On Fri, Aug 09, 2013 at 10:12:15PM -0700, Ben Widawsky wrote:
The conditional is usually a recoverable driver bug, and so WARNing, and preventing the drm_mm code from doing potential damage (BUG) is desirable.
This issue was hit and fixed twice while developing the i915 multiple address space code. The first fix is the patch just before this, and is hit on an not frequently occuring error path. Another was fixed during patch iteration, so it's hard to see from the patch:
commit c6cfb325677ea6305fb19acf3a4d14ea267f923e Author: Ben Widawsky ben@bwidawsk.net Date: Fri Jul 5 14:41:06 2013 -0700
drm/i915: Embed drm_mm_node in i915 gem objFrom the intel-gfx mailing list, we discussed this: References: 20130705191235.GA3057@bwidawsk.net
Cc: Dave Airlie airlied@redhat.com CC: dri-devel@lists.freedesktop.org Signed-off-by: Ben Widawsky ben@bwidawsk.net
On the other hand, if we end up with a proliferation of if (drm_mm_node_allocated(node)) drm_mm_remove_node(node) in the drivers, putting the guard into remove_node is preferrable. At the moment we only have the one error path in i915.ko where we need to double check so it is not much of a concern.
Acked-by: Chris Wilson chris@chris-wilson.co.uk -Chris