[Intel-gfx] [PATCH] drm/i915/selftests: fix subtraction overflow bug

[Andrzej Hajda]

On some machines hole_end can be small enough to cause subtraction
overflow. On the other side (addr + 2 * min_alignment) can overflow
in case of mock tests. This patch should handle both cases.

Fixes: e1c5f754067b59 ("drm/i915: Avoid overflow in computing pot_hole loop termination")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3674
Signed-off-by: Andrzej Hajda <andrzej.hajda at intel.com>
---
 drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 8633bec18fa75e..ab9f17fc85bcf2 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -742,7 +742,7 @@ static int pot_hole(struct i915_address_space *vm,
 		u64 addr;
 
 		for (addr = round_up(hole_start + min_alignment, step) - min_alignment;
-		     addr <= round_down(hole_end - (2 * min_alignment), step) - min_alignment;
+		     hole_end > addr && hole_end - addr >= 2 * min_alignment;
 		     addr += step) {
 			err = i915_vma_pin(vma, 0, 0, addr | flags);
 			if (err) {
-- 
2.25.1