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From:   Chengguang Xu <cgxu519@gmx.com>
To:     gregkh@linuxfoundation.org
Cc:     dan.carpenter@oracle.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, Chengguang Xu <cgxu519@gmx.com>
Subject: [RESEND PATCH] chardev: set variable ret to -EBUSY before checking minor range overlap
Date:   Fri, 26 Apr 2019 15:38:37 +0800
Message-Id: <20190426073837.23086-1-cgxu519@gmx.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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 chekcking
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@oracle.com>
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
=2D--
 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
=2D-- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -98,7 +98,7 @@ __register_chrdev_region(unsigned int major, unsigned in=
t baseminor,
 			   int minorct, const char *name)
 {
 	struct char_device_struct *cd, *curr, *prev =3D NULL;
-	int ret =3D -EBUSY;
+	int ret;
 	int i;

 	if (major >=3D CHRDEV_MAJOR_MAX) {
@@ -129,6 +129,7 @@ __register_chrdev_region(unsigned int major, unsigned =
int baseminor,
 		major =3D ret;
 	}

+	ret =3D -EBUSY;
 	i =3D major_to_index(major);
 	for (curr =3D chrdevs[i]; curr; prev =3D curr, curr =3D curr->next) {
 		if (curr->major < major)
=2D-
2.20.1