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Commit 713648f0 authored by Ørjan Eide's avatar Ørjan Eide Committed by Greg Kroah-Hartman
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staging: sync: Fix race condition between merge and signal 



The copied sync_pt was activated immediately. If the sync_pt was
signaled before the entire merge was completed, the new fence's pt_list
could be iterated over while it is still in the process of being
created.

Moving the the sync_pt_activate call for all new sync_pts to after both
the sync_fence_copy_pts and the sync_fence_merge_pts calls ensure that
the pt_list is complete and immutable before it can be reached from the
timeline's active list.

Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Rob Clark <robclark@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: dri-devel@lists.freedesktop.org
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: default avatarErik Gilling <konkers@android.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b699a644

drivers/staging/android/sync.c

+7 −3
Original line number Diff line number Diff line
@@ -324,7 +324,6 @@ static int sync_fence_copy_pts(struct sync_fence *dst, struct sync_fence *src) 


		new_pt->fence = dst;

		list_add(&new_pt->pt_list, &dst->pt_list_head);

		sync_pt_activate(new_pt);

	}



	return 0;
@@ -357,7 +356,6 @@ static int sync_fence_merge_pts(struct sync_fence *dst, struct sync_fence *src) 
					new_pt->fence = dst;

					list_replace(&dst_pt->pt_list,

						     &new_pt->pt_list);

					sync_pt_activate(new_pt);

					sync_pt_free(dst_pt);

				}

				collapsed = true;
@@ -373,7 +371,6 @@ static int sync_fence_merge_pts(struct sync_fence *dst, struct sync_fence *src) 


			new_pt->fence = dst;

			list_add(&new_pt->pt_list, &dst->pt_list_head);

			sync_pt_activate(new_pt);

		}

	}
@@ -454,6 +451,7 @@ struct sync_fence *sync_fence_merge(const char *name, 
				    struct sync_fence *a, struct sync_fence *b)

{

	struct sync_fence *fence;

	struct list_head *pos;

	int err;



	fence = sync_fence_alloc(name);
@@ -468,6 +466,12 @@ struct sync_fence *sync_fence_merge(const char *name, 
	if (err < 0)

		goto err;



	list_for_each(pos, &fence->pt_list_head) {

		struct sync_pt *pt =

			container_of(pos, struct sync_pt, pt_list);

		sync_pt_activate(pt);

	}



	/*

	 * signal the fence in case one of it's pts were activated before

	 * they were activated