n
functionality.

No functional change.

Co-developed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Link: https://lore.kernel.org/all/20220407161745.7d6754b3@gandalf.local.home
Link: https://lore.kernel.org/all/20221110064101.429013735@goodmis.org
Link: https://lore.kernel.org/r/20221123201625.195147423@linutronix.de
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
 kernel/time/timer.c | 143 ++++++++++++++++++++++++++++----------------
 1 file changed, 92 insertions(+), 51 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 3b6624cd9507..0b76a2ab42e3 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1298,20 +1298,14 @@ void add_timer_on(struct timer_list *timer, int cpu)
 EXPORT_SYMBOL_GPL(add_timer_on);
 
 /**
- * timer_delete - Deactivate a timer
+ * __timer_delete - Internal function: Deactivate a timer
  * @timer:	The timer to be deactivated
  *
- * The function only deactivates a pending timer, but contrary to
- * timer_delete_sync() it does not take into account whether the timer's
- * callback function is concurrently executed on a different CPU or not.
- * It neither prevents rearming of the timer. If @timer can be rearmed
- * concurrently then the return value of this function is meaningless.
- *
  * Return:
  * * %0 - The timer was not pending
  * * %1 - The timer was pending and deactivated
  */
-int timer_delete(struct timer_list *timer)
+static int __timer_delete(struct timer_list *timer)
 {
 	struct timer_base *base;
 	unsigned long flags;
@@ -1327,25 +1321,37 @@ int timer_delete(struct timer_list *timer)
 
 	return ret;
 }
-EXPORT_SYMBOL(timer_delete);
 
 /**
- * try_to_del_timer_sync - Try to deactivate a timer
- * @timer:	Timer to deactivate
+ * timer_delete - Deactivate a timer
+ * @timer:	The timer to be deactivated
  *
- * This function tries to deactivate a timer. On success the timer is not
- * queued and the timer callback function is not running on any CPU.
+ * The function only deactivates a pending timer, but contrary to
+ * timer_delete_sync() it does not take into account whether the timer's
+ * callback function is concurrently executed on a different CPU or not.
+ * It neither prevents rearming of the timer.  If @timer can be rearmed
+ * concurrently then the return value of this function is meaningless.
  *
- * This function does not guarantee that the timer cannot be rearmed right
- * after dropping the base lock. That needs to be prevented by the calling
- * code if necessary.
+ * Return:
+ * * %0 - The timer was not pending
+ * * %1 - The timer was pending and deactivated
+ */
+int timer_delete(struct timer_list *timer)
+{
+	return __timer_delete(timer);
+}
+EXPORT_SYMBOL(timer_delete);
+
+/**
+ * __try_to_del_timer_sync - Internal function: Try to deactivate a timer
+ * @timer:	Timer to deactivate
  *
  * Return:
  * * %0  - The timer was not pending
  * * %1  - The timer was pending and deactivated
  * * %-1 - The timer callback function is running on a different CPU
  */
-int try_to_del_timer_sync(struct timer_list *timer)
+static int __try_to_del_timer_sync(struct timer_list *timer)
 {
 	struct timer_base *base;
 	unsigned long flags;
@@ -1362,6 +1368,27 @@ int try_to_del_timer_sync(struct timer_list *timer)
 
 	return ret;
 }
+
+/**
+ * try_to_del_timer_sync - Try to deactivate a timer
+ * @timer:	Timer to deactivate
+ *
+ * This function tries to deactivate a timer. On success the timer is not
+ * queued and the timer callback function is not running on any CPU.
+ *
+ * This function does not guarantee that the timer cannot be rearmed right
+ * after dropping the base lock. That needs to be prevented by the calling
+ * code if necessary.
+ *
+ * Return:
+ * * %0  - The timer was not pending
+ * * %1  - The timer was pending and deactivated
+ * * %-1 - The timer callback function is running on a different CPU
+ */
+int try_to_del_timer_sync(struct timer_list *timer)
+{
+	return __try_to_del_timer_sync(timer);
+}
 EXPORT_SYMBOL(try_to_del_timer_sync);
 
 #ifdef CONFIG_PREEMPT_RT
@@ -1438,45 +1465,15 @@ static inline void del_timer_wait_running(struct timer_list *timer) { }
 #endif
 
