linux-kernel - [PATCH] kobject: Refactor kobject_set_name

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Date:   Fri,  6 May 2022 19:03:09 +0530
From:   Jagdish Gediya <jvgediya@...ux.ibm.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, rafael@...nel.org,
        akpm@...ux-foundation.org
Cc:     keescook@...omium.org, andriy.shevchenko@...ux.intel.com,
        geert@...ux-m68k.org, linux@...ck-us.net, adobriyan@...il.com,
        Jagdish Gediya <jvgediya@...ux.ibm.com>
Subject: [PATCH] kobject: Refactor kobject_set_name_vargs()

Setting name as per the format is not only useful for kobjects.
It can also be used to set name for other things for e.g. setting
the name of the struct attribute when multiple same kind of attributes
need to be created with some identifier in name, instead of managing
memory for names at such places case by case, it would be good if
something like current kobject_set_name_vargs() can be utilized.

Refactor kobject_set_name_vargs(), Create a new generic function
set_name_vargs() which can be used for kobjects as well as at
other places.

This patch doesn't introduce any functionality change.

Signed-off-by: Jagdish Gediya <jvgediya@...ux.ibm.com>
---
 include/linux/string.h |  1 +
 lib/kobject.c          | 30 +-----------------------------
 mm/util.c              | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index b6572aeca2f5..f329962e5ae9 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -9,6 +9,7 @@
 #include <linux/stdarg.h>
 #include <uapi/linux/string.h>
 
+int set_name_vargs(const char **name, const char *fmt, va_list vargs);
 extern char *strndup_user(const char __user *, long);
 extern void *memdup_user(const void __user *, size_t);
 extern void *vmemdup_user(const void __user *, size_t);
diff --git a/lib/kobject.c b/lib/kobject.c
index 5f0e71ab292c..870d05971e3a 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -249,35 +249,7 @@ static int kobject_add_internal(struct kobject *kobj)
 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 				  va_list vargs)
 {
-	const char *s;
-
-	if (kobj->name && !fmt)
-		return 0;
-
-	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
-	if (!s)
-		return -ENOMEM;
-
-	/*
-	 * ewww... some of these buggers have '/' in the name ... If
-	 * that's the case, we need to make sure we have an actual
-	 * allocated copy to modify, since kvasprintf_const may have
-	 * returned something from .rodata.
-	 */
-	if (strchr(s, '/')) {
-		char *t;
-
-		t = kstrdup(s, GFP_KERNEL);
-		kfree_const(s);
-		if (!t)
-			return -ENOMEM;
-		strreplace(t, '/', '!');
-		s = t;
-	}
-	kfree_const(kobj->name);
-	kobj->name = s;
-
-	return 0;
+	return set_name_vargs(&kobj->name, fmt, vargs);
 }
 
 /**
diff --git a/mm/util.c b/mm/util.c
index 54e5e761a9a9..808d29b17ea7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -112,6 +112,46 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp)
 }
 EXPORT_SYMBOL(kstrndup);
 
+/**
+ * set_name_vargs() - Set the name as per format
+ * @name: pointer to point to the name as per format
+ * @fmt: format string used to build the name
+ * @vargs: vargs to format the string.
+ */
+int set_name_vargs(const char **name, const char *fmt, va_list vargs)
+{
+	const char *s;
+
+	if (*name && !fmt)
+		return 0;
+
+	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
+	if (!s)
+		return -ENOMEM;
+
+	/*
+	 * ewww... some of these buggers have '/' in the name ... If
+	 * that's the case, we need to make sure we have an actual
+	 * allocated copy to modify, since kvasprintf_const may have
+	 * returned something from .rodata.
+	 */
+	if (strchr(s, '/')) {
+		char *t;
+
+		t = kstrdup(s, GFP_KERNEL);
+		kfree_const(s);
+		if (!t)
+			return -ENOMEM;
+		strreplace(t, '/', '!');
+		s = t;
+	}
+	kfree_const(*name);
+	*name = s;
+
+	return 0;
+}
+EXPORT_SYMBOL(set_name_vargs);
+
 /**
  * kmemdup - duplicate region of memory
  *
-- 
2.35.1