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sync: Fix race condition between merge and signal

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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.

Signed-off-by: Erik Gilling <konkers@android.com>
This commit is contained in:
Ørjan Eide
2012-12-05 16:38:08 +01:00
committed by 黄涛
parent ae739c14a7
commit df5c61bad0
1 changed files with 7 additions and 3 deletions
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10
drivers/base/sync.c
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@@ -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;
@@ -356,7 +355,6 @@ 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;
@@ -372,7 +370,6 @@ 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);
}
}
@@ -453,6 +450,7 @@ 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);
@@ -467,6 +465,12 @@ 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