2017-06-02 12:07:27

by Corentin Labbe

Subject: [PATCH] kernel/module.c: fix warning about unused nowarn variable

This patch fix the following warning:
kernel/module.c: In function 'add_usage_links':
kernel/module.c:1653:6: warning: variable 'nowarn' set but not used [-Wunused-but-set-variable]
int nowarn;

Signed-off-by: Corentin Labbe <[email protected]>
---
kernel/module.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index e3e9dbba6a5b..aed902bcb4aa 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1663,19 +1663,20 @@ static inline void remove_notes_attrs(struct module *mod)
}
#endif /* CONFIG_KALLSYMS */

-static void add_usage_links(struct module *mod)
+static int add_usage_links(struct module *mod)
{
+ int ret = 0;
#ifdef CONFIG_MODULE_UNLOAD
struct module_use *use;
- int nowarn;

mutex_lock(&module_mutex);
list_for_each_entry(use, &mod->target_list, target_list) {
- nowarn = sysfs_create_link(use->target->holders_dir,
+ ret = sysfs_create_link(use->target->holders_dir,
&mod->mkobj.kobj, mod->name);
}
mutex_unlock(&module_mutex);
#endif
+ return ret;
}

static void del_usage_links(struct module *mod)
@@ -1798,13 +1799,17 @@ static int mod_sysfs_setup(struct module *mod,
if (err)
goto out_unreg_param;

- add_usage_links(mod);
+ err = add_usage_links(mod);
+ if (err)
+ goto out_unreg_usage_links;
add_sect_attrs(mod, info);
add_notes_attrs(mod, info);

kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
return 0;

+out_unreg_usage_links:
+ module_remove_modinfo_attrs(mod);
out_unreg_param:
module_param_sysfs_remove(mod);
out_unreg_holders:
--
2.13.0

2017-06-06 05:09:27

by Jessica Yu

Subject: Re: [PATCH] kernel/module.c: fix warning about unused nowarn variable

+++ Corentin Labbe [02/06/17 14:05 +0200]:
>This patch fix the following warning:
>kernel/module.c: In function 'add_usage_links':
>kernel/module.c:1653:6: warning: variable 'nowarn' set but not used [-Wunused-but-set-variable]
> int nowarn;
>
>Signed-off-by: Corentin Labbe <[email protected]>
>---
> kernel/module.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index e3e9dbba6a5b..aed902bcb4aa 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -1663,19 +1663,20 @@ static inline void remove_notes_attrs(struct module *mod)
> }
> #endif /* CONFIG_KALLSYMS */
>
>-static void add_usage_links(struct module *mod)
>+static int add_usage_links(struct module *mod)
> {
>+ int ret = 0;
> #ifdef CONFIG_MODULE_UNLOAD
> struct module_use *use;
>- int nowarn;
>
> mutex_lock(&module_mutex);
> list_for_each_entry(use, &mod->target_list, target_list) {
>- nowarn = sysfs_create_link(use->target->holders_dir,
>+ ret = sysfs_create_link(use->target->holders_dir,
> &mod->mkobj.kobj, mod->name);

ret will get overwritten with each iteration of the loop; we should return
ret as soon as we hit an error (while making sure we unlock
module_mutex).

> }
> mutex_unlock(&module_mutex);
> #endif
>+ return ret;
> }
>
> static void del_usage_links(struct module *mod)
>@@ -1798,13 +1799,17 @@ static int mod_sysfs_setup(struct module *mod,
> if (err)
> goto out_unreg_param;
>
>- add_usage_links(mod);
>+ err = add_usage_links(mod);
>+ if (err)
>+ goto out_unreg_usage_links;

Small nitpick: could you add an extra newline here?

> add_sect_attrs(mod, info);
> add_notes_attrs(mod, info);
>
> kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD);
> return 0;
>
>+out_unreg_usage_links:

Can you rename this to `out_unreg_modinfo_attrs` (to better reflect
what's being done)?

>+ module_remove_modinfo_attrs(mod);
> out_unreg_param:
> module_param_sysfs_remove(mod);
> out_unreg_holders:

Thanks,

Jessica

2017-06-06 06:39:06

by Corentin Labbe

Subject: Re: [PATCH] kernel/module.c: fix warning about unused nowarn variable

On Mon, Jun 05, 2017 at 10:09:24PM -0700, Jessica Yu wrote:
> +++ Corentin Labbe [02/06/17 14:05 +0200]:
> >This patch fix the following warning:
> >kernel/module.c: In function 'add_usage_links':
> >kernel/module.c:1653:6: warning: variable 'nowarn' set but not used [-Wunused-but-set-variable]
> > int nowarn;
> >
> >Signed-off-by: Corentin Labbe <[email protected]>
> >---
> > kernel/module.c | 13 +++++++++----
> > 1 file changed, 9 insertions(+), 4 deletions(-)
> >
> >diff --git a/kernel/module.c b/kernel/module.c
> >index e3e9dbba6a5b..aed902bcb4aa 100644
> >--- a/kernel/module.c
> >+++ b/kernel/module.c
> >@@ -1663,19 +1663,20 @@ static inline void remove_notes_attrs(struct module *mod)
> > }
> > #endif /* CONFIG_KALLSYMS */
> >
> >-static void add_usage_links(struct module *mod)
> >+static int add_usage_links(struct module *mod)
> > {
> >+ int ret = 0;
> > #ifdef CONFIG_MODULE_UNLOAD
> > struct module_use *use;
> >- int nowarn;
> >
> > mutex_lock(&module_mutex);
> > list_for_each_entry(use, &mod->target_list, target_list) {
> >- nowarn = sysfs_create_link(use->target->holders_dir,
> >+ ret = sysfs_create_link(use->target->holders_dir,
> > &mod->mkobj.kobj, mod->name);
>
> ret will get overwritten with each iteration of the loop; we should return
> ret as soon as we hit an error (while making sure we unlock
> module_mutex).
>

Thanks, I will fix all reported errors.
I just found also that in case of error, I need to "del_usage_links"

Regards