Re: [PATCH 1/3] drm: Balance error path for GEM handle allocation

Ville Syrjälä
2016-01-04T15:24:11Z

On Mon, Jan 04, 2016 at 10:10:59AM +0000, Chris Wilson wrote:
> The current error path for failure when establishing a handle for a GEM
> object is unbalance, e.g. we call object_close() without calling first
> object_open(). Use the typical onion structure to only undo what has
> been set up prior to the error.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/drm_gem.c | 29 +++++++++++++++++------------
> 1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 2e10bba4468b..a08176debc0e 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -343,27 +343,32 @@ drm_gem_handle_create_tail(struct drm_file *file_priv,
> spin_unlock(&file_priv->table_lock);
> idr_preload_end();
> mutex_unlock(&dev->object_name_lock);
> - if (ret < 0) {
> - drm_gem_object_handle_unreference_unlocked(obj);
> - return ret;
> - }
> + if (ret < 0)
> + goto err_unref;
> +
> *handlep = ret;
>
> ret = drm_vma_node_allow(&obj->vma_node, file_priv->filp);
> - if (ret) {
> - drm_gem_handle_delete(file_priv, *handlep);
> - return ret;
> - }
> + if (ret)
> + goto err_remove;
>
> if (dev->driver->gem_open_object) {
> ret = dev->driver->gem_open_object(obj, file_priv);
> - if (ret) {
> - drm_gem_handle_delete(file_priv, *handlep);
> - return ret;
> - }
> + if (ret)
> + goto err_revoke;
> }
>
> return 0;
> +
> +err_revoke:
> + drm_vma_node_revoke(&obj->vma_node, file_priv->filp);
> +err_remove:
> + spin_lock(&file_priv->table_lock);
> + idr_remove(&file_priv->object_idr, *handlep);
> + spin_unlock(&file_priv->table_lock);
> +err_unref:
> + drm_gem_object_handle_unreference_unlocked(obj);
> + return ret;

First I misread this as drm_gem_object_unreference_unlocked()
and though we'd leak the handle_count++, but it's
drm_gem_object_handle_unreference_unlocked() which does the
handle_count-- we need.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> }
>
> /**
> --
> 2.6.4
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Ville Syrjälä
Intel OTC