2019-04-05 13:54:49

by Chengguang Xu

Subject: [PATCH] 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 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 <[email protected]>
Signed-off-by: Chengguang Xu <[email protected]>
---
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 df6a54045ac4..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

2019-04-25 19:51:29

by Greg Kroah-Hartman

Subject: Re: [PATCH] chardev: set variable ret to -EBUSY before checking minor range overlap

On Fri, Apr 05, 2019 at 09:53:06PM +0800, Chengguang Xu wrote:
> 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 <[email protected]>
> Signed-off-by: Chengguang Xu <[email protected]>
> ---
> fs/char_dev.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

What tree was this patch made against? I can't seem to apply it
anywhere :(

Please fix up and resend.

thanks,

greg k-h