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Message-ID: <20121001131810.GA22625@gmail.com>
Date: Mon, 1 Oct 2012 15:18:10 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] timer changes for v3.7
Linus,
Please pull the latest timers-core-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-core-for-linus
HEAD: c5f66e99b7cb091e3d51ae8e8156892e8feb7fa3 timer: Implement TIMER_IRQSAFE
timer enhancements, generalizations and cleanups from Tejun Heo,
in preparation for workqueue facility enhancements.
Thanks,
Ingo
------------------>
Tejun Heo (4):
timer: Generalize timer->base flags handling
timer: Relocate declarations of init_timer_on_stack_key()
timer: Clean up timer initializers
timer: Implement TIMER_IRQSAFE
include/linux/timer.h | 165 ++++++++++++++++++++------------------------------
kernel/timer.c | 108 +++++++++++++++------------------
2 files changed, 114 insertions(+), 159 deletions(-)
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 6abd913..8c5a197 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -49,147 +49,112 @@ extern struct tvec_base boot_tvec_bases;
#endif
/*
- * Note that all tvec_bases are 2 byte aligned and lower bit of
- * base in timer_list is guaranteed to be zero. Use the LSB to
- * indicate whether the timer is deferrable.
+ * Note that all tvec_bases are at least 4 byte aligned and lower two bits
+ * of base in timer_list is guaranteed to be zero. Use them for flags.
*
* A deferrable timer will work normally when the system is busy, but
* will not cause a CPU to come out of idle just to service it; instead,
* the timer will be serviced when the CPU eventually wakes up with a
* subsequent non-deferrable timer.
+ *
+ * An irqsafe timer is executed with IRQ disabled and it's safe to wait for
+ * the completion of the running instance from IRQ handlers, for example,
+ * by calling del_timer_sync().
+ *
+ * Note: The irq disabled callback execution is a special case for
+ * workqueue locking issues. It's not meant for executing random crap
+ * with interrupts disabled. Abuse is monitored!
*/
-#define TBASE_DEFERRABLE_FLAG (0x1)
+#define TIMER_DEFERRABLE 0x1LU
+#define TIMER_IRQSAFE 0x2LU
-#define TIMER_INITIALIZER(_function, _expires, _data) { \
+#define TIMER_FLAG_MASK 0x3LU
+
+#define __TIMER_INITIALIZER(_function, _expires, _data, _flags) { \
.entry = { .prev = TIMER_ENTRY_STATIC }, \
.function = (_function), \
.expires = (_expires), \
.data = (_data), \
- .base = &boot_tvec_bases, \
+ .base = (void *)((unsigned long)&boot_tvec_bases + (_flags)), \
.slack = -1, \
__TIMER_LOCKDEP_MAP_INITIALIZER( \
__FILE__ ":" __stringify(__LINE__)) \
}
-#define TBASE_MAKE_DEFERRED(ptr) ((struct tvec_base *) \
- ((unsigned char *)(ptr) + TBASE_DEFERRABLE_FLAG))
+#define TIMER_INITIALIZER(_function, _expires, _data) \
+ __TIMER_INITIALIZER((_function), (_expires), (_data), 0)
-#define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) {\
- .entry = { .prev = TIMER_ENTRY_STATIC }, \
- .function = (_function), \
- .expires = (_expires), \
- .data = (_data), \
- .base = TBASE_MAKE_DEFERRED(&boot_tvec_bases), \
- __TIMER_LOCKDEP_MAP_INITIALIZER( \
- __FILE__ ":" __stringify(__LINE__)) \
- }
+#define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) \
+ __TIMER_INITIALIZER((_function), (_expires), (_data), TIMER_DEFERRABLE)
#define DEFINE_TIMER(_name, _function, _expires, _data) \
struct timer_list _name = \
TIMER_INITIALIZER(_function, _expires, _data)
-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);
+void init_timer_key(struct timer_list *timer, unsigned int flags,
+ const char *name, struct lock_class_key *key);
+
+#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
+extern void init_timer_on_stack_key(struct timer_list *timer,
+ unsigned int flags, 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_key(struct timer_list *timer,
+ unsigned int flags, const char *name,
+ struct lock_class_key *key)
+{
+ init_timer_key(timer, flags, name, key);
+}
+#endif
#ifdef CONFIG_LOCKDEP
-#define init_timer(timer) \
+#define __init_timer(_timer, _flags) \
do { \
static struct lock_class_key __key; \
- init_timer_key((timer), #timer, &__key); \
+ init_timer_key((_timer), (_flags), #_timer, &__key); \
} while (0)
-#define init_timer_deferrable(timer) \
+#define __init_timer_on_stack(_timer, _flags) \
do { \
static struct lock_class_key __key; \
- init_timer_deferrable_key((timer), #timer, &__key); \
+ init_timer_on_stack_key((_timer), (_flags), #_timer, &__key); \
} while (0)
+#else
+#define __init_timer(_timer, _flags) \
+ init_timer_key((_timer), (_flags), NULL, NULL)
+#define __init_timer_on_stack(_timer, _flags) \
+ init_timer_on_stack_key((_timer), (_flags), NULL, NULL)
+#endif
+#define init_timer(timer) \
+ __init_timer((timer), 0)
+#define init_timer_deferrable(timer) \
+ __init_timer((timer), TIMER_DEFERRABLE)
#define init_timer_on_stack(timer) \
