[PATCH -next] driver core: Remove set but not used variable 'no_warn'

[PATCH -next] driver core: Remove set but not used variable 'no_warn'

[Baokun Li]

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/base/module.c: In function 'module_create_drivers_dir':
drivers/base/module.c:36:6: warning:
 variable ‘no_warn’ set but not used [-Wunused-but-set-variable]

It never used since introduction.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
---
 drivers/base/module.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/base/module.c b/drivers/base/module.c
index 46ad4d636731..07ecd66b12b0 100644
--- a/drivers/base/module.c
+++ b/drivers/base/module.c
@@ -33,7 +33,6 @@ static void module_create_drivers_dir(struct module_kobject *mk)
 void module_add_driver(struct module *mod, struct device_driver *drv)
 {
 	char *driver_name;
-	int no_warn;
 	struct module_kobject *mk = NULL;
 
 	if (!drv)
@@ -59,12 +58,12 @@ void module_add_driver(struct module *mod, struct device_driver *drv)
 		return;
 
 	/* Don't check return codes; these calls are idempotent */
-	no_warn = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
+	sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
 	driver_name = make_driver_name(drv);
 	if (driver_name) {
 		module_create_drivers_dir(mk);
-		no_warn = sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
-					    driver_name);
+		sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
+				  driver_name);
 		kfree(driver_name);
 	}
 }
-- 
2.25.4

Re: [PATCH -next] driver core: Remove set but not used variable 'no_warn'

[Greg KH]

On Thu, May 27, 2021 at 05:14:53PM +0800, Baokun Li wrote:
> Fixes gcc '-Wunused-but-set-variable' warning:
> 
> drivers/base/module.c: In function 'module_create_drivers_dir':
> drivers/base/module.c:36:6: warning:
>  variable ‘no_warn’ set but not used [-Wunused-but-set-variable]
> 
> It never used since introduction.
> 
> Signed-off-by: Baokun Li <libaokun1@huawei.com>
> ---
>  drivers/base/module.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/base/module.c b/drivers/base/module.c
> index 46ad4d636731..07ecd66b12b0 100644
> --- a/drivers/base/module.c
> +++ b/drivers/base/module.c
> @@ -33,7 +33,6 @@ static void module_create_drivers_dir(struct module_kobject *mk)
>  void module_add_driver(struct module *mod, struct device_driver *drv)
>  {
>  	char *driver_name;
> -	int no_warn;
>  	struct module_kobject *mk = NULL;
>  
>  	if (!drv)
> @@ -59,12 +58,12 @@ void module_add_driver(struct module *mod, struct device_driver *drv)
>  		return;
>  
>  	/* Don't check return codes; these calls are idempotent */
> -	no_warn = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
> +	sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
>  	driver_name = make_driver_name(drv);
>  	if (driver_name) {
>  		module_create_drivers_dir(mk);
> -		no_warn = sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
> -					    driver_name);
> +		sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
> +				  driver_name);
>  		kfree(driver_name);
>  	}
>  }
> -- 
> 2.25.4
>

And now you have a build warning :(

Please always test-build your patches before sending them out.

greg k-h

Re: [PATCH -next] driver core: Remove set but not used variable 'no_warn'

[kernel test robot]

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Hi Baokun,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on next-20210526]

url:    https://github.com/0day-ci/linux/commits/Baokun-Li/driver-core-Remove-set-but-not-used-variable-no_warn/20210527-170758
base:    f6b46ef27317b3441138b902689bd89e4f82c6f4
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/c41d30a4b7791bb76211dd1ddb7b467d555ad596
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Baokun-Li/driver-core-Remove-set-but-not-used-variable-no_warn/20210527-170758
        git checkout c41d30a4b7791bb76211dd1ddb7b467d555ad596
        # save the attached .config to linux build tree
        make W=1 ARCH=um SUBARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/base/module.c: In function 'module_add_driver':
>> drivers/base/module.c:61:2: warning: ignoring return value of 'sysfs_create_link', declared with attribute warn_unused_result [-Wunused-result]
      61 |  sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
         |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/base/module.c:65:3: warning: ignoring return value of 'sysfs_create_link', declared with attribute warn_unused_result [-Wunused-result]
      65 |   sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
         |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      66 |       driver_name);
         |       ~~~~~~~~~~~~


vim +/sysfs_create_link +61 drivers/base/module.c

    32	
    33	void module_add_driver(struct module *mod, struct device_driver *drv)
    34	{
    35		char *driver_name;
    36		struct module_kobject *mk = NULL;
    37	
    38		if (!drv)
    39			return;
    40	
    41		if (mod)
    42			mk = &mod->mkobj;
    43		else if (drv->mod_name) {
    44			struct kobject *mkobj;
    45	
    46			/* Lookup built-in module entry in /sys/modules */
    47			mkobj = kset_find_obj(module_kset, drv->mod_name);
    48			if (mkobj) {
    49				mk = container_of(mkobj, struct module_kobject, kobj);
    50				/* remember our module structure */
    51				drv->p->mkobj = mk;
    52				/* kset_find_obj took a reference */
    53				kobject_put(mkobj);
    54			}
    55		}
    56	
    57		if (!mk)
    58			return;
    59	
    60		/* Don't check return codes; these calls are idempotent */
  > 61		sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
    62		driver_name = make_driver_name(drv);
    63		if (driver_name) {
    64			module_create_drivers_dir(mk);
    65			sysfs_create_link(mk->drivers_dir, &drv->p->kobj,
    66					  driver_name);
    67			kfree(driver_name);
    68		}
    69	}
    70	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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