[PATCH RT 32/36] timers: Track total number of timers in list

[Steven Rostedt]

3.12.38-rt53-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>

upstream commit: fff421580f512fc044cc7421fdff31a7a6997350

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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Tested-by: Mike Galbraith <bitbucket@xxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/timer.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/timer.c b/kernel/timer.c
index 3b79da2f9c67..1f1795734b70 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -84,6 +84,7 @@ 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;
@@ -395,6 +396,7 @@ 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
@@ -674,6 +676,7 @@ 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,
@@ -688,6 +691,7 @@ 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;
 }
 
@@ -1678,6 +1682,7 @@ 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;
 }
 
-- 
2.1.4


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