[REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[Peter Rosin]

Blitting an image with "negative" offsets is not working since there
is no clipping. It hopefully just crashes. For the bootup logo, there
is protection so that blitting does not happen as the image is drawn
further and further to the right (ROTATE_UR) or further and further
down (ROTATE_CW). There is however no protection when drawing in the
opposite directions (ROTATE_UD and ROTATE_CCW).

Add back this protection.

The regression is 20-odd years old but the mindless warning-killing
mentality displayed in commit 34bdb666f4b2 ("fbdev: fbmem: remove
positive test on unsigned values") is also to blame, methinks.

Fixes: 448d479747b8 ("fbdev: fb_do_show_logo() updates")
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/video/fbdev/core/fbmem.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index bb7f5f23e347..1abeb0b72455 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -435,7 +435,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
 			image->dx += image->width + 8;
 		}
 	} else if (rotate == FB_ROTATE_UD) {
-		for (x = 0; x < num; x++) {
+		u32 dx = image->dx;
+
+		for (x = 0; x < num && image->dx <= dx; x++) {
 			info->fbops->fb_imageblit(info, image);
 			image->dx -= image->width + 8;
 		}
@@ -447,7 +449,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
 			image->dy += image->height + 8;
 		}
 	} else if (rotate == FB_ROTATE_CCW) {
-		for (x = 0; x < num; x++) {
+		u32 dy = image->dy;
+
+		for (x = 0; x < num && image->dy <= dy; x++) {
 			info->fbops->fb_imageblit(info, image);
 			image->dy -= image->height + 8;
 		}
-- 
2.11.0

Re: [REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[Peter Rosin]

Ping?!

Cheers,
Peter

On 2018-11-08 10:54, Peter Rosin wrote:
> Blitting an image with "negative" offsets is not working since there
> is no clipping. It hopefully just crashes. For the bootup logo, there
> is protection so that blitting does not happen as the image is drawn
> further and further to the right (ROTATE_UR) or further and further
> down (ROTATE_CW). There is however no protection when drawing in the
> opposite directions (ROTATE_UD and ROTATE_CCW).
> 
> Add back this protection.
> 
> The regression is 20-odd years old but the mindless warning-killing
> mentality displayed in commit 34bdb666f4b2 ("fbdev: fbmem: remove
> positive test on unsigned values") is also to blame, methinks.
> 
> Fixes: 448d479747b8 ("fbdev: fb_do_show_logo() updates")
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
>  drivers/video/fbdev/core/fbmem.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index bb7f5f23e347..1abeb0b72455 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -435,7 +435,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
>  			image->dx += image->width + 8;
>  		}
>  	} else if (rotate == FB_ROTATE_UD) {
> -		for (x = 0; x < num; x++) {
> +		u32 dx = image->dx;
> +
> +		for (x = 0; x < num && image->dx <= dx; x++) {
>  			info->fbops->fb_imageblit(info, image);
>  			image->dx -= image->width + 8;
>  		}
> @@ -447,7 +449,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
>  			image->dy += image->height + 8;
>  		}
>  	} else if (rotate == FB_ROTATE_CCW) {
> -		for (x = 0; x < num; x++) {
> +		u32 dy = image->dy;
> +
> +		for (x = 0; x < num && image->dy <= dy; x++) {
>  			info->fbops->fb_imageblit(info, image);
>  			image->dy -= image->height + 8;
>  		}
> 

Re: [REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[Bartlomiej Zolnierkiewicz]

On 11/26/2018 03:16 PM, Peter Rosin wrote:
> Ping?!

Hi,

Thank you for your patch, it will be considered for 4.21 (as it is not
a recent regression + I'm busy with other things currently).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> Cheers,
> Peter
> 
> On 2018-11-08 10:54, Peter Rosin wrote:
>> Blitting an image with "negative" offsets is not working since there
>> is no clipping. It hopefully just crashes. For the bootup logo, there
>> is protection so that blitting does not happen as the image is drawn
>> further and further to the right (ROTATE_UR) or further and further
>> down (ROTATE_CW). There is however no protection when drawing in the
>> opposite directions (ROTATE_UD and ROTATE_CCW).
>>
>> Add back this protection.
>>
>> The regression is 20-odd years old but the mindless warning-killing
>> mentality displayed in commit 34bdb666f4b2 ("fbdev: fbmem: remove
>> positive test on unsigned values") is also to blame, methinks.
>>
>> Fixes: 448d479747b8 ("fbdev: fb_do_show_logo() updates")
>> Signed-off-by: Peter Rosin <peda@axentia.se>
>> ---
>>  drivers/video/fbdev/core/fbmem.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
>> index bb7f5f23e347..1abeb0b72455 100644
>> --- a/drivers/video/fbdev/core/fbmem.c
>> +++ b/drivers/video/fbdev/core/fbmem.c
>> @@ -435,7 +435,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
>>  			image->dx += image->width + 8;
>>  		}
>>  	} else if (rotate == FB_ROTATE_UD) {
>> -		for (x = 0; x < num; x++) {
>> +		u32 dx = image->dx;
>> +
>> +		for (x = 0; x < num && image->dx <= dx; x++) {
>>  			info->fbops->fb_imageblit(info, image);
>>  			image->dx -= image->width + 8;
>>  		}
>> @@ -447,7 +449,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
>>  			image->dy += image->height + 8;
>>  		}
>>  	} else if (rotate == FB_ROTATE_CCW) {
>> -		for (x = 0; x < num; x++) {
>> +		u32 dy = image->dy;
>> +
>> +		for (x = 0; x < num && image->dy <= dy; x++) {
>>  			info->fbops->fb_imageblit(info, image);
>>  			image->dy -= image->height + 8;
>>  		}

Re: [REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[Peter Rosin]

On 2018-11-26 15:33, Bartlomiej Zolnierkiewicz wrote:
> On 11/26/2018 03:16 PM, Peter Rosin wrote:
>> Ping?!
> 
> Hi,
> 
> Thank you for your patch, it will be considered for 4.21 (as it is not
> a recent regression + I'm busy with other things currently).

Right, thanks for letting me know!

Cheers,
Peter

Re: [REGRESSION PATCH] fbdev: fbmem: behave better with small rotated displays and many CPUs

[Bartlomiej Zolnierkiewicz]

On 11/26/2018 10:19 PM, Peter Rosin wrote:
> On 2018-11-26 15:33, Bartlomiej Zolnierkiewicz wrote:
>> On 11/26/2018 03:16 PM, Peter Rosin wrote:
>>> Ping?!
>>
>> Hi,
>>
>> Thank you for your patch, it will be considered for 4.21 (as it is not
>> a recent regression + I'm busy with other things currently).
> 
> Right, thanks for letting me know!

Patch queued for 4.21, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics