linux-kernel - [PATCH 3/3] locking/lockdep: print possible warning after counting deps

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Date:   Thu, 17 Jun 2021 22:28:28 +0800
From:   Xiongwei Song <sxwjean@...com>
To:     peterz@...radead.org, mingo@...hat.com, will@...nel.org,
        longman@...hat.com, boqun.feng@...il.com
Cc:     linux-kernel@...r.kernel.org, Xiongwei Song <sxwjean@...il.com>
Subject: [PATCH 3/3] locking/lockdep: print possible warning after counting deps

From: Xiongwei Song <sxwjean@...il.com>

The graph walk might hit error when counting dependencies. Once the
return value is negative, print a warning to reminder users.

Suggested-by: Waiman Long <longman@...hat.com>
Signed-off-by: Xiongwei Song <sxwjean@...il.com>
---
 kernel/locking/lockdep.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index cb94097014d8..cfe0f4374594 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2028,8 +2028,12 @@ static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
 {
 	unsigned long  count = 0;
 	struct lock_list *target_entry;
+	enum bfs_result ret;
+
+	ret = __bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
 
-	__bfs_forwards(this, (void *)&count, noop_count, NULL, &target_entry);
+	if (bfs_error(ret))
+		print_bfs_bug(ret);
 
 	return count;
 }
@@ -2053,8 +2057,12 @@ static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
 {
 	unsigned long  count = 0;
 	struct lock_list *target_entry;
+	enum bfs_result ret;
+
+	ret = __bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
 
-	__bfs_backwards(this, (void *)&count, noop_count, NULL, &target_entry);
+	if (bfs_error(ret))
+		print_bfs_bug(ret);
 
 	return count;
 }
-- 
2.30.2