[PATCH 2/3] drm/vkms: stop generating CRCs on buffer overflow

[Daniel Vetter]

On Thu, Jun 13, 2019 at 03:18:01PM +0300, Oleg Vasilev wrote:
> Because interrupts are generated artifitially, kernel bug may lead to
> infinte attempts to submit CRC.
> 
> Signed-off-by: Oleg Vasilev <oleg.vasilev at intel.com>
> ---
>  drivers/gpu/drm/vkms/vkms_crc.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c
> index d7b409a3c0f8..bc717a8888b5 100644
> --- a/drivers/gpu/drm/vkms/vkms_crc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crc.c
> @@ -167,6 +167,7 @@ void vkms_crc_work_handle(struct work_struct *work)
>  	u32 crc32 = 0;
>  	u64 frame_start, frame_end;
>  	unsigned long flags;
> +	int ret;
>  
>  	spin_lock_irqsave(&out->state_lock, flags);
>  	frame_start = crtc_state->frame_start;
> @@ -202,7 +203,14 @@ void vkms_crc_work_handle(struct work_struct *work)
>  	 * missing frames
>  	 */
>  	while (frame_start <= frame_end)
> -		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
> +	{

Bikeshed: Kernel codingstyle puts this on the same line as the closing )
of the while/if/for.

Aside from that not sure that's useful here, we've fixed the bug by now
...
-Daniel

> +		ret = drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
> +		if (ret) {
> +			DRM_WARN("VKMS stop generating CRCs\n");
> +			out->crc_enabled = false;
> +			break;
> +		}
> +	}
>  
>  out:
>  	/* to avoid using the same value for frame number again */
> -- 
> 2.21.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch