drm/i915: introduce range_overflows utility macros

In a number places we hand-roll the overflow sanity check for ranges, so
roll that into single macro, conceived by Chris, along with its typed
variant.

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161213203222.32564-3-matthew.auld@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 20bc04d5e6175927b885f768299dd8a266065fce..085c8ecd09b54c48208251f1b29089626e6e9094 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -218,6 +218,18 @@ static inline const char *enableddisabled(bool v)
        return v ? "enabled" : "disabled";
 }
 
+#define range_overflows(start, size, max) ({ \
+       typeof(start) start__ = (start); \
+       typeof(size) size__ = (size); \
+       typeof(max) max__ = (max); \
+       (void)(&start__ == &size__); \
+       (void)(&start__ == &max__); \
+       start__ > max__ || size__ > max__ - start__; \
+})
+
+#define range_overflows_t(type, start, size, max) \
+       range_overflows((type)(start), (type)(size), (type)(max))
+
 enum pipe {
        INVALID_PIPE = -1,
        PIPE_A = 0,