+ __init_timer_on_stack((timer), 0)
+
+#define __setup_timer(_timer, _fn, _data, _flags) \
do { \
- static struct lock_class_key __key; \
- init_timer_on_stack_key((timer), #timer, &__key); \
+ __init_timer((_timer), (_flags)); \
+ (_timer)->function = (_fn); \
+ (_timer)->data = (_data); \
} while (0)
-#define setup_timer(timer, fn, data) \
+#define __setup_timer_on_stack(_timer, _fn, _data, _flags) \
do { \
- static struct lock_class_key __key; \
- setup_timer_key((timer), #timer, &__key, (fn), (data));\
+ __init_timer_on_stack((_timer), (_flags)); \
+ (_timer)->function = (_fn); \
+ (_timer)->data = (_data); \
} while (0)
+#define setup_timer(timer, fn, data) \
+ __setup_timer((timer), (fn), (data), 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)
+ __setup_timer_on_stack((timer), (fn), (data), 0)
#define setup_deferrable_timer_on_stack(timer, fn, data) \
- do { \
- static struct lock_class_key __key; \
- setup_deferrable_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))
-#define setup_deferrable_timer_on_stack(timer, fn, data)\
- setup_deferrable_timer_on_stack_key((timer), NULL, NULL, (fn), (data))
-#endif
-
-#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
-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_key(struct timer_list *timer,
- const char *name,
- struct lock_class_key *key)
-{
- init_timer_key(timer, name, key);
-}
-#endif
-
-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_key(timer, name, key);
-}
-
-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_key(timer, name, key);
-}
-
-extern void setup_deferrable_timer_on_stack_key(struct timer_list *timer,
- const char *name,
- struct lock_class_key *key,
- void (*function)(unsigned long),
- unsigned long data);
+ __setup_timer_on_stack((timer), (fn), (data), TIMER_DEFERRABLE)
/**
* timer_pending - is a timer pending?
diff --git a/kernel/timer.c b/kernel/timer.c
index a61c093..706fe4c 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -92,24 +92,25 @@ static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
/* Functions below help us manage 'deferrable' flag */
static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
{
- return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
+ return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE);
}
-static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
+static inline unsigned int tbase_get_irqsafe(struct tvec_base *base)
{
- return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));
+ return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE);
}
-static inline void timer_set_deferrable(struct timer_list *timer)
+static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
{
- timer->base = TBASE_MAKE_DEFERRED(timer->base);
+ return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK));
}
static inline void
timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
{
- timer->base = (struct tvec_base *)((unsigned long)(new_base) |
- tbase_get_deferrable(timer->base));
+ unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK;
+
+ timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags);
}
static unsigned long round_jiffies_common(unsigned long j, int cpu,
@@ -563,16 +564,14 @@ 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);
+static void do_init_timer(struct timer_list *timer, unsigned int flags,
+ 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)
+void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags,
+ const char *name, struct lock_class_key *key)
{
debug_object_init_on_stack(timer, &timer_debug_descr);
- __init_timer(timer, name, key);
+ do_init_timer(timer, flags, name, key);
}
EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
@@ -613,12 +612,13 @@ 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)
+static void do_init_timer(struct timer_list *timer, unsigned int flags,
+ const char *name, struct lock_class_key *key)
{
+ struct tvec_base *base = __raw_get_cpu_var(tvec_bases);
+
timer->entry.next = NULL;
- timer->base = __raw_get_cpu_var(tvec_bases);
+ timer->base = (void *)((unsigned long)base | flags);
timer->slack = -1;
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
@@ -628,22 +628,10 @@ static void __init_timer(struct timer_list *timer,
lockdep_init_map(&timer->lockdep_map, name, key, 0);
}
-void setup_deferrable_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_key(timer, name, key);
- timer_set_deferrable(timer);
-}
-EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key);
-
/**
* init_timer_key - initialize a timer
* @timer: the timer to be initialized
+ * @flags: timer flags
* @name: name of the timer
* @key: lockdep class key of the fake lock used for tracking timer
* sync lock dependencies
@@ -651,24 +639,14 @@ EXPORT_SYMBOL_GPL(setup_deferrable_timer_on_stack_key);
* init_timer_key() must be done to a timer prior calling *any* of the
* other timer functions.
