linux-kernel - [PATCH v2 17/19] locking/lockdep: Combine check_noncircular and check

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Date:   Mon, 18 Mar 2019 16:57:31 +0800
From:   Yuyang Du <duyuyang@...il.com>
To:     peterz@...radead.org, will.deacon@....com, mingo@...nel.org
Cc:     bvanassche@....org, ming.lei@...hat.com,
        linux-kernel@...r.kernel.org, Yuyang Du <duyuyang@...il.com>
Subject: [PATCH v2 17/19] locking/lockdep: Combine check_noncircular and check_redundant

These two functions are essentially duplicates, combine them.

No functional change.

Signed-off-by: Yuyang Du <duyuyang@...il.com>
---
 kernel/locking/lockdep.c | 29 ++++++++++-------------------
 1 file changed, 10 insertions(+), 19 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 3dbb4d0..90d58cc 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1677,29 +1677,18 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
 }
 
 /*
- * Prove that the dependency graph starting at <entry> can not
- * lead to <target>. Print an error and return 0 if it does.
+ * Prove that the dependency graph starting at <root> can not
+ * lead to <target>. If existent, there is a circle when adding
+ * a <target> -> <root> dependency.
+ *
+ * Print an error and return 0 if it does exist.
  */
 static noinline int
-check_noncircular(struct lock_list *root, struct lock_class *target,
+check_nonexistent(struct lock_list *root, struct lock_class *target,
 		  struct lock_list **target_entry)
 {
 	int result;
 
-	debug_atomic_inc(nr_cyclic_checks);
-
-	result = __bfs_forwards(root, target, class_equal, target_entry);
-
-	return result;
-}
-
-static noinline int
-check_redundant(struct lock_list *root, struct lock_class *target,
-		struct lock_list **target_entry)
-{
-	int result;
-
-	debug_atomic_inc(nr_redundant_checks);
 
 	result = __bfs_forwards(root, target, class_equal, target_entry);
 
@@ -2235,7 +2224,8 @@ static void print_deadlock_scenario(struct held_lock *nxt,
 	 */
 	this.class = hlock_class(next);
 	this.parent = NULL;
-	ret = check_noncircular(&this, hlock_class(prev), &target_entry);
+	debug_atomic_inc(nr_cyclic_checks);
+	ret = check_nonexistent(&this, hlock_class(prev), &target_entry);
 	if (unlikely(!ret)) {
 		if (!trace->entries) {
 			/*
@@ -2287,7 +2277,8 @@ static void print_deadlock_scenario(struct held_lock *nxt,
 	 */
 	this.class = hlock_class(prev);
 	this.parent = NULL;
-	ret = check_redundant(&this, hlock_class(next), &target_entry);
+	debug_atomic_inc(nr_redundant_checks);
+	ret = check_nonexistent(&this, hlock_class(next), &target_entry);
 	if (!ret) {
 		debug_atomic_inc(nr_redundant);
 		return 2;
-- 
1.8.3.1