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From:   Xiongwei Song <sxwjean@me.com>
To:     peterz@infradead.org, mingo@redhat.com, will@kernel.org,
        longman@redhat.com, boqun.feng@gmail.com
Cc:     linux-kernel@vger.kernel.org, Xiongwei Song <sxwjean@gmail.com>
Subject: [PATCH v2 2/3] locking/lockdep: Unlikely conditons about BFS_RMATCH
Date:   Fri, 18 Jun 2021 22:55:33 +0800
Message-Id: <20210618145534.438816-3-sxwjean@me.com>
In-Reply-To: <20210618145534.438816-1-sxwjean@me.com>
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From: Xiongwei Song <sxwjean@gmail.com>

The probability that graph walk will return BFS_RMATCH is slim, so unlikey
conditons about BFS_RMATCH can improve performance a little bit.

Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
---
 kernel/locking/lockdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a8a66a2a9bc1..cb94097014d8 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2750,7 +2750,7 @@ check_redundant(struct held_lock *src, struct held_lock *target)
 	 */
 	ret = check_path(target, &src_entry, hlock_equal, usage_skip, &target_entry);
 
-	if (ret == BFS_RMATCH)
+	if (unlikely(ret == BFS_RMATCH))
 		debug_atomic_inc(nr_redundant);
 
 	return ret;
@@ -2992,7 +2992,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
 	ret = check_redundant(prev, next);
 	if (bfs_error(ret))
 		return 0;
-	else if (ret == BFS_RMATCH)
+	else if (unlikely(ret == BFS_RMATCH))
 		return 2;
 
 	if (!*trace) {
-- 
2.30.2