linux-kernel - [PATCH] kthread: Mark timer used by delayed kthread works as IRQ safe

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Message-Id: <20200217120709.1974-1-pmladek@suse.com>
Date:   Mon, 17 Feb 2020 13:07:09 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Tejun Heo <tj@...nel.org>,
        Grygorii Strashko <grygorii.strashko@...com>,
        linux-rt-users@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
        Richard Cochran <richardcochran@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH] 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.

Reported-by: Grygorii Strashko <grygorii.strashko@...com>
Signed-off-by: Petr Mladek <pmladek@...e.com>
Tested-by: Grygorii Strashko <grygorii.strashko@...com>
---
This patch is result of a discussion about using the API, see
https://lkml.kernel.org/r/cfa886ad-e3b7-c0d2-3ff8-58d94170eab5@ti.com

 include/linux/kthread.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 0f9da966934e..8bbcaad7ef0f 100644
--- 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);
-- 
2.16.4