git: e6d31b4b70f0 - stable/13 - timecounter: Load the currently selected tc once in tc_windup()

The branch stable/13 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=e6d31b4b70f039f85420dd9ddf67e07651b72358

commit e6d31b4b70f039f85420dd9ddf67e07651b72358
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2021-10-29 18:29:22 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-07-19 13:59:14 +0000

    timecounter: Load the currently selected tc once in tc_windup()
    
    Reported by:    Sebastian Huber <sebastian.huber@embedded-brains.de>
    Reviewed by:    kib
    Sponsored by:   The FreeBSD Foundation
    
    (cherry picked from commit 26f76aea2d276aacb69a1f9d78558d6107155aed)
---
 sys/kern/kern_tc.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/sys/kern/kern_tc.c b/sys/kern/kern_tc.c
index f06665a69488..469c5fa12c82 100644
--- a/sys/kern/kern_tc.c
+++ b/sys/kern/kern_tc.c
@@ -1355,6 +1355,7 @@ static void
 tc_windup(struct bintime *new_boottimebin)
 {
 	struct bintime bt;
+	struct timecounter *tc;
 	struct timehands *th, *tho;
 	u_int delta, ncount, ogen;
 	int i;
@@ -1383,9 +1384,10 @@ tc_windup(struct bintime *new_boottimebin)
 	 * changing timecounters, a counter value from the new timecounter.
 	 * Update the offset fields accordingly.
 	 */
+	tc = atomic_load_ptr(&timecounter);
 	delta = tc_delta(th);
-	if (th->th_counter != timecounter)
-		ncount = timecounter->tc_get_timecount(timecounter);
+	if (th->th_counter != tc)
+		ncount = tc->tc_get_timecount(tc);
 	else
 		ncount = 0;
 #ifdef FFCLOCK
@@ -1440,17 +1442,17 @@ tc_windup(struct bintime *new_boottimebin)
 	bintime2timespec(&bt, &th->th_nanotime);
 
 	/* Now is a good time to change timecounters. */
-	if (th->th_counter != timecounter) {
+	if (th->th_counter != tc) {
 #ifndef __arm__
-		if ((timecounter->tc_flags & TC_FLAGS_C2STOP) != 0)
+		if ((tc->tc_flags & TC_FLAGS_C2STOP) != 0)
 			cpu_disable_c2_sleep++;
 		if ((th->th_counter->tc_flags & TC_FLAGS_C2STOP) != 0)
 			cpu_disable_c2_sleep--;
 #endif
-		th->th_counter = timecounter;
+		th->th_counter = tc;
 		th->th_offset_count = ncount;
-		tc_min_ticktock_freq = max(1, timecounter->tc_frequency /
-		    (((uint64_t)timecounter->tc_counter_mask + 1) / 3));
+		tc_min_ticktock_freq = max(1, tc->tc_frequency /
+		    (((uint64_t)tc->tc_counter_mask + 1) / 3));
 		recalculate_scaling_factor_and_large_delta(th);
 #ifdef FFCLOCK
 		ffclock_change_tc(th);