linux-kernel - [PATCH 4/5] debugobjects: Use hlist_splice

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Message-ID: <20240902140532.2028-5-thunder.leizhen@huawei.com>
Date: Mon, 2 Sep 2024 22:05:31 +0800
From: Zhen Lei <thunder.leizhen@...wei.com>
To: Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner
	<tglx@...utronix.de>, <linux-kernel@...r.kernel.org>
CC: Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH 4/5] debugobjects: Use hlist_splice_init() to reduce lock conflicts

The sub list can be prepared in advance outside the lock, so that the
operation time inside the lock can be reduced and the possibility of
lock conflict can be reduced.

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 lib/debugobjects.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index fc8224f9f0eda8f..998724e9dee526b 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -167,23 +167,25 @@ static void fill_pool(void)
 		return;
 
 	while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {
-		struct debug_obj *new[ODEBUG_BATCH_SIZE];
+		HLIST_HEAD(batch_list);
+		struct debug_obj *new, *last;
 		int cnt;
 
 		for (cnt = 0; cnt < ODEBUG_BATCH_SIZE; cnt++) {
-			new[cnt] = kmem_cache_zalloc(obj_cache, gfp);
-			if (!new[cnt])
+			new = kmem_cache_zalloc(obj_cache, gfp);
+			if (!new)
 				break;
+			hlist_add_head(&new->node, &batch_list);
+			if (cnt == 0)
+				last = new;
 		}
 		if (!cnt)
 			return;
 
 		raw_spin_lock_irqsave(&pool_lock, flags);
-		while (cnt) {
-			hlist_add_head(&new[--cnt]->node, &obj_pool);
-			debug_objects_allocated++;
-			WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
-		}
+		hlist_splice_init(&batch_list, &last->node, &obj_pool);
+		debug_objects_allocated += cnt;
+		WRITE_ONCE(obj_pool_free, obj_pool_free + cnt);
 		raw_spin_unlock_irqrestore(&pool_lock, flags);
 	}
 }
-- 
2.34.1