*/
-void init_timer_key(struct timer_list *timer,
- const char *name,
- struct lock_class_key *key)
+void init_timer_key(struct timer_list *timer, unsigned int flags,
+ const char *name, struct lock_class_key *key)
{
debug_init(timer);
- __init_timer(timer, name, key);
+ do_init_timer(timer, flags, name, key);
}
EXPORT_SYMBOL(init_timer_key);
-void init_timer_deferrable_key(struct timer_list *timer,
- const char *name,
- struct lock_class_key *key)
-{
- init_timer_key(timer, name, key);
- timer_set_deferrable(timer);
-}
-EXPORT_SYMBOL(init_timer_deferrable_key);
-
static inline void detach_timer(struct timer_list *timer, bool clear_pending)
{
struct list_head *entry = &timer->entry;
@@ -686,7 +664,7 @@ detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
{
detach_timer(timer, true);
if (!tbase_get_deferrable(timer->base))
- timer->base->active_timers--;
+ base->active_timers--;
}
static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
@@ -697,7 +675,7 @@ static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
detach_timer(timer, clear_pending);
if (!tbase_get_deferrable(timer->base)) {
- timer->base->active_timers--;
+ base->active_timers--;
if (timer->expires == base->next_timer)
base->next_timer = base->timer_jiffies;
}
@@ -1029,14 +1007,14 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
*
* Synchronization rules: Callers must prevent restarting of the timer,
* otherwise this function is meaningless. It must not be called from
- * interrupt contexts. The caller must not hold locks which would prevent
- * completion of the timer's handler. The timer's handler must not call
- * add_timer_on(). Upon exit the timer is not queued and the handler is
- * not running on any CPU.
+ * interrupt contexts unless the timer is an irqsafe one. The caller must
+ * not hold locks which would prevent completion of the timer's
+ * handler. The timer's handler must not call add_timer_on(). Upon exit the
+ * timer is not queued and the handler is not running on any CPU.
*
- * Note: You must not hold locks that are held in interrupt context
- * while calling this function. Even if the lock has nothing to do
- * with the timer in question. Here's why:
+ * Note: For !irqsafe timers, you must not hold locks that are held in
+ * interrupt context while calling this function. Even if the lock has
+ * nothing to do with the timer in question. Here's why:
*
* CPU0 CPU1
* ---- ----
@@ -1073,7 +1051,7 @@ int del_timer_sync(struct timer_list *timer)
* don't use it in hardirq context, because it
* could lead to deadlock.
*/
- WARN_ON(in_irq());
+ WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base));
for (;;) {
int ret = try_to_del_timer_sync(timer);
if (ret >= 0)
@@ -1180,19 +1158,27 @@ static inline void __run_timers(struct tvec_base *base)
while (!list_empty(head)) {
void (*fn)(unsigned long);
unsigned long data;
+ bool irqsafe;
timer = list_first_entry(head, struct timer_list,entry);
fn = timer->function;
data = timer->data;
+ irqsafe = tbase_get_irqsafe(timer->base);
timer_stats_account_timer(timer);
base->running_timer = timer;
detach_expired_timer(timer, base);
- spin_unlock_irq(&base->lock);
- call_timer_fn(timer, fn, data);
- spin_lock_irq(&base->lock);
+ if (irqsafe) {
+ spin_unlock(&base->lock);
+ call_timer_fn(timer, fn, data);
+ spin_lock(&base->lock);
+ } else {
+ spin_unlock_irq(&base->lock);
+ call_timer_fn(timer, fn, data);
+ spin_lock_irq(&base->lock);
+ }
}
}
base->running_timer = NULL;
@@ -1800,9 +1786,13 @@ static struct notifier_block __cpuinitdata timers_nb = {
void __init init_timers(void)
{
- int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
- (void *)(long)smp_processor_id());
+ int err;
+
+ /* ensure there are enough low bits for flags in timer->base pointer */
+ BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK);
+ err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
+ (void *)(long)smp_processor_id());
init_timer_stats();
BUG_ON(err != NOTIFY_OK);
--
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