kmod: always provide usermodehelper_disable()

We need to prevent kernel-forked processes during system poweroff.
Such processes try to access the filesystem whose disks we are
trying to shutdown at the same time. This causes delays and exceptions
in the storage drivers.

A follow-up patch will add these calls and need usermodehelper_disable()
also on systems without suspend support.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

include/linux/kmod.h

@@ -111,12 +111,8 @@ call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
 
 extern void usermodehelper_init(void);
 
-#ifdef CONFIG_PM_SLEEP
 extern int usermodehelper_disable(void);
 extern void usermodehelper_enable(void);
 extern bool usermodehelper_is_disabled(void);
-#else
-static inline bool usermodehelper_is_disabled(void) { return false; }
-#endif
 
 #endif /* __LINUX_KMOD_H__ */

kernel/kmod.c

@@ -245,7 +245,6 @@ static void __call_usermodehelper(struct work_struct *work)
 	}
 }
 
-#ifdef CONFIG_PM_SLEEP
 /*
  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
  * (used for preventing user land processes from being created after the user
@@ -321,12 +320,6 @@ static void helper_unlock(void)
 	if (atomic_dec_and_test(&running_helpers))
 		wake_up(&running_helpers_waitq);
 }
-#else /* CONFIG_PM_SLEEP */
-#define usermodehelper_disabled	0
-
-static inline void helper_lock(void) {}
-static inline void helper_unlock(void) {}
-#endif /* CONFIG_PM_SLEEP */
 
 /**
  * call_usermodehelper_setup - prepare to call a usermode helper