From: Chris Wilson chris@chris-wilson.co.uk
Wrap cmpxchg64 with a try_cmpxchg()-esque helper. Hiding the old-value dance in the helper allows for cleaner code.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@intel.com --- drivers/gpu/drm/i915/i915_utils.h | 32 +++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index c3d234133da7..a42d9ddd0415 100644 --- a/drivers/gpu/drm/i915/i915_utils.h +++ b/drivers/gpu/drm/i915/i915_utils.h @@ -475,4 +475,36 @@ void __mark_lock_used_irq(struct lockdep_map *lock); */ #define IS_ACTIVE(config) ((config) != 0)
+#ifndef try_cmpxchg64 +#if IS_ENABLED(CONFIG_64BIT) +#define try_cmpxchg64(_ptr, _pold, _new) try_cmpxchg(_ptr, _pold, _new) +#else +#define try_cmpxchg64(_ptr, _pold, _new) \ +({ \ + __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \ + __typeof__(*(_ptr)) __old = *_old; \ + __typeof__(*(_ptr)) __cur = cmpxchg64(_ptr, __old, _new); \ + bool success = __cur == __old; \ + if (unlikely(!success)) \ + *_old = __cur; \ + likely(success); \ +}) +#endif +#endif + +#ifndef xchg64 +#if IS_ENABLED(CONFIG_64BIT) +#define xchg64(_ptr, _new) xchg(_ptr, _new) +#else +#define xchg64(_ptr, _new) \ +({ \ + __typeof__(_ptr) __ptr = (_ptr); \ + __typeof__(*(_ptr)) __old = *__ptr; \ + while (!try_cmpxchg64(__ptr, &__old, (_new))) \ + ; \ + __old; \ +}) +#endif +#endif + #endif /* !__I915_UTILS_H */