linux-kernel - Re: [PATCH] drm/vmwgfx: remove DRM_ERROR message, stops log spamming

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Date:   Tue, 12 Sep 2017 19:42:02 +0200
From:   Thomas Hellstrom <thellstrom@...are.com>
To:     Colin King <colin.king@...onical.com>,
        VMware Graphics <linux-graphics-maintainer@...are.com>,
        Sinclair Yeh <syeh@...are.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/vmwgfx: remove DRM_ERROR message, stops log spamming

Hi, Colin,

On 09/12/2017 07:35 PM, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
>
> mmap'ing the device multiple times will spam the kernel log with the
> DRM_ERROR message about illegal mmap'ing the old fifo space.
How are you hitting this? Multiple mappings should be fine as long as 
mapping offsets are correct,
so hitting this message should indicate that the user-space app is doing 
something seriously wrong, and
having it present in the log should probably help more than it hurts.

/Thomas



> Since
> the mmap'ing will fail with an -EINVAL there is no need to emit this
> message, so just remove it.
>
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>   drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> index e771091d2cd3..1e633c602fb1 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> @@ -33,10 +33,8 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
>   	struct drm_file *file_priv;
>   	struct vmw_private *dev_priv;
>   
> -	if (unlikely(vma->vm_pgoff < VMWGFX_FILE_PAGE_OFFSET)) {
> -		DRM_ERROR("Illegal attempt to mmap old fifo space.\n");
> +	if (unlikely(vma->vm_pgoff < VMWGFX_FILE_PAGE_OFFSET))
>   		return -EINVAL;
> -	}
>   
>   	file_priv = filp->private_data;
>   	dev_priv = vmw_priv(file_priv->minor->dev);