timers: Make 'pinned' a timer property

We want to move the timer migration logic from a 'push' to a 'pull' model.

Under the current 'push' model pinned timers are handled via
a runtime API variant: mod_timer_pinned().

The 'pull' model requires us to store the pinned attribute of a timer
in the timer_list structure itself, as a new TIMER_PINNED bit in
timer->flags.

This flag must be set at initialization time and the timer APIs
recognize the flag.

This patch:

 - Implements the new flag and associated new-style initialization
   methods

 - makes mod_timer() recognize new-style pinned timers,

 - and adds some migration helper facility to allow
   step by step conversion of old-style to new-style
   pinned timers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160704094341.049338558@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/timer.h b/include/linux/timer.h
index 20ac746..046d6cf 100644 (file)
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -62,7 +62,8 @@ struct timer_list {
 #define TIMER_MIGRATING                0x00080000
 #define TIMER_BASEMASK         (TIMER_CPUMASK | TIMER_MIGRATING)
 #define TIMER_DEFERRABLE       0x00100000
-#define TIMER_IRQSAFE          0x00200000
+#define TIMER_PINNED           0x00200000
+#define TIMER_IRQSAFE          0x00400000
 
 #define __TIMER_INITIALIZER(_function, _expires, _data, _flags) { \
                .entry = { .next = TIMER_ENTRY_STATIC },        \
@@ -78,9 +79,15 @@ struct timer_list {
 #define TIMER_INITIALIZER(_function, _expires, _data)          \
        __TIMER_INITIALIZER((_function), (_expires), (_data), 0)
 
+#define TIMER_PINNED_INITIALIZER(_function, _expires, _data)   \
+       __TIMER_INITIALIZER((_function), (_expires), (_data), TIMER_PINNED)
+
 #define TIMER_DEFERRED_INITIALIZER(_function, _expires, _data) \
        __TIMER_INITIALIZER((_function), (_expires), (_data), TIMER_DEFERRABLE)
 
+#define TIMER_PINNED_DEFERRED_INITIALIZER(_function, _expires, _data)  \
+       __TIMER_INITIALIZER((_function), (_expires), (_data), TIMER_DEFERRABLE | TIMER_PINNED)
+
 #define DEFINE_TIMER(_name, _function, _expires, _data)                \
        struct timer_list _name =                               \
                TIMER_INITIALIZER(_function, _expires, _data)
@@ -124,8 +131,12 @@ static inline void init_timer_on_stack_key(struct timer_list *timer,
 
 #define init_timer(timer)                                              \
        __init_timer((timer), 0)
+#define init_timer_pinned(timer)                                       \
+       __init_timer((timer), TIMER_PINNED)
 #define init_timer_deferrable(timer)                                   \
        __init_timer((timer), TIMER_DEFERRABLE)
+#define init_timer_pinned_deferrable(timer)                            \
+       __init_timer((timer), TIMER_DEFERRABLE | TIMER_PINNED)
 #define init_timer_on_stack(timer)                                     \
        __init_timer_on_stack((timer), 0)
 
@@ -145,12 +156,20 @@ static inline void init_timer_on_stack_key(struct timer_list *timer,
 
 #define setup_timer(timer, fn, data)                                   \
        __setup_timer((timer), (fn), (data), 0)
+#define setup_pinned_timer(timer, fn, data)                            \
+       __setup_timer((timer), (fn), (data), TIMER_PINNED)
 #define setup_deferrable_timer(timer, fn, data)                                \
        __setup_timer((timer), (fn), (data), TIMER_DEFERRABLE)
+#define setup_pinned_deferrable_timer(timer, fn, data)                 \
+       __setup_timer((timer), (fn), (data), TIMER_DEFERRABLE | TIMER_PINNED)
 #define setup_timer_on_stack(timer, fn, data)                          \
        __setup_timer_on_stack((timer), (fn), (data), 0)
+#define setup_pinned_timer_on_stack(timer, fn, data)                   \
+       __setup_timer_on_stack((timer), (fn), (data), TIMER_PINNED)
 #define setup_deferrable_timer_on_stack(timer, fn, data)               \
        __setup_timer_on_stack((timer), (fn), (data), TIMER_DEFERRABLE)
+#define setup_pinned_deferrable_timer_on_stack(timer, fn, data)                \
+       __setup_timer_on_stack((timer), (fn), (data), TIMER_DEFERRABLE | TIMER_PINNED)
 
 /**
  * timer_pending - is a timer pending?
@@ -175,8 +194,8 @@ extern int mod_timer_pinned(struct timer_list *timer, unsigned long expires);
 
 extern void set_timer_slack(struct timer_list *time, int slack_hz);
 
-#define TIMER_NOT_PINNED       0
-#define TIMER_PINNED           1
+#define MOD_TIMER_NOT_PINNED   0
+#define MOD_TIMER_PINNED       1
 /*
  * The jiffies value which is added to now, when there is no timer
  * in the timer wheel:

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 3a95f97..693f6d1 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -782,7 +782,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
 
        debug_activate(timer, expires);
 
-       new_base = get_target_base(base, pinned);
+       new_base = get_target_base(base, pinned || timer->flags & TIMER_PINNED);
 
        if (base != new_base) {
                /*
@@ -825,7 +825,7 @@ out_unlock:
  */
 int mod_timer_pending(struct timer_list *timer, unsigned long expires)
 {
-       return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
+       return __mod_timer(timer, expires, true, MOD_TIMER_NOT_PINNED);
 }
 EXPORT_SYMBOL(mod_timer_pending);
 
@@ -900,7 +900,7 @@ int mod_timer(struct timer_list *timer, unsigned long expires)
        if (timer_pending(timer) && timer->expires == expires)
                return 1;
 
-       return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
+       return __mod_timer(timer, expires, false, MOD_TIMER_NOT_PINNED);
 }
 EXPORT_SYMBOL(mod_timer);
 
@@ -928,7 +928,7 @@ int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
        if (timer->expires == expires && timer_pending(timer))
                return 1;
 
-       return __mod_timer(timer, expires, false, TIMER_PINNED);
+       return __mod_timer(timer, expires, false, MOD_TIMER_PINNED);
 }
 EXPORT_SYMBOL(mod_timer_pinned);
 
@@ -1512,7 +1512,7 @@ signed long __sched schedule_timeout(signed long timeout)
        expire = timeout + jiffies;
 
        setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
-       __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
+       __mod_timer(&timer, expire, false, MOD_TIMER_NOT_PINNED);
        schedule();
        del_singleshot_timer_sync(&timer);