linux-kernel - [PATCH v2] chardev: set variable ret to -EBUSY before checking minor range overlap

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Message-Id: <1556799305-13288-1-git-send-email-cgxu519@gmail.com>
Date:   Thu,  2 May 2019 20:15:05 +0800
From:   Chengguang Xu <cgxu519@...il.com>
To:     gregkh@...uxfoundation.org, dan.carpenter@...cle.com
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Chengguang Xu <cgxu519@...il.com>
Subject: [PATCH v2] chardev: set variable ret to -EBUSY before checking minor range overlap

When allocating dynamic major, the minor range overlap check
in __register_chrdev_region() will not fail, so actually
there is no real case to passing non negative error code to
caller. However, set variable ret to -EBUSY before checking
minor range overlap will avoid false-positive warning from
code analyzing tool(like Smatch) and also make the code more
easy to understand.

Suggested-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Chengguang Xu <cgxu519@...il.com>
---
v1->v2:
- Rebase against the latest char-misc-next.
- Modify signed-off mail address.

 fs/char_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/char_dev.c b/fs/char_dev.c
index d18cad28c1c3..00dfe17871ac 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -98,7 +98,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 			   int minorct, const char *name)
 {
 	struct char_device_struct *cd, *curr, *prev = NULL;
-	int ret = -EBUSY;
+	int ret;
 	int i;
 
 	if (major >= CHRDEV_MAJOR_MAX) {
@@ -129,6 +129,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 		major = ret;
 	}
 
+	ret = -EBUSY;
 	i = major_to_index(major);
 	for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {
 		if (curr->major < major)
-- 
2.17.2