From: Frederic Weisbecker <frede...@kernel.org>

This commit adds a timer_curr_running() function that verifies that the
current code is running in the context of the specified timer's handler.

Cc: Josh Triplett <j...@joshtriplett.org>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Cc: Lai Jiangshan <jiangshan...@gmail.com>
Cc: Joel Fernandes <j...@joelfernandes.org>
Cc: Neeraj Upadhyay <neer...@codeaurora.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Tested-by: Boqun Feng <boqun.f...@gmail.com>
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
 include/linux/timer.h |  2 ++
 kernel/time/timer.c   | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/linux/timer.h b/include/linux/timer.h
index fda13c9..4118a97 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -192,6 +192,8 @@ extern int try_to_del_timer_sync(struct timer_list *timer);
 
 #define del_singleshot_timer_sync(t) del_timer_sync(t)
 
+extern bool timer_curr_running(struct timer_list *timer);
+
 extern void init_timers(void);
 struct hrtimer;
 extern enum hrtimer_restart it_real_fn(struct hrtimer *);
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 8dbc008..f9b2096 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1237,6 +1237,19 @@ int try_to_del_timer_sync(struct timer_list *timer)
 }
 EXPORT_SYMBOL(try_to_del_timer_sync);
 
+bool timer_curr_running(struct timer_list *timer)
+{
+       int i;
+
+       for (i = 0; i < NR_BASES; i++) {
+               struct timer_base *base = this_cpu_ptr(&timer_bases[i]);
+               if (base->running_timer == timer)
+                       return true;
+       }
+
+       return false;
+}
+
 #ifdef CONFIG_PREEMPT_RT
 static __init void timer_base_init_expiry_lock(struct timer_base *base)
 {
-- 
2.9.5

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