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Commit dc4218bd authored by Christine Chan's avatar Christine Chan Committed by Thomas Gleixner
Browse files

timer: Use debugobjects to catch deletion of uninitialized timers 



del_timer_sync() calls debug_object_assert_init() to assert that
a timer has been initialized before calling lock_timer_base().
lock_timer_base() would spin forever on a NULL(uninit-ed) base.
The check is added to del_timer() to prevent silent failure, even
though it would not get stuck in an infinite loop.

[ sboyd@codeaurora.org: Remove WARN, intialize timer function]

Signed-off-by: default avatarChristine Chan <cschan@codeaurora.org>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1320724108-20788-4-git-send-email-sboyd@codeaurora.org


Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent fb16b8cf

kernel/timer.c

+48 −5
Original line number Diff line number Diff line
@@ -487,12 +487,40 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state) 
	}

}



/*

 * fixup_assert_init is called when:

 * - an untracked/uninit-ed object is found

 */

static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)

{

	struct timer_list *timer = addr;



	switch (state) {

	case ODEBUG_STATE_NOTAVAILABLE:

		if (timer->entry.prev == TIMER_ENTRY_STATIC) {

			/*

			 * This is not really a fixup. The timer was

			 * statically initialized. We just make sure that it

			 * is tracked in the object tracker.

			 */

			debug_object_init(timer, &timer_debug_descr);

			return 0;

		} else {

			setup_timer(timer, stub_timer, 0);

			return 1;

		}

	default:

		return 0;

	}

}



static struct debug_obj_descr timer_debug_descr = {

	.name			= "timer_list",

	.debug_hint		= timer_debug_hint,

	.fixup_init		= timer_fixup_init,

	.fixup_activate		= timer_fixup_activate,

	.fixup_free		= timer_fixup_free,

	.fixup_assert_init	= timer_fixup_assert_init,

};



static inline void debug_timer_init(struct timer_list *timer)
@@ -515,6 +543,11 @@ static inline void debug_timer_free(struct timer_list *timer) 
	debug_object_free(timer, &timer_debug_descr);

}



static inline void debug_timer_assert_init(struct timer_list *timer)

{

	debug_object_assert_init(timer, &timer_debug_descr);

}



static void __init_timer(struct timer_list *timer,

			 const char *name,

			 struct lock_class_key *key);
@@ -538,6 +571,7 @@ EXPORT_SYMBOL_GPL(destroy_timer_on_stack); 
static inline void debug_timer_init(struct timer_list *timer) { }

static inline void debug_timer_activate(struct timer_list *timer) { }

static inline void debug_timer_deactivate(struct timer_list *timer) { }

static inline void debug_timer_assert_init(struct timer_list *timer) { }

#endif



static inline void debug_init(struct timer_list *timer)
@@ -559,6 +593,11 @@ static inline void debug_deactivate(struct timer_list *timer) 
	trace_timer_cancel(timer);

}



static inline void debug_assert_init(struct timer_list *timer)

{

	debug_timer_assert_init(timer);

}



static void __init_timer(struct timer_list *timer,

			 const char *name,

			 struct lock_class_key *key)
@@ -909,6 +948,8 @@ int del_timer(struct timer_list *timer) 
	unsigned long flags;

	int ret = 0;



	debug_assert_init(timer);



	timer_stats_timer_clear_start_info(timer);

	if (timer_pending(timer)) {

		base = lock_timer_base(timer, &flags);
@@ -939,6 +980,8 @@ int try_to_del_timer_sync(struct timer_list *timer) 
	unsigned long flags;

	int ret = -1;



	debug_assert_init(timer);



	base = lock_timer_base(timer, &flags);



	if (base->running_timer == timer)