[PATCH v2 03/17] locking/lockdep: Add helper functions to operate on the searched path

Yuyang Du
2019-05-16T08:00:38Z

- find_lock_in_path() tries to find whether a lock class is in the path.

- find_next_dep_in_path() returns the next dependency after a
given dependency in the path.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
kernel/locking/lockdep.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e7eedbf..595dc94 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1365,6 +1365,37 @@ static inline int get_lock_depth(struct lock_list *child)
}

/*
+ * Return the dependency if @lock is in the path, otherwise NULL.
+ */
+static inline struct lock_list *
+find_lock_in_path(struct lock_class *lock, struct lock_list *target)
+{
+ while ((target = get_lock_parent(target)))
+ if (target->class == lock)
+ return target;
+
+ return NULL;
+}
+
+/*
+ * Walk back to the next dependency after @source from @target. Note
+ * that @source must be in the path, and @source can not be the same as
+ * @target, otherwise this is going to fail and reutrn NULL.
+ */
+static inline struct lock_list *
+find_next_dep_in_path(struct lock_list *source, struct lock_list *target)
+{
+ while (get_lock_parent(target) != source) {
+ target = get_lock_parent(target);
+
+ if (!target)
+ break;
+ }
+
+ return target;
+}
+
+/*
* Return the forward or backward dependency list.
*
* @lock: the lock_list to get its class's dependency list
--
1.8.3.1