[PATCH] radeon: avoid copying over itself ddx fb

[Michel Dänzer]

On Fre, 2012-11-30 at 15:08 -0500, j.glisse at gmail.com wrote: 
> From: Jerome Glisse <jglisse at redhat.com>
> 
> In some rare case it seems that the old fb could already be the
> ddx fb. As copying from the same bo will trigger a ttm deadlck
> detection which will result in infinite kernel/userspace loop.
> Avoid doing any copy as anyway it's useless.
> 
> Signed-off-by: Jerome Glisse <jglisse at redhat.com>
> ---
>  src/drmmode_display.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/src/drmmode_display.c b/src/drmmode_display.c
> index dc608de..15407fe 100644
> --- a/src/drmmode_display.c
> +++ b/src/drmmode_display.c
> @@ -292,6 +292,15 @@ void drmmode_copy_fb(ScrnInfoPtr pScrn, drmmode_ptr drmmode)
>  	if (!fbcon_id)
>  		goto fallback;
>  
> +	if (fbcon_id == drmmode->fb_id) {
> +		/* in some rare case there might be no fbcon and we might already
> +		 * be the one with the current fb to avoid a false deadlck in
> +		 * kernel ttm code just do nothing as anyway there is nothing
> +		 * to do
> +		 */
> +		return;
> +	}

Looks good to me, assuming there's no better way to avoid getting into
this situation in the first place.


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer