linux-kernel - [PATCH v3 2/4] kernel: refactor lookup_or_create_module

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Message-Id: <20250211214842.1806521-3-shyamsaini@linux.microsoft.com>
Date: Tue, 11 Feb 2025 13:48:40 -0800
From: Shyam Saini <shyamsaini@...ux.microsoft.com>
To: linux-kernel@...r.kernel.org,
	linux-modules@...r.kernel.org
Cc: code@...icks.com,
	linux@...musvillemoes.dk,
	christophe.leroy@...roup.eu,
	hch@...radead.org,
	mcgrof@...nel.org,
	frkaya@...ux.microsoft.com,
	vijayb@...ux.microsoft.com,
	petr.pavlu@...e.com,
	linux@...ssschuh.net,
	samitolvanen@...gle.com,
	da.gomez@...sung.com,
	gregkh@...uxfoundation.org,
	rafael@...nel.org,
	dakr@...nel.org
Subject: [PATCH v3 2/4] kernel: refactor lookup_or_create_module_kobject()

In the unlikely event of the allocation failing, it is better to let
the machine boot with a not fully populated sysfs than to kill it with
this BUG_ON(). All callers are already prepared for
lookup_or_create_module_kobject() returning NULL.

This is also preparation for calling this function from non __init
code, where using BUG_ON for allocation failure handling is not
acceptable.

Since we are here, also start using IS_ENABLED instead of #ifdef
construct.

Suggested-by: Thomas Weißschuh <linux@...ssschuh.net>
Suggested-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Signed-off-by: Shyam Saini <shyamsaini@...ux.microsoft.com>
---
 kernel/params.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/kernel/params.c b/kernel/params.c
index 4b43baaf7c83..6e87aef876b2 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -770,31 +770,28 @@ static struct module_kobject * __init lookup_or_create_module_kobject(const char
 	int err;
 
 	kobj = kset_find_obj(module_kset, name);
-	if (kobj) {
-		mk = to_module_kobject(kobj);
-	} else {
-		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
-		BUG_ON(!mk);
-
-		mk->mod = THIS_MODULE;
-		mk->kobj.kset = module_kset;
-		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
-					   "%s", name);
-#ifdef CONFIG_MODULES
-		if (!err)
-			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
-#endif
-		if (err) {
-			kobject_put(&mk->kobj);
-			pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
-				name, err);
-			return NULL;
-		}
+	if (kobj)
+		return to_module_kobject(kobj);
 
-		/* So that we hold reference in both cases. */
-		kobject_get(&mk->kobj);
+	mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
+	if (!mk)
+		return NULL;
+
+	mk->mod = THIS_MODULE;
+	mk->kobj.kset = module_kset;
+	err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL, "%s", name);
+	if (IS_ENABLED(CONFIG_MODULES) && !err)
+		err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
+	if (err) {
+		kobject_put(&mk->kobj);
+		pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
+			name, err);
+		return NULL;
 	}
 
+	/* So that we hold reference in both cases. */
+	kobject_get(&mk->kobj);
+
 	return mk;
 }
 
-- 
2.34.1