From a5abca2cd912406f3bbec9112dcc9a49aa8e3d86 Mon Sep 17 00:00:00 2001 From: Christine Chan Date: Tue, 8 Nov 2011 11:20:02 +1100 Subject: [PATCH] kernel/timer.c: 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. Signed-off-by: Christine Chan Cc: Thomas Gleixner Cc: John Stultz Signed-off-by: Andrew Morton --- kernel/timer.c | 54 +++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) diff --git a/kernel/timer.c b/kernel/timer.c index dbaa62422b13..42d02c1e877d 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -480,12 +480,41 @@ 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 { + WARN_ON(1); + init_timer(timer); + 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, + .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) @@ -508,6 +537,11 @@ 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); @@ -531,6 +565,7 @@ 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) @@ -552,6 +587,11 @@ 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) @@ -902,6 +942,8 @@ 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); @@ -932,6 +974,8 @@ 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) -- 2.39.5