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Message-Id: <1233010786.4344.1.camel@johannes.local>
Date: Mon, 26 Jan 2009 23:59:46 +0100
From: Johannes Berg <johannes@...solutions.net>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Linux Kernel list <linux-kernel@...r.kernel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] 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.
Validated with this module, otherwise bootup was clean.
--->%---
#include <linux/module.h>
#include <linux/timer.h>
#include <linux/spinlock.h>
static struct timer_list t;
static spinlock_t l;
MODULE_LICENSE("GPL");
void fn(unsigned long dummy)
{
spin_lock_irq(&l);
spin_unlock_irq(&l);
printk(KERN_DEBUG "TEST\n");
}
static int i(void)
{
spin_lock_init(&l);
setup_timer(&t, fn, 0);
mod_timer(&t, jiffies + HZ);
return 0;
}
module_init(i);
static void e(void)
{
spin_lock_irq(&l);
del_timer_sync(&t);
spin_unlock_irq(&l);
}
module_exit(e);
---%<---
Signed-off-by: Johannes Berg <johannes@...solutions.net>
---
include/linux/timer.h | 93 +++++++++++++++++++++++++++++++++++++++++---------
kernel/timer.c | 55 +++++++++++++++++++++++------
2 files changed, 121 insertions(+), 27 deletions(-)
--- wireless-testing.orig/include/linux/timer.h 2009-01-26 22:57:40.000000000 +0100
+++ wireless-testing/include/linux/timer.h 2009-01-26 22:57:52.000000000 +0100
@@ -21,52 +21,115 @@ 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;
-#define TIMER_INITIALIZER(_function, _expires, _data) { \
- .entry = { .prev = TIMER_ENTRY_STATIC }, \
- .function = (_function), \
- .expires = (_expires), \
- .data = (_data), \
- .base = &boot_tvec_bases, \
+#ifdef CONFIG_LOCKDEP
+#define __TIMER_LOCKDEP_MAP_INITIALIZER(fn, name) \
+ .lockdep_map = STATIC_LOCKDEP_MAP_INIT(name, fn),
+#else
+#define __TIMER_LOCKDEP_MAP_INITIALIZER(fn, name)
+#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((_function), #_function)\
}
#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);
}
/**
--- wireless-testing.orig/kernel/timer.c 2009-01-26 22:57:40.000000000 +0100
+++ wireless-testing/kernel/timer.c 2009-01-26 23:37:33.000000000 +0100
@@ -491,14 +491,18 @@ static inline void debug_timer_free(stru
debug_object_free(timer, &timer_debug_descr);
}
-static void __init_timer(struct timer_list *timer);
-
-void init_timer_on_stack(struct timer_list *timer)
+static void __init_timer(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key);
+
+void init_timer_on_stack_key(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key)
{
debug_object_init_on_stack(timer, &timer_debug_descr);
- __init_timer(timer);
+ __init_timer(timer, name, key);
}
-EXPORT_SYMBOL_GPL(init_timer_on_stack);
+EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
void destroy_timer_on_stack(struct timer_list *timer)
{
@@ -512,7 +516,9 @@ static inline void debug_timer_activate(
static inline void debug_timer_deactivate(struct timer_list *timer) { }
#endif
-static void __init_timer(struct timer_list *timer)
+static void __init_timer(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key)
{
timer->entry.next = NULL;
timer->base = __raw_get_cpu_var(tvec_bases);
@@ -521,6 +527,7 @@ static void __init_timer(struct timer_li
timer->start_pid = -1;
memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
+ lockdep_init_map(&timer->lockdep_map, name, key, 0);
}
/**
@@ -530,19 +537,23 @@ static void __init_timer(struct timer_li
* init_timer() must be done to a timer prior calling *any* of the
* other timer functions.
*/
-void init_timer(struct timer_list *timer)
+void init_timer_key(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key)
{
debug_timer_init(timer);
- __init_timer(timer);
+ __init_timer(timer, name, key);
}
-EXPORT_SYMBOL(init_timer);
+EXPORT_SYMBOL(init_timer_key);
-void init_timer_deferrable(struct timer_list *timer)
+void init_timer_deferrable_key(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key)
{
- init_timer(timer);
+ init_timer_key(timer, name, key);
timer_set_deferrable(timer);
}
-EXPORT_SYMBOL(init_timer_deferrable);
+EXPORT_SYMBOL(init_timer_deferrable_key);
static inline void detach_timer(struct timer_list *timer,
int clear_pending)
@@ -789,6 +800,15 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
*/
int del_timer_sync(struct timer_list *timer)
{
+#ifdef CONFIG_LOCKDEP
+ unsigned long flags;
+
+ local_irq_save(flags);
+ lock_map_acquire(&timer->lockdep_map);
+ lock_map_release(&timer->lockdep_map);
+ local_irq_restore(flags);
+#endif
+
for (;;) {
int ret = try_to_del_timer_sync(timer);
if (ret >= 0)
@@ -861,10 +881,21 @@ static inline void __run_timers(struct t
set_running_timer(base, timer);
detach_timer(timer, 1);
+
spin_unlock_irq(&base->lock);
{
int preempt_count = preempt_count();
+
+ /* Couple the lock chain with the lock chain at
+ * del_timer_sync by acquiring the lock_map around
+ * the fn() call here and in del_timer_sync.
+ */
+ lock_map_acquire(&timer->lockdep_map);
+
fn(data);
+
+ lock_map_release(&timer->lockdep_map);
+
if (preempt_count != preempt_count()) {
printk(KERN_ERR "huh, entered %p "
"with preempt_count %08x, exited"
--
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