Re: [PATCH] drm/i915: do not return invalid pointers as a *dentry

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Thu, Jan 31, 2019 at 02:15:07PM +0100, Greg Kroah-Hartman wrote:
> When calling debugfs functions, they can now return error values if
> something went wrong.  If that happens, return a NULL as a *dentry to
> the relay core instead of passing it an illegal pointer.
> 
> The relay core should be able to handle an illegal pointer, but add this
> check to be safe.
> 
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: intel-gfx@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/gpu/drm/i915/intel_guc_log.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
> index d3ebdbc0182e..8bf03497dcd8 100644
> --- a/drivers/gpu/drm/i915/intel_guc_log.c
> +++ b/drivers/gpu/drm/i915/intel_guc_log.c
> @@ -140,6 +140,9 @@ static struct dentry *create_buf_file_callback(const char *filename,
>  
>  	buf_file = debugfs_create_file(filename, mode,
>  				       parent, buf, &relay_file_operations);
> +	if (IS_ERR(buf_file))
> +		return NULL;

I still see a return NULL inside debugfs_create_file on master,
but probably you are ahead with some change that I didn't see yet right?

I'm just wondering if it wouldn't be better for now to go with

if (IS_ERR_OR_NULL(buf_file))

apparently we also need it on i915_debugfs.c i915_debugfs_register()

Thanks,
Rodrigo.

> +
>  	return buf_file;
>  }
>  
> -- 
> 2.20.1
> 
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