[PATCH] drm: idr_find (drm_gem_object_lookup) needs only rcu read locks

[Chris Wilson]

On Thu,  4 Nov 2010 10:09:53 +0000, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>  	/* Release reference and decrement refcount. */
>  	idr_remove(&filp->object_idr, handle);
>  	spin_unlock(&filp->table_lock);
>  
> +	synchronize_rcu();
> +

This is an absolute performance killer. Looks like we might have to endure
call_rcu if we want to proceed down this path.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre