Ping? David can you take a look?
Alex is on vacation and that is a rather important bug fix.
Thanks,
Christian.
Am 04.09.2017 um 21:02 schrieb Christian König:
> From: Christian König <christian.koenig at amd.com>
>
> Stop requiring that the src reservation object is locked for this operation.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
> drivers/dma-buf/reservation.c | 56 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 42 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
> index dec3a81..b44d9d7 100644
> --- a/drivers/dma-buf/reservation.c
> +++ b/drivers/dma-buf/reservation.c
> @@ -266,8 +266,7 @@ EXPORT_SYMBOL(reservation_object_add_excl_fence);
> * @dst: the destination reservation object
> * @src: the source reservation object
> *
> -* Copy all fences from src to dst. Both src->lock as well as dst-lock must be
> -* held.
> +* Copy all fences from src to dst. dst-lock must be held.
> */
> int reservation_object_copy_fences(struct reservation_object *dst,
> struct reservation_object *src)
> @@ -277,33 +276,62 @@ int reservation_object_copy_fences(struct reservation_object *dst,
> size_t size;
> unsigned i;
>
> - src_list = reservation_object_get_list(src);
> + rcu_read_lock();
> + src_list = rcu_dereference(src->fence);
>
> +retry:
> if (src_list) {
> - size = offsetof(typeof(*src_list),
> - shared[src_list->shared_count]);
> + unsigned shared_count = src_list->shared_count;
> +
> + size = offsetof(typeof(*src_list), shared[shared_count]);
> + rcu_read_unlock();
> +
> dst_list = kmalloc(size, GFP_KERNEL);
> if (!dst_list)
> return -ENOMEM;
>
> - dst_list->shared_count = src_list->shared_count;
> - dst_list->shared_max = src_list->shared_count;
> - for (i = 0; i < src_list->shared_count; ++i)
> - dst_list->shared[i] =
> - dma_fence_get(src_list->shared[i]);
> + rcu_read_lock();
> + src_list = rcu_dereference(src->fence);
> + if (!src_list || src_list->shared_count > shared_count) {
> + kfree(dst_list);
> + goto retry;
> + }
> +
> + dst_list->shared_count = 0;
> + dst_list->shared_max = shared_count;
> + for (i = 0; i < src_list->shared_count; ++i) {
> + struct dma_fence *fence;
> +
> + fence = rcu_dereference(src_list->shared[i]);
> + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> + &fence->flags))
> + continue;
> +
> + if (!dma_fence_get_rcu(fence)) {
> + kfree(dst_list);
> + src_list = rcu_dereference(src->fence);
> + goto retry;
> + }
> +
> + if (dma_fence_is_signaled(fence)) {
> + dma_fence_put(fence);
> + continue;
> + }
> +
> + dst_list->shared[dst_list->shared_count++] = fence;
> + }
> } else {
> dst_list = NULL;
> }
>
> + new = dma_fence_get_rcu_safe(&src->fence_excl);
> + rcu_read_unlock();
> +
> kfree(dst->staged);
> dst->staged = NULL;
>
> src_list = reservation_object_get_list(dst);
> -
> old = reservation_object_get_excl(dst);
> - new = reservation_object_get_excl(src);
> -
> - dma_fence_get(new);
>
> preempt_disable();
> write_seqcount_begin(&dst->seq);
