From 317f29c14d0cca09952f1022491454b23455ebcb Mon Sep 17 00:00:00 2001

From: Stephen Boyd <swboyd@chromium.org>

Date: Wed, 11 May 2022 13:19:51 -0700

Subject: [PATCH] timers: Provide a better debugobjects hint for delayed works

Git-commit: 317f29c14d0cca09952f1022491454b23455ebcb

References: bsc#1207210

Patch-mainline: v5.19-rc1

With debugobjects enabled the timer hint for freeing of active timers

embedded inside delayed works is always the same, i.e. the hint is

delayed_work_timer_fn, even though the function the delayed work is going

to run can be wildly different depending on what work was queued.  Enabling

workqueue debugobjects doesn't help either because the delayed work isn't

considered active until it is actually queued to run on a workqueue. If the

work is freed while the timer is pending the work isn't considered active

so there is no information from workqueue debugobjects.

Special case delayed works in the timer debugobjects hint logic so that the

delayed work function is returned instead of the delayed_work_timer_fn.

This will help to understand which delayed work was pending that got

freed.

Apply the same treatment for kthread_delayed_work because it follows the

same pattern.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>

Signed-off-by: Stephen Boyd <swboyd@chromium.org>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Link: https://lore.kernel.org/r/20220511201951.42408-1-swboyd@chromium.org

Signed-off-by: Oliver Neukum <oneukum@suse.com>

---

 kernel/time/timer.c | 32 +++++++++++++++++++++++++++++++-

 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c

index ef082d43c307..a0666d948147 100644

--- a/kernel/time/timer.c

+++ b/kernel/time/timer.c

@@ -638,9 +638,39 @@ static void internal_add_timer(struct timer_base *base, struct timer_list *timer

 static const struct debug_obj_descr timer_debug_descr;

+struct timer_hint {

+	void	(*function)(struct timer_list *t);

+	long	offset;

+};

+

+#define TIMER_HINT(fn, container, timr, hintfn)			\

+	{							\

+		.function = fn,					\

+		.offset	  = offsetof(container, hintfn) -	\

+			    offsetof(container, timr)		\

+	}

+

+static const struct timer_hint timer_hints[] = {

+	TIMER_HINT(delayed_work_timer_fn,

+		   struct delayed_work, timer, work.func),

+	TIMER_HINT(kthread_delayed_work_timer_fn,

+		   struct kthread_delayed_work, timer, work.func),

+};

+

 static void *timer_debug_hint(void *addr)

 {

-	return ((struct timer_list *) addr)->function;

+	struct timer_list *timer = addr;

+	int i;

+

+	for (i = 0; i < ARRAY_SIZE(timer_hints); i++) {

+		if (timer_hints[i].function == timer->function) {

+			void (**fn)(void) = addr + timer_hints[i].offset;

+

+			return *fn;

+		}

+	}

+

+	return timer->function;

 }

 static bool timer_is_static_object(void *addr)

-- 

2.39.0