[RFC 1/5] dma-buf/fence: add .teardown() ops

[Gustavo Padovan <gustavo@padovan.org>]

From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

fence_array requires a function to clean up its state before we
are able to call fence_put() and release it.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
---
 drivers/dma-buf/fence.c | 7 +++++++
 include/linux/fence.h   | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
index 4d51f9e..4e61afb 100644
--- a/drivers/dma-buf/fence.c
+++ b/drivers/dma-buf/fence.c
@@ -185,6 +185,13 @@ void fence_release(struct kref *kref)
 }
 EXPORT_SYMBOL(fence_release);
 
+void fence_teardown(struct fence *fence)
+{
+	if (fence->ops->teardown)
+		fence->ops->teardown(fence);
+}
+EXPORT_SYMBOL(fence_teardown);
+
 void fence_free(struct fence *fence)
 {
 	kfree_rcu(fence, rcu);
diff --git a/include/linux/fence.h b/include/linux/fence.h
index 44d945e..1d3b671 100644
--- a/include/linux/fence.h
+++ b/include/linux/fence.h
@@ -114,6 +114,7 @@ struct fence_cb {
  * @enable_signaling: enable software signaling of fence.
  * @signaled: [optional] peek whether the fence is signaled, can be null.
  * @wait: custom wait implementation, or fence_default_wait.
+ * @teardown: [optional] teardown fence data but not put it
  * @release: [optional] called on destruction of fence, can be null
  * @fill_driver_data: [optional] callback to fill in free-form debug info
  * Returns amount of bytes filled, or -errno.
@@ -161,6 +162,10 @@ struct fence_cb {
  * which should be treated as if the fence is signaled. For example a hardware
  * lockup could be reported like that.
  *
+ * Notes on teardown:
+ * Can be NULL, this function clean ups the fence data before the fence_put
+ * call.
+ *
  * Notes on release:
  * Can be NULL, this function allows additional commands to run on
  * destruction of the fence. Can be called from irq context.
@@ -173,6 +178,7 @@ struct fence_ops {
 	bool (*enable_signaling)(struct fence *fence);
 	bool (*signaled)(struct fence *fence);
 	signed long (*wait)(struct fence *fence, bool intr, signed long timeout);
+	void (*teardown)(struct fence *fence);
 	void (*release)(struct fence *fence);
 
 	int (*fill_driver_data)(struct fence *fence, void *data, int size);
@@ -184,6 +190,7 @@ void fence_init(struct fence *fence, const struct fence_ops *ops,
 		spinlock_t *lock, u64 context, unsigned seqno);
 
 void fence_release(struct kref *kref);
+void fence_teardown(struct fence *fence);
 void fence_free(struct fence *fence);
 
 /**
-- 
2.5.5