This is a note to let you know that I've just added the patch titled
dma-buf: make reservation_object_copy_fences rcu save
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: dma-buf-make-reservation_object_copy_fences-rcu-save.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 39e16ba16c147e662bf9fbcee9a99d70d420382f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= christian.koenig@amd.com Date: Mon, 4 Sep 2017 21:02:45 +0200 Subject: dma-buf: make reservation_object_copy_fences rcu save MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
From: Christian König christian.koenig@amd.com
commit 39e16ba16c147e662bf9fbcee9a99d70d420382f upstream.
Stop requiring that the src reservation object is locked for this operation.
Acked-by: Chunming Zhou david1.zhou@amd.com Signed-off-by: Christian König christian.koenig@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Link: https://patchwork.freedesktop.org/patch/msgid/1504551766-5093-1-git-send-ema... Signed-off-by: Lyude Paul lyude@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/dma-buf/reservation.c | 56 +++++++++++++++++++++++++++++++----------- 1 file changed, 42 insertions(+), 14 deletions(-)
--- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -266,8 +266,7 @@ EXPORT_SYMBOL(reservation_object_add_exc * @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(struc 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);
Patches currently in stable-queue which might be from christian.koenig@amd.com are
queue-4.14/drm-ttm-fix-ttm_bo_cleanup_refs_or_queue-once-more.patch queue-4.14/drm-amdgpu-potential-uninitialized-variable-in-amdgpu_vce_ring_parse_cs.patch queue-4.14/drm-amdgpu-properly-allocate-vm-invalidate-eng-v2.patch queue-4.14/drm-amdgpu-potential-uninitialized-variable-in-amdgpu_vm_update_directories.patch queue-4.14/drm-amdgpu-fix-error-handling-in-amdgpu_bo_do_create.patch queue-4.14/dma-buf-make-reservation_object_copy_fences-rcu-save.patch