linux-kernel - [PATCH] lib/kobject: Simplify checking of parameters in kobj_ns_type

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Date:   Fri, 17 Jun 2022 16:38:32 +0800
From:   wuchi <wuchi.zero@...il.com>
To:     gregkh@...uxfoundation.org, rafael@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] lib/kobject: Simplify checking of parameters in kobj_ns_type_register.

1. Merge checking of following code:
    if (type >= KOBJ_NS_TYPES)
    ...
    if (type <= KOBJ_NS_TYPE_NONE)

2. Move the checking of parameters out of critical section, there is
no need to check that with spinlock.

Signed-off-by: wuchi <wuchi.zero@...il.com>
---
 lib/kobject.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/lib/kobject.c b/lib/kobject.c
index 5f0e71ab292c..6a8b009682b8 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -996,19 +996,13 @@ static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
 int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
 {
 	enum kobj_ns_type type = ops->type;
-	int error;
-
-	spin_lock(&kobj_ns_type_lock);
+	int error = -EBUSY;
 
-	error = -EINVAL;
-	if (type >= KOBJ_NS_TYPES)
-		goto out;
+	if (unlikely(type >= KOBJ_NS_TYPES || type <= KOBJ_NS_TYPE_NONE))
+		return -EINVAL;
 
-	error = -EINVAL;
-	if (type <= KOBJ_NS_TYPE_NONE)
-		goto out;
+	spin_lock(&kobj_ns_type_lock);
 
-	error = -EBUSY;
 	if (kobj_ns_ops_tbl[type])
 		goto out;
 
-- 
2.20.1