[PATCHv5 06/37] alarmtimer: Provide get_timespec() callback

[Dmitry Safonov <dima@arista.com>]

From: Andrei Vagin <avagin@gmail.com>

The upcoming support for time namespaces requires to have access to:
  - The time in a task's time namespace for sys_clock_gettime()
  - The time in the root name space for common_timer_get()

Wire up alarm bases with get_timespec().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Co-developed-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/posix-timers.h | 3 +++
 kernel/time/alarmtimer.c     | 8 ++++++--
 kernel/time/posix-timers.c   | 4 ++--
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b20798fc5191..fe13ab265213 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -127,4 +127,7 @@ void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
 
 void posixtimer_rearm(struct kernel_siginfo *info);
+
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp);
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp);
 #endif
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index 37254eb64459..d9e6baa9976a 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -37,12 +37,15 @@
  * @lock:		Lock for syncrhonized access to the base
  * @timerqueue:		Timerqueue head managing the list of events
  * @get_ktime:		Function to read the time correlating to the base
+ * @get_timespec:	Function to read the namespace time correlating to the base
  * @base_clockid:	clockid for the base
  */
 static struct alarm_base {
 	spinlock_t		lock;
 	struct timerqueue_head	timerqueue;
 	ktime_t			(*get_ktime)(void);
+	int			(*get_timespec)(const clockid_t which_clock,
+						struct timespec64 *tp);
 	clockid_t		base_clockid;
 } alarm_bases[ALARM_NUMTYPE];
 
@@ -657,8 +660,7 @@ static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp
 	if (!alarmtimer_get_rtcdev())
 		return -EINVAL;
 
-	*tp = ktime_to_timespec64(base->get_ktime());
-	return 0;
+	return base->get_timespec(base->base_clockid, tp);
 }
 
 /**
@@ -869,8 +871,10 @@ static int __init alarmtimer_init(void)
 	/* Initialize alarm bases */
 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
 	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
+	alarm_bases[ALARM_REALTIME].get_timespec = posix_get_timespec,
 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
 	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
+	alarm_bases[ALARM_BOOTTIME].get_timespec = posix_get_boottime_timespec;
 	for (i = 0; i < ALARM_NUMTYPE; i++) {
 		timerqueue_init_head(&alarm_bases[i].timerqueue);
 		spin_lock_init(&alarm_bases[i].lock);
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index a71e43178a7d..a600b8b3e9bf 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -188,7 +188,7 @@ static int posix_clock_realtime_adj(const clockid_t which_clock,
 /*
  * Get monotonic time for posix timers
  */
-static int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
+int posix_get_timespec(clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_ts64(tp);
 	return 0;
@@ -223,7 +223,7 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
 	return 0;
 }
 
-static int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
+int posix_get_boottime_timespec(const clockid_t which_clock, struct timespec64 *tp)
 {
 	ktime_get_boottime_ts64(tp);
 	return 0;
-- 
2.22.0