[PATCH xserver 1/2] randr: rrCheckPixmapBounding: Do not substract crtc non 0 x, y from screen size

[Hans de Goede]

Hi,

On 22-11-16 20:41, Dave Airlie wrote:
> On 23 November 2016 at 00:28, Hans de Goede <hdegoede at redhat.com> wrote:
>> The purpose of rrCheckPixmapBounding is to make sure that the
>> screen_pixmap is large enough for the slave-output which crtc is
>> being configured.
>>
>> This should include crtc->x and crtc->y, otherwise the crtc might
>> still end up scanning out an area outside of the screen-pixmap.
>>
>> For example: Take a laptop with an external monitor on a slave-output at
>> 1920x1080+0+0 and its internal-screen at 3840x2160+1920+0 and in
>> gnome-settings-daemon move the external monitor to be on the ri ght of
>> the internal screen rather then on the left. First g-s-d will do a
>> RRSetScreenSize to 5760*2160 (which is a nop), then it calls RRSetCrtc
>> to move the slave output to 1920x1080+3840+0, since this is a slave
>> output, rrCheckPixmapBounding gets called, since the 2 crtcs now overlap
>> the code before this commit would shrinks the screen_pixmap to 3180*2160.
>> Then g-s-d calls RRSetCrtc to move the internal screen to 3180*2160+0+0.
>>
>> And we end up with the slave-output configured to scan-out an area
>> which completely falls outside of the screen-pixmap (and end up with
>> a black display on the external monitor).
>>
>> This commit fixes this by not substracting the x1 and y1 coordinates
>> of the union-ed region when determining the new screen_pixmap size.
>>
>> Cc: Nikhil Mahale <nmahale at nvidia.com>
>> Cc: Dave Airlie <airlied at redhat.com>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>
> Thanks Hans, these seems to make sense to me.
>
> Reviewed-by: Dave Airlie <airlied at redhat.com>

Thank you, "these" means the reviewed-by is for the series, right ?

Ajax, Keith, the exact push policy for the server is a bit unclear to
me now, I've seen several people push their own patches after a favorable
review. So can I just push these 2 with Dave's reviewed-by, or ... ?

Regards,

Hans




>
>> ---
>>  randr/rrcrtc.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/randr/rrcrtc.c b/randr/rrcrtc.c
>> index 5d404e8..ac853ea 100644
>> --- a/randr/rrcrtc.c
>> +++ b/randr/rrcrtc.c
>> @@ -686,8 +686,8 @@ rrCheckPixmapBounding(ScreenPtr pScreen,
>>      }
>>
>>      newsize = RegionExtents(&total_region);
>> -    new_width = newsize->x2 - newsize->x1;
>> -    new_height = newsize->y2 - newsize->y1;
>> +    new_width = newsize->x2;
>> +    new_height = newsize->y2;
>>
>>      if (new_width == screen_pixmap->drawable.width &&
>>          new_height == screen_pixmap->drawable.height) {
>> --
>> 2.9.3
>>
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