Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer changes from Ingo Molnar:
 "Timer enhancements, generalizations and cleanups from Tejun Heo, in
  preparation for workqueue facility enhancements."

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timer: Implement TIMER_IRQSAFE
  timer: Clean up timer initializers
  timer: Relocate declarations of init_timer_on_stack_key()
  timer: Generalize timer->base flags handling

2 files changed, 114 insertions, 159 deletions

diff --git a/include/linux/timer.h b/include/linux/timer.h
index 6abd9138beda..8c5a197e1587 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 8c5e7b908c68..d5de1b2292aa 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;
@@ -1791,9 +1777,13 @@ 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);