The ruc and cb_list are never used at the same time. This smal change is actually making the structure 16% smaller.
Signed-off-by: Christian König christian.koenig@amd.com --- 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;
Quoting Christian König (2019-08-07 14:54:05)
The ruc and cb_list are never used at the same time. This smal change is actually making the structure 16% smaller.
(Trivial pair of typos)
Yes. 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 only now makes for a much more spectacular use-after-free. :)
Signed-off-by: Christian König christian.koenig@amd.com
Reviewed-by: Chris Wilson chris@chris-wilson.co.uk -Chris
On Wed, Aug 07, 2019 at 03:01:59PM +0100, Chris Wilson wrote:
Quoting Christian König (2019-08-07 14:54:05)
The ruc and cb_list are never used at the same time. This smal change is actually making the structure 16% smaller.
(Trivial pair of typos)
Yes. 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 only now makes for a much more spectacular use-after-free. :)
^^ stuff the above as an inline kerneldoc comment into the patch? And into the commit message too pls. We need better docs for all this scorcery :-)
Thanks, Daniel
Signed-off-by: Christian König christian.koenig@amd.com
Reviewed-by: Chris Wilson chris@chris-wilson.co.uk -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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