[Intel-gfx] [PATCH 02/26] dma-buf: add dma_resv_for_each_fence

Christian König
2021-09-22T12:45:24Z

A simpler version of the iterator to be used when the dma_resv object is
locked.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/dma-buf/dma-resv.c | 46 ++++++++++++++++++++++++++++++++++++++
include/linux/dma-resv.h | 19 ++++++++++++++++
2 files changed, 65 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 7768140ab36d..c6f1f6837b55 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -418,6 +418,52 @@ struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
}
EXPORT_SYMBOL(dma_resv_iter_next_unlocked);

+/**
+ * dma_resv_iter_first - first fence from a locked dma_resv object
+ * @cursor: cursor to record the current position
+ *
+ * Return all the fences in the dma_resv object while holding the
+ * &dma_resv.lock.
+ */
+struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
+{
+ struct dma_fence *fence;
+
+ dma_resv_assert_held(cursor->obj);
+
+ cursor->index = -1;
+ cursor->fences = dma_resv_shared_list(cursor->obj);
+
+ fence = dma_resv_excl_fence(cursor->obj);
+ if (!fence)
+ fence = dma_resv_iter_next(cursor);
+
+ cursor->is_restarted = true;
+ return fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_first);
+
+/**
+ * dma_resv_iter_next - next fence from a locked dma_resv object
+ * @cursor: cursor to record the current position
+ *
+ * Return all the fences in the dma_resv object while holding the
+ * &dma_resv.lock.
+ */
+struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
+{
+ dma_resv_assert_held(cursor->obj);
+
+ cursor->is_restarted = false;
+ if (!cursor->all_fences || !cursor->fences ||
+ ++cursor->index >= cursor->fences->shared_count)
+ return NULL;
+
+ return rcu_dereference_protected(cursor->fences->shared[cursor->index],
+ dma_resv_held(cursor->obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_next);
+
/**
* dma_resv_copy_fences - Copy all fences from src to dst.
* @dst: the destination reservation object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index baf77a542392..72e7ebaa675f 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -179,6 +179,8 @@ struct dma_resv_iter {

struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
+struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor);
+struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor);

/**
* dma_resv_iter_begin - initialize a dma_resv_iter object
@@ -244,6 +246,23 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
for (fence = dma_resv_iter_first_unlocked(cursor); \
fence; fence = dma_resv_iter_next_unlocked(cursor))

+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @cursor: a struct dma_resv_iter pointer
+ * @obj: a dma_resv object pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object while holding the
+ * &dma_resv.lock. @all_fences controls if the shared fences are returned as
+ * well. The cursor initialisation is part of the iterator and the fence stays
+ * valid as long as the lock is held.
+ */
+#define dma_resv_for_each_fence(cursor, obj, all_fences, fence) \
+ for (dma_resv_iter_begin(cursor, obj, all_fences), \
+ fence = dma_resv_iter_first(cursor); fence; \
+ fence = dma_resv_iter_next(cursor))
+
#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)

--
2.25.1