[2/3] drm/mst: Fix error handling during MST sideband message reception

[Lyude Paul]

On Thu, 2016-05-12 at 16:00 +0300, Imre Deak wrote:
> Handle any error due to partial reads, timeouts etc. to avoid parsing
> uninitialized data subsequently. Also bail out if the parsing itself
> fails.
> 
> CC: Dave Airlie <airlied at redhat.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index a13edf5..12c0ab3 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2204,11 +2204,19 @@ static void drm_dp_get_one_sb_msg(struct
> drm_dp_mst_topology_mgr *mgr, bool up)
>              ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
>                                  replyblock, len);
>              if (ret != len) {
> -                     DRM_DEBUG_KMS("failed to read a chunk\n");
> +                     DRM_DEBUG_KMS("failed to read a chunk (len %d, ret
> %d)\n",
> +                                   len, ret);
> +
I'd get rid of the whitespace here…
> +                     return;
>              }
> +
>              ret = drm_dp_sideband_msg_build(msg, replyblock, len, false);
> -             if (ret == false)
> +             if (!ret) {
>                      DRM_DEBUG_KMS("failed to build sideband msg\n");
> +
And here, to match the rest of the file. Otherwise looks good to me;

Reviewed-by: Lyude <cpaul at redhat.com>
> +                     return;
> +             }
> +
>              curreply += len;
>              replylen -= len;
>      }