linux-kernel - [PATCH v2] Ucount: Optimize the ucount code

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Message-Id: <20240812084823.563277-1-xavier_qy@163.com>
Date: Mon, 12 Aug 2024 16:48:23 +0800
From: Xavier <xavier_qy@....com>
To: tglx@...utronix.de
Cc: anna-maria@...utronix.de,
	frederic@...nel.org,
	j.granados@...sung.com,
	kees@...nel.org,
	linux-kernel@...r.kernel.org,
	linux@...ssschuh.net,
	mcgrof@...nel.org,
	xavier_qy@....com
Subject: [PATCH v2] Ucount: Optimize the ucount code

Optimize the memory release operation by placing it outside of the
spin lock in alloc_ucounts.

Signed-off-by: Xavier <xavier_qy@....com>
---
 kernel/ucount.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/ucount.c b/kernel/ucount.c
index 8c07714ff27d..87a773e6ff15 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -164,7 +164,7 @@ struct ucounts *get_ucounts(struct ucounts *ucounts)
 struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
 {
 	struct hlist_head *hashent = ucounts_hashentry(ns, uid);
-	struct ucounts *ucounts, *new;
+	struct ucounts *ucounts, *new = NULL;
 	bool wrapped;
 
 	spin_lock_irq(&ucounts_lock);
@@ -182,9 +182,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
 
 		spin_lock_irq(&ucounts_lock);
 		ucounts = find_ucounts(ns, uid, hashent);
-		if (ucounts) {
-			kfree(new);
-		} else {
+		if (!ucounts) {
 			hlist_add_head(&new->node, hashent);
 			get_user_ns(new->ns);
 			spin_unlock_irq(&ucounts_lock);
@@ -193,6 +191,9 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
 	}
 	wrapped = !get_ucounts_or_wrap(ucounts);
 	spin_unlock_irq(&ucounts_lock);
+	if (new)
+		kfree(new);
+
 	if (wrapped) {
 		put_ucounts(ucounts);
 		return NULL;
-- 
2.45.2