[Intel-gfx] [PATCH] drm/i915: Fix 32b overflow check in gen8_ppgtt_alloc_page_directories

[Michel Thierry]

The patch 69876bed7e008f5fe01538a2d47c09f2862129d0: "drm/i915/gen8:
page directories rework allocation" added an overflow warning, but the
mask had an extra 0. Use typo-prone option suggested by Dave instead.

This check will be unnecessary after gen8_alloc_va_range handles more
than 4 PDPs (48b addressing).

Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Cc: Dave Gordon <david.s.gordon at intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 6fae6bd..6d894fc 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -756,8 +756,8 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
 
 	WARN_ON(!bitmap_empty(new_pds, GEN8_LEGACY_PDPES));
 
-	/* FIXME: PPGTT container_of won't work for 64b */
-	WARN_ON((start + length) > 0x800000000ULL);
+	/* FIXME: upper bound must not overflow 31 bits  */
+	WARN_ON((start + length) & (~0ULL << 31));
 
 	gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
 		if (pd)
-- 
2.1.1