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From: Zhihao Cheng <chengzhihao1@huawei.com>
To: <richard@nod.at>, <miquel.raynal@bootlin.com>, <ben.hutchings@mind.be>,
	<daniel@makrotopia.org>
CC: <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 2/4] ubi: ubi_init: Fix missed ubiblock cleanup in error handling path
Date: Thu, 11 Apr 2024 11:19:01 +0800
Message-ID: <20240411031903.3050278-3-chengzhihao1@huawei.com>
In-Reply-To: <20240411031903.3050278-1-chengzhihao1@huawei.com>
References: <20240411031903.3050278-1-chengzhihao1@huawei.com>
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The ubiblock_init called by ubi_init will register device number, but
device number is not released in error handling path of ubi_init when
ubi is loaded by inserting module (eg. attaching failure), which leads
to subsequent ubi_init calls failed by running out of device number
(dmesg shows that "__register_blkdev: failed to get major for ubiblock").
Since ubiblock_init() registers notifier and invokes notification
functions, so we can move it after ubi_init_attach() to fix the problem.

Fixes: 927c145208b0 ("mtd: ubi: attach from device tree")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 drivers/mtd/ubi/build.c | 51 +++++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 7f95fd7968a8..bc63fbf5e947 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -1263,9 +1263,21 @@ static struct mtd_notifier ubi_mtd_notifier = {
 	.remove = ubi_notify_remove,
 };
 
+static void detach_mtd_devs(int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		if (ubi_devices[i]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+}
+
 static int __init ubi_init_attach(void)
 {
-	int err, i, k;
+	int err, i;
 
 	/* Attach MTD devices */
 	for (i = 0; i < mtd_devs; i++) {
@@ -1317,12 +1329,7 @@ static int __init ubi_init_attach(void)
 	return 0;
 
 out_detach:
-	for (k = 0; k < i; k++)
-		if (ubi_devices[k]) {
-			mutex_lock(&ubi_devices_mutex);
-			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
-			mutex_unlock(&ubi_devices_mutex);
-		}
+	detach_mtd_devs(i);
 	return err;
 }
 #ifndef CONFIG_MTD_UBI_MODULE
@@ -1366,15 +1373,6 @@ static int __init ubi_init(void)
 	if (err)
 		goto out_slab;
 
-	err = ubiblock_init();
-	if (err) {
-		pr_err("UBI error: block: cannot initialize, error %d\n", err);
-
-		/* See comment above re-ubi_is_module(). */
-		if (ubi_is_module())
-			goto out_debugfs;
-	}
-
 	register_mtd_user(&ubi_mtd_notifier);
 
 	if (ubi_is_module()) {
@@ -1383,11 +1381,21 @@ static int __init ubi_init(void)
 			goto out_mtd_notifier;
 	}
 
+	err = ubiblock_init();
+	if (err) {
+		pr_err("UBI error: block: cannot initialize, error %d\n", err);
+
+		/* See comment above re-ubi_is_module(). */
+		if (ubi_is_module())
+			goto out_detach;
+	}
+
 	return 0;
 
+out_detach:
+	detach_mtd_devs(mtd_devs);
 out_mtd_notifier:
 	unregister_mtd_user(&ubi_mtd_notifier);
-out_debugfs:
 	ubi_debugfs_exit();
 out_slab:
 	kmem_cache_destroy(ubi_wl_entry_slab);
@@ -1403,17 +1411,10 @@ device_initcall(ubi_init);
 
 static void __exit ubi_exit(void)
 {
-	int i;
-
 	ubiblock_exit();
 	unregister_mtd_user(&ubi_mtd_notifier);
 
-	for (i = 0; i < UBI_MAX_DEVICES; i++)
-		if (ubi_devices[i]) {
-			mutex_lock(&ubi_devices_mutex);
-			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
-			mutex_unlock(&ubi_devices_mutex);
-		}
+	detach_mtd_devs(UBI_MAX_DEVICES);
 	ubi_debugfs_exit();
 	kmem_cache_destroy(ubi_wl_entry_slab);
 	misc_deregister(&ubi_ctrl_cdev);
-- 
2.39.2