From: Christian König <christian.koenig@xxxxxxx> Stop requiring that the src reservation object is locked for this operation. commit 39e16ba16c147e662bf9fbcee9a99d70d420382f upstream Acked-by: Chunming Zhou <david1.zhou@xxxxxxx> Signed-off-by: Christian König <christian.koenig@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/1504551766-5093-1-git-send-email-deathsimple@xxxxxxxxxxx Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx> --- 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 dec3a815455d..b44d9d7db347 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); -- 2.14.3