Commit 5e963508 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Use cmpxchg64 for 32b compatilibity 



By using the double wide cmpxchg64 on 32bit, we can use the same
algorithm on both 32/64b systems.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201211110310.22740-1-chris@chris-wilson.co.uk
parent d484bd0d

drivers/gpu/drm/i915/i915_active.c

+2 −5
Original line number Diff line number Diff line
@@ -159,7 +159,6 @@ __active_retire(struct i915_active *ref) 
		GEM_BUG_ON(ref->tree.rb_node != &ref->cache->node);



		/* Make the cached node available for reuse with any timeline */

		if (IS_ENABLED(CONFIG_64BIT))

		ref->cache->timeline = 0; /* needs cmpxchg(u64) */

	}
@@ -256,7 +255,6 @@ static struct active_node *__active_lookup(struct i915_active *ref, u64 idx) 
		if (cached == idx)

			return it;



#ifdef CONFIG_64BIT /* for cmpxchg(u64) */

		/*

		 * An unclaimed cache [.timeline=0] can only be claimed once.

		 *
@@ -267,9 +265,8 @@ static struct active_node *__active_lookup(struct i915_active *ref, u64 idx) 
		 * only the winner of that race will cmpxchg return the old

		 * value of 0).

		 */

		if (!cached && !cmpxchg(&it->timeline, 0, idx))

		if (!cached && !cmpxchg64(&it->timeline, 0, idx))

			return it;

#endif

	}



	BUILD_BUG_ON(offsetof(typeof(*it), node));