[PATCH 2/2] drm/i915: Warn in debug builds of incorrect usages of ptr_pack_bits

Tvrtko Ursulin
2017-10-31T10:23:34Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

GEM_BUG_ON if the packed bits do not fit into the specified width.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_utils.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index af3d7cc53fa1..6a6b497b7dca 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -83,8 +83,10 @@
(typeof(ptr))(__v & -BIT(n)); \
})

-#define ptr_pack_bits(ptr, bits, n) \
- ((typeof(ptr))((unsigned long)(ptr) | (bits)))
+#define ptr_pack_bits(ptr, bits, n) ({ \
+ GEM_BUG_ON((bits) & -BIT(n)); \
+ ((typeof(ptr))((unsigned long)(ptr) | (bits))); \
+})

#define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
#define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
--
2.9.5