kthread: mark timer used by delayed kthread works as IRQ safe

The timer used by delayed kthread works are IRQ safe because the used
kthread_delayed_work_timer_fn() is IRQ safe.

It is properly marked when initialized by KTHREAD_DELAYED_WORK_INIT().
But TIMER_IRQSAFE flag is missing when initialized by
kthread_init_delayed_work().

The missing flag might trigger invalid warning from del_timer_sync() when
kthread_mod_delayed_work() is called with interrupts disabled.

This patch is result of a discussion about using the API, see
https://lkml.kernel.org/r/cfa886ad-e3b7-c0d2-3ff8-58d94170eab5@ti.com

Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200217120709.1974-1-pmladek@suse.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 0f9da96..8bbcaad 100644 (file)
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -165,7 +165,8 @@ extern void __kthread_init_worker(struct kthread_worker *worker,
        do {                                                            \
                kthread_init_work(&(dwork)->work, (fn));                \
                timer_setup(&(dwork)->timer,                            \
-                            kthread_delayed_work_timer_fn, 0);         \
+                            kthread_delayed_work_timer_fn,             \
+                            TIMER_IRQSAFE);                            \
        } while (0)
 
 int kthread_worker_fn(void *worker_ptr);