kthread: add __printf attributes

When commit fbae2d44aa1d ("kthread: add kthread_create_worker*()")
introduced some kthread_create_...() functions which were taking
printf-like parametter, it introduced __printf attributes to some
functions (e.g. kthread_create_worker()). Nevertheless some new
functions were forgotten (they have been detected thanks to
-Wmissing-format-attribute warning flag).

Add the missing __printf attributes to the newly-introduced functions in
order to detect formatting issues at build-time with -Wformat flag.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Nicolas Iooss <[e-mail]>
Reviewed-by: Petr Mladek <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/kthread.h

···
 struct kthread_worker *
 kthread_create_worker(unsigned int flags, const char namefmt[], ...);
 
-struct kthread_worker *
+__printf(3, 4) struct kthread_worker *
 kthread_create_worker_on_cpu(int cpu, unsigned int flags,
 			     const char namefmt[], ...);
 

kernel/kthread.c

···
 	}
 }
 
-static struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
+static __printf(4, 0)
+struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
 						    void *data, int node,
 						    const char namefmt[],
 						    va_list args)
···
 }
 EXPORT_SYMBOL_GPL(kthread_worker_fn);
 
-static struct kthread_worker *
+static __printf(3, 0) struct kthread_worker *
 __kthread_create_worker(int cpu, unsigned int flags,
 			const char namefmt[], va_list args)
 {