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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 1/3] locking/lockdep: Unlikely bfs_error() inside
Date: Fri, 18 Jun 2021 22:55:32 +0800	[thread overview]
Message-ID: <20210618145534.438816-2-sxwjean@me.com> (raw)
In-Reply-To: <20210618145534.438816-1-sxwjean@me.com>

From: Xiongwei Song <sxwjean@gmail.com>

The error from graph walk is small probability event, and there are some
bfs_error calls during lockdep detection, so unlikely bfs_error inside
can improve performance a little bit.

Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
---
 kernel/locking/lockdep.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 7641bd407239..a8a66a2a9bc1 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1540,7 +1540,7 @@ enum bfs_result {
  */
 static inline bool bfs_error(enum bfs_result res)
 {
-	return res < 0;
+	return unlikely(res < 0);
 }
 
 /*
@@ -2089,7 +2089,7 @@ check_path(struct held_lock *target, struct lock_list *src_entry,
 
 	ret = __bfs_forwards(src_entry, target, match, skip, target_entry);
 
-	if (unlikely(bfs_error(ret)))
+	if (bfs_error(ret))
 		print_bfs_bug(ret);
 
 	return ret;
@@ -2936,7 +2936,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
 	 * in the graph whose neighbours are to be checked.
 	 */
 	ret = check_noncircular(next, prev, trace);
-	if (unlikely(bfs_error(ret) || ret == BFS_RMATCH))
+	if (bfs_error(ret) || unlikely(ret == BFS_RMATCH))
 		return 0;
 
 	if (!check_irq_usage(curr, prev, next))
-- 
2.30.2


  reply	other threads:[~2021-06-18 14:56 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 14:55 [PATCH v2 0/3] some improvements for lockdep Xiongwei Song
2021-06-18 14:55 ` Xiongwei Song [this message]
2021-06-18 14:55 ` [PATCH v2 2/3] locking/lockdep: Unlikely conditons about BFS_RMATCH Xiongwei Song
2021-06-18 14:55 ` [PATCH v2 3/3] locking/lockdep: Print possible warning after counting deps Xiongwei Song
2021-06-24  8:03   ` Xiongwei Song
2021-06-24 13:45   ` Boqun Feng
2021-07-12  8:19 ` [PATCH v2 0/3] some improvements for lockdep Xiongwei Song

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