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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: Erik Gilling <konkers@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ørjan Eide 2013-02-28 16:43:24 -08:00 committed by Greg Kroah-Hartman
parent b699a644f8
commit 713648f0f1
1 changed files with 7 additions and 3 deletions
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10
drivers/staging/android/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;
@ -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