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;a=summary
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@xxxxxxxxxxxxxxx> know about it.
>From 39e16ba16c147e662bf9fbcee9a99d70d420382f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@xxxxxxx>
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
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From: Christian König <christian.koenig@xxxxxxx>
commit 39e16ba16c147e662bf9fbcee9a99d70d420382f upstream.
Stop requiring that the src reservation object is locked for this operation.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxx 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