drm/i915: Assert that the exec object lookup table is a power-of-two

As we make the simplification of using a power-of-two size for the
execbuffer handle-to-object TLB, we should validate that this is actually
true and so clarify that premise.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 8186f63..6a2f3e5 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -44,6 +44,7 @@ eb_create(int size)
 {
        struct eb_objects *eb;
        int count = PAGE_SIZE / sizeof(struct hlist_head) / 2;
+       BUILD_BUG_ON(!is_power_of_2(PAGE_SIZE / sizeof(struct hlist_head)));
        while (count > size)
                count >>= 1;
        eb = kzalloc(count*sizeof(struct hlist_head) +