From 6f2b9b9a9d750a9175dc79c74bfed5add840983c Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 29 Jan 2009 16:03:20 +0100 Subject: timer: implement lockdep deadlock detection This modifies the timer code in a way to allow lockdep to detect deadlocks resulting from a lock being taken in the timer function as well as around the del_timer_sync() call. Signed-off-by: Johannes Berg --- include/linux/timer.h | 93 ++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 84 insertions(+), 9 deletions(-) (limited to 'include/linux/timer.h') diff --git a/include/linux/timer.h b/include/linux/timer.h index daf9685b861c..51774eb87cc6 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -5,6 +5,7 @@ #include #include #include +#include struct tvec_base; @@ -21,52 +22,126 @@ struct timer_list { char start_comm[16]; int start_pid; #endif +#ifdef CONFIG_LOCKDEP + struct lockdep_map lockdep_map; +#endif }; extern struct tvec_base boot_tvec_bases; +#ifdef CONFIG_LOCKDEP +/* + * NB: because we have to copy the lockdep_map, setting the lockdep_map key + * (second argument) here is required, otherwise it could be initialised to + * the copy of the lockdep_map later! We use the pointer to and the string + * ":" as the key resp. the name of the lockdep_map. + */ +#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn) \ + .lockdep_map = STATIC_LOCKDEP_MAP_INIT(_kn, &_kn), +#else +#define __TIMER_LOCKDEP_MAP_INITIALIZER(_kn) +#endif + #define TIMER_INITIALIZER(_function, _expires, _data) { \ .entry = { .prev = TIMER_ENTRY_STATIC }, \ .function = (_function), \ .expires = (_expires), \ .data = (_data), \ .base = &boot_tvec_bases, \ + __TIMER_LOCKDEP_MAP_INITIALIZER( \ + __FILE__ ":" __stringify(__LINE__)) \ } #define DEFINE_TIMER(_name, _function, _expires, _data) \ struct timer_list _name = \ TIMER_INITIALIZER(_function, _expires, _data) -void init_timer(struct timer_list *timer); -void init_timer_deferrable(struct timer_list *timer); +void init_timer_key(struct timer_list *timer, + const char *name, + struct lock_class_key *key); +void init_timer_deferrable_key(struct timer_list *timer, + const char *name, + struct lock_class_key *key); + +#ifdef CONFIG_LOCKDEP +#define init_timer(timer) \ + do { \ + static struct lock_class_key __key; \ + init_timer_key((timer), #timer, &__key); \ + } while (0) + +#define init_timer_deferrable(timer) \ + do { \ + static struct lock_class_key __key; \ + init_timer_deferrable_key((timer), #timer, &__key); \ + } while (0) + +#define init_timer_on_stack(timer) \ + do { \ + static struct lock_class_key __key; \ + init_timer_on_stack_key((timer), #timer, &__key); \ + } while (0) + +#define setup_timer(timer, fn, data) \ + do { \ + static struct lock_class_key __key; \ + setup_timer_key((timer), #timer, &__key, (fn), (data));\ + } while (0) + +#define setup_timer_on_stack(timer, fn, data) \ + do { \ + static struct lock_class_key __key; \ + setup_timer_on_stack_key((timer), #timer, &__key, \ + (fn), (data)); \ + } while (0) +#else +#define init_timer(timer)\ + init_timer_key((timer), NULL, NULL) +#define init_timer_deferrable(timer)\ + init_timer_deferrable_key((timer), NULL, NULL) +#define init_timer_on_stack(timer)\ + init_timer_on_stack_key((timer), NULL, NULL) +#define setup_timer(timer, fn, data)\ + setup_timer_key((timer), NULL, NULL, (fn), (data)) +#define setup_timer_on_stack(timer, fn, data)\ + setup_timer_on_stack_key((timer), NULL, NULL, (fn), (data)) +#endif #ifdef CONFIG_DEBUG_OBJECTS_TIMERS -extern void init_timer_on_stack(struct timer_list *timer); +extern void init_timer_on_stack_key(struct timer_list *timer, + const char *name, + struct lock_class_key *key); extern void destroy_timer_on_stack(struct timer_list *timer); #else static inline void destroy_timer_on_stack(struct timer_list *timer) { } -static inline void init_timer_on_stack(struct