: Restructure patches. Supersede 165134~165140

Thanks, this order makes it easier to see what you're adding.

> +void X11DRV_DisplayDevices_Init(void)
> +{
> +    HKEY video_hkey = NULL;
> +    DWORD disposition = 0;
> +    BOOL success = FALSE;
> +
> +    TRACE("via %s\n", wine_dbgstr_a(handler.name));
> +
> +    if (RegCreateKeyExW(HKEY_LOCAL_MACHINE, video_keyW, 0, NULL, REG_OPTION_VOLATILE, KEY_ALL_ACCESS, NULL, &video_hkey,
> +                        &disposition))
> +        goto fail;
> +
> +    /* Ensure only one thread is initializing the registry and avoid unnecessary reinit */
> +    if (disposition != REG_CREATED_NEW_KEY)
> +    {
> +        success = TRUE;
> +        goto fail;
> +    }
> +
> +    success = TRUE;
> +fail:
> +    RegCloseKey(video_hkey);
> +    if (!success)
> +        ERR("Failed to initialize display devices\n");
> +}

So, the second thread (or process) will just carry on.  That's
going to leave it racing with the first if it tries to read the
registry data.

Huw.