linux-kernel - [PATCH v1] Namespace: Optimize the namespace code

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Message-Id: <20240809121732.545807-1-xavier_qy@163.com>
Date: Fri,  9 Aug 2024 20:17:32 +0800
From: Xavier <xavier_qy@....com>
To: anna-maria@...utronix.de,
	frederic@...nel.org,
	tglx@...utronix.de,
	j.granados@...sung.com,
	linux@...ssschuh.net,
	mcgrof@...nel.org,
	kees@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Xavier <xavier_qy@....com>
Subject: [PATCH v1] Namespace: Optimize the namespace code

Modify variable names in the function clone_time_ns to enhance
readability, and optimize the memory release operation by placing
it outside of the spin lock in alloc_ucounts.

Signed-off-by: Xavier <xavier_qy@....com>
---
 kernel/time/namespace.c | 30 +++++++++++++++---------------
 kernel/ucount.c         |  9 +++++----
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 0775b9ec952a..4c0836fb845b 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -78,7 +78,7 @@ static void dec_time_namespaces(struct ucounts *ucounts)
 static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 					  struct time_namespace *old_ns)
 {
-	struct time_namespace *ns;
+	struct time_namespace *time_ns;
 	struct ucounts *ucounts;
 	int err;
 
@@ -88,31 +88,31 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 		goto fail;
 
 	err = -ENOMEM;
-	ns = kmalloc(sizeof(*ns), GFP_KERNEL_ACCOUNT);
-	if (!ns)
+	time_ns = kmalloc(sizeof(*time_ns), GFP_KERNEL_ACCOUNT);
+	if (!time_ns)
 		goto fail_dec;
 
-	refcount_set(&ns->ns.count, 1);
+	refcount_set(&time_ns->ns.count, 1);
 
-	ns->vvar_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
-	if (!ns->vvar_page)
+	time_ns->vvar_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	if (!time_ns->vvar_page)
 		goto fail_free;
 
-	err = ns_alloc_inum(&ns->ns);
+	err = ns_alloc_inum(&time_ns->ns);
 	if (err)
 		goto fail_free_page;
 
-	ns->ucounts = ucounts;
-	ns->ns.ops = &timens_operations;
-	ns->user_ns = get_user_ns(user_ns);
-	ns->offsets = old_ns->offsets;
-	ns->frozen_offsets = false;
-	return ns;
+	time_ns->ucounts = ucounts;
+	time_ns->ns.ops = &timens_operations;
+	time_ns->user_ns = get_user_ns(user_ns);
+	time_ns->offsets = old_ns->offsets;
+	time_ns->frozen_offsets = false;
+	return time_ns;
 
 fail_free_page:
-	__free_page(ns->vvar_page);
+	__free_page(time_ns->vvar_page);
 fail_free:
-	kfree(ns);
+	kfree(time_ns);
 fail_dec:
 	dec_time_namespaces(ucounts);
 fail:
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