timer_list *timer) +static inline void init_timer_on_stack_key(struct timer_list *timer, + const char *name, + struct lock_class_key *key) { - init_timer(timer); + init_timer_key(timer, name, key); } #endif -static inline void setup_timer(struct timer_list * timer, +static inline void setup_timer_key(struct timer_list * timer, + const char *name, + struct lock_class_key *key, void (*function)(unsigned long), unsigned long data) { timer->function = function; timer->data = data; - init_timer(timer); + init_timer_key(timer, name, key); } -static inline void setup_timer_on_stack(struct timer_list *timer, +static inline void setup_timer_on_stack_key(struct timer_list *timer, + const char *name, + struct lock_class_key *key, void (*function)(unsigned long), unsigned long data) { timer->function = function; timer->data = data; - init_timer_on_stack(timer); + init_timer_on_stack_key(timer, name, key); } /** -- cgit v1.2.2 From 74019224ac34b044b44a31dd89a54e3477db4896 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 18 Feb 2009 12:23:29 +0100 Subject: timers: add mod_timer_pending() Impact: new timer API Based on an idea from Martin Josefsson with the help of Patrick McHardy and Stephen Hemminger: introduce the mod_timer_pending() API which is a mod_timer() offspring that is an invariant on already removed timers. (regular mod_timer() re-activates non-pending timers.) This is useful for the networking code in that it can allow unserialized mod_timer_pending() timer-forwarding calls, but a single del_timer*() will stop the timer from being reactivated again. Also while at it: - optimize the regular mod_timer() path some more, the timer-stat and a debug check was needlessly duplicated in __mod_timer(). - make the exports come straight after the function, as most other exports in timer.c already did. - eliminate __mod_timer() as an external API, change the users to mod_timer(). The regular mod_timer() code path is not impacted significantly, due to inlining optimizations and due to the simplifications. Based-on-patch-from: Stephen Hemminger Acked-by: Stephen Hemminger Cc: "David S. Miller" Cc: Patrick McHardy Cc: netdev@vger.kernel.org Cc: Oleg Nesterov Cc: Andrew Morton Signed-off-by: Ingo Molnar --- include/linux/timer.h | 22 ++-------------------- 1 file changed, 2 insertions(+), 20 deletions(-) (limited to 'include/linux/timer.h') diff --git a/include/linux/timer.h b/include/linux/timer.h index daf9685b861c..e2d662e3416e 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -86,8 +86,8 @@ static inline int timer_pending(const struct timer_list * timer) extern void add_timer_on(struct timer_list *timer, int cpu); extern int del_timer(struct timer_list * timer); -extern int __mod_timer(struct timer_list *timer, unsigned long expires); extern int mod_timer(struct timer_list *timer, unsigned long expires); +extern int mod_timer_pending(struct timer_list *timer, unsigned long expires); /* * The jiffies value which is added to now, when there is no timer @@ -146,25 +146,7 @@ static inline void timer_stats_timer_clear_start_info(struct timer_list *timer) } #endif -/** - * add_timer - start a timer - * @timer: the timer to be added - * - * The kernel will do a ->function(->data) callback from the - * timer interrupt at the ->expires point in the future. The - * current time is 'jiffies'. - * - * The timer's ->expires, ->function (and if the handler uses it, ->data) - * fields must be set prior calling this function. - * - * Timers with an ->expires field in the past will be executed in the next - * timer tick. - */ -static inline void add_timer(struct timer_list *timer) -{ - BUG_ON(timer_pending(timer)); - __mod_timer(timer, timer->expires); -} +extern void add_timer(struct timer_list *timer); #ifdef CONFIG_SMP extern int try_to_del_timer_sync(struct timer_list *timer); -- cgit v1.2.2