timers: Track total number of timers in list

Currently, the tvec_base structure's ->active_timers field tracks only
the non-deferrable timers, which means that even if ->active_timers is
zero, there might well be deferrable timers in the list.  This commit
therefore adds an ->all_timers field to track all the timers, whether
deferrable or not.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Mike Galbraith <bitbucket@online.de>

diff --git a/kernel/timer.c b/kernel/timer.c
index accfd24..fdc4383 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -81,6 +81,7 @@ struct tvec_base {
        unsigned long timer_jiffies;
        unsigned long next_timer;
        unsigned long active_timers;
+       unsigned long all_timers;
        struct tvec_root tv1;
        struct tvec tv2;
        struct tvec tv3;
@@ -392,6 +393,7 @@ static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
                        base->next_timer = timer->expires;
                base->active_timers++;
        }
+       base->all_timers++;
 }
 
 #ifdef CONFIG_TIMER_STATS
@@ -671,6 +673,7 @@ detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
        detach_timer(timer, true);
        if (!tbase_get_deferrable(timer->base))
                base->active_timers--;
+       base->all_timers--;
 }
 
 static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
@@ -685,6 +688,7 @@ static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
                if (timer->expires == base->next_timer)
                        base->next_timer = base->timer_jiffies;
        }
+       base->all_timers--;
        return 1;
 }
 
@@ -1559,6 +1563,7 @@ static int init_timers_cpu(int cpu)
        base->timer_jiffies = jiffies;
        base->next_timer = base->timer_jiffies;
        base->active_timers = 0;
+       base->all_timers = 0;
        return 0;
 }