[PATCH 36/45] drm/i915: Add list_for_each_entry_safe_continue_reverse

[Chris Wilson]

One more list iterator variant, for when we want to unwind from inside
one list iterator with the intention of restarting from the current
entry as the new head of the list.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_utils.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index ef8db3aa75c7..3873834f2316 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -266,6 +266,12 @@ static inline int list_is_last_rcu(const struct list_head *list,
 	return READ_ONCE(list->next) == head;
 }
 
+#define list_for_each_entry_safe_continue_reverse(pos, n, head, member)	\
+	for (pos = list_prev_entry(pos, member),			\
+	     n = list_prev_entry(pos, member);				\
+	     &pos->member != (head);					\
+	     pos = n, n = list_prev_entry(n, member))
+
 static inline unsigned long msecs_to_jiffies_timeout(const unsigned int m)
 {
 	unsigned long j = msecs_to_jiffies(m);
-- 
2.20.1