From 4149c6a3ecd5526a6819443c8cfd17cc77bcbb3a Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Wed, 10 Jun 2020 22:30:32 +0000
Subject: [PATCH] Remove double-calls to tc_get_timecount() to warm
 timecounters.

It seems that second call does not add any useful state change for all
implemented timecounters.

Discussed with:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
---
 sys/dev/acpica/acpi.c         | 1 -
 sys/dev/acpica/acpi_timer.c   | 1 -
 sys/dev/xen/control/control.c | 1 -
 sys/kern/kern_tc.c            | 3 ---
 4 files changed, 6 deletions(-)

diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index 7fa4caf1d74..c3da5eb4cbb 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -3220,7 +3220,6 @@ acpi_resync_clock(struct acpi_softc *sc)
      * Warm up timecounter again and reset system clock.
      */
     (void)timecounter->tc_get_timecount(timecounter);
-    (void)timecounter->tc_get_timecount(timecounter);
     inittodr(time_second + sc->acpi_sleep_delay);
 }
 
diff --git a/sys/dev/acpica/acpi_timer.c b/sys/dev/acpica/acpi_timer.c
index 20ad87840c7..b15c39ac6bb 100644
--- a/sys/dev/acpica/acpi_timer.c
+++ b/sys/dev/acpica/acpi_timer.c
@@ -274,7 +274,6 @@ acpi_timer_resume_handler(struct timecounter *newtc)
 			    "restoring timecounter, %s -> %s\n",
 			    tc->tc_name, newtc->tc_name);
 		(void)newtc->tc_get_timecount(newtc);
-		(void)newtc->tc_get_timecount(newtc);
 		timecounter = newtc;
 	}
 }
diff --git a/sys/dev/xen/control/control.c b/sys/dev/xen/control/control.c
index f569b04dd95..6c71e67eda0 100644
--- a/sys/dev/xen/control/control.c
+++ b/sys/dev/xen/control/control.c
@@ -303,7 +303,6 @@ xctrl_suspend()
 	 * Warm up timecounter again and reset system clock.
 	 */
 	timecounter->tc_get_timecount(timecounter);
-	timecounter->tc_get_timecount(timecounter);
 	inittodr(time_second);
 
 #ifdef EARLY_AP_STARTUP
diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index 8d943d055aa..467e5cf8ee3 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -1206,7 +1206,6 @@ tc_init(struct timecounter *tc)
 	    tc->tc_frequency < timecounter->tc_frequency)
 		return;
 	(void)tc->tc_get_timecount(tc);
-	(void)tc->tc_get_timecount(tc);
 	timecounter = tc;
 }
 
@@ -1469,7 +1468,6 @@ sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
 
 		/* Warm up new timecounter. */
 		(void)newtc->tc_get_timecount(newtc);
-		(void)newtc->tc_get_timecount(newtc);
 
 		timecounter = newtc;
 
@@ -1963,7 +1961,6 @@ inittimecounter(void *dummy)
 
 	/* warm up new timecounter (again) and get rolling. */
 	(void)timecounter->tc_get_timecount(timecounter);
-	(void)timecounter->tc_get_timecount(timecounter);
 	mtx_lock_spin(&tc_setclock_mtx);
 	tc_windup(NULL);
 	mtx_unlock_spin(&tc_setclock_mtx);