[PATCH] dma-buf: make dma_fence structure a bit smaller

From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org
Subject: [PATCH] dma-buf: make dma_fence structure a bit smaller
Date: Thu,  8 Aug 2019 15:14:45 +0200	[thread overview]
Message-ID: <20190808131445.23372-1-christian.koenig@amd.com> (raw)

We clear the callback list on kref_put so that by the time we
release the fence it is unused. No one should be adding to the cb_list
that they don't themselves hold a reference for.

This small change is actually making the structure 16% smaller.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 include/linux/dma-fence.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 05d29dbc7e62..3985c72cd0c2 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -65,8 +65,10 @@ struct dma_fence_cb;
 struct dma_fence {
 	struct kref refcount;
 	const struct dma_fence_ops *ops;
-	struct rcu_head rcu;
-	struct list_head cb_list;
+	union {
+		struct rcu_head rcu;
+		struct list_head cb_list;
+	};
 	spinlock_t *lock;
 	u64 context;
 	u64 seqno;
-- 
2.17.1

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