 /**
- * timer_delete_sync - Deactivate a timer and wait for the handler to finish.
+ * __timer_delete_sync - Internal function: Deactivate a timer and wait
+ *			 for the handler to finish.
  * @timer:	The timer to be deactivated
  *
- * Synchronization rules: Callers must prevent restarting of the timer,
- * otherwise this function is meaningless. It must not be called from
- * interrupt contexts unless the timer is an irqsafe one. The caller must
- * not hold locks which would prevent completion of the timer's callback
- * function. 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.
- *
- * For !irqsafe timers, the caller must not hold locks that are held in
- * interrupt context. Even if the lock has nothing to do with the timer in
- * question.  Here's why::
- *
- *    CPU0                             CPU1
- *    ----                             ----
- *                                     <SOFTIRQ>
- *                                       call_timer_fn();
- *                                       base->running_timer = mytimer;
- *    spin_lock_irq(somelock);
- *                                     <IRQ>
- *                                        spin_lock(somelock);
- *    timer_delete_sync(mytimer);
- *    while (base->running_timer == mytimer);
- *
- * Now timer_delete_sync() will never return and never release somelock.
- * The interrupt on the other CPU is waiting to grab somelock but it has
- * interrupted the softirq that CPU0 is waiting to finish.
- *
- * This function cannot guarantee that the timer is not rearmed again by
- * some concurrent or preempting code, right after it dropped the base
- * lock. If there is the possibility of a concurrent rearm then the return
- * value of the function is meaningless.
- *
  * Return:
  * * %0	- The timer was not pending
  * * %1	- The timer was pending and deactivated
  */
-int timer_delete_sync(struct timer_list *timer)
+static int __timer_delete_sync(struct timer_list *timer)
 {
 	int ret;
 
@@ -1506,7 +1503,7 @@ int timer_delete_sync(struct timer_list *timer)
 		lockdep_assert_preemption_enabled();
 
 	do {
-		ret = try_to_del_timer_sync(timer);
+		ret = __try_to_del_timer_sync(timer);
 
 		if (unlikely(ret < 0)) {
 			del_timer_wait_running(timer);
@@ -1516,6 +1513,50 @@ int timer_delete_sync(struct timer_list *timer)
 
 	return ret;
 }
+
+/**
+ * timer_delete_sync - Deactivate a timer and wait for the handler to finish.
+ * @timer:	The timer to be deactivated
+ *
+ * Synchronization rules: Callers must prevent restarting of the timer,
+ * otherwise this function is meaningless. It must not be called from
+ * interrupt contexts unless the timer is an irqsafe one. The caller must
+ * not hold locks which would prevent completion of the timer's callback
+ * function. 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.
+ *
+ * For !irqsafe timers, the caller must not hold locks that are held in
+ * interrupt context. Even if the lock has nothing to do with the timer in
+ * question.  Here's why::
+ *
+ *    CPU0                             CPU1
+ *    ----                             ----
+ *                                     <SOFTIRQ>
+ *                                       call_timer_fn();
+ *                                       base->running_timer = mytimer;
+ *    spin_lock_irq(somelock);
+ *                                     <IRQ>
+ *                                        spin_lock(somelock);
+ *    timer_delete_sync(mytimer);
+ *    while (base->running_timer == mytimer);
+ *
+ * Now timer_delete_sync() will never return and never release somelock.
+ * The interrupt on the other CPU is waiting to grab somelock but it has
+ * interrupted the softirq that CPU0 is waiting to finish.
+ *
+ * This function cannot guarantee that the timer is not rearmed again by
+ * some concurrent or preempting code, right after it dropped the base
+ * lock. If there is the possibility of a concurrent rearm then the return
+ * value of the function is meaningless.
+ *
+ * Return:
+ * * %0	- The timer was not pending
+ * * %1	- The timer was pending and deactivated
+ */
+int timer_delete_sync(struct timer_list *timer)
+{
+	return __timer_delete_sync(timer);
+}
 EXPORT_SYMBOL(timer_delete_sync);
 
 static void call_timer_fn(struct timer_list *timer,
--[PATCH 6.1.y 08/12] timers: Split [try_to_]del_timer[_sync]() to prepare for shutdown modeJeongjun Park <aha310510@gmail.com> undefinedstable@vger.kernel.org undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefined undefinedž)*
