[tip: timers/core] timekeeping: Rework timekeeping_inject_sleeptime64() to use shadow_timekeeper

["tip-bot2 for Anna-Maria Behnsen" <tip-bot2@linutronix.de>]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     2cc803915f351a845dc6c2e5e8ede1f09a2108d4
Gitweb:        https://git.kernel.org/tip/2cc803915f351a845dc6c2e5e8ede1f09a2108d4
Author:        Anna-Maria Behnsen <anna-maria@linutronix.de>
AuthorDate:    Wed, 09 Oct 2024 10:29:13 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 25 Oct 2024 16:41:13 +02:00

timekeeping: Rework timekeeping_inject_sleeptime64() to use shadow_timekeeper

Updates of the timekeeper can be done by operating on the shadow timekeeper
and afterwards copying the result into the real timekeeper. This has the
advantage, that the sequence count write protected region is kept as small
as possible.

Convert timekeeping_inject_sleeptime64() to use this scheme.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-20-554456a44a15@linutronix.de

---
 kernel/time/timekeeping.c | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4e0037d..9552bc7 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1924,22 +1924,14 @@ bool timekeeping_rtc_skipsuspend(void)
  */
 void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
 {
-	struct timekeeper *tk = &tk_core.timekeeper;
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&tk_core.lock, flags);
-	write_seqcount_begin(&tk_core.seq);
-
-	suspend_timing_needed = false;
-
-	timekeeping_forward_now(tk);
-
-	__timekeeping_inject_sleeptime(tk, delta);
-
-	timekeeping_update(&tk_core, tk, TK_UPDATE_ALL | TK_MIRROR);
+	scoped_guard(raw_spinlock_irqsave, &tk_core.lock) {
+		struct timekeeper *tks = &tk_core.shadow_timekeeper;
 
-	write_seqcount_end(&tk_core.seq);
-	raw_spin_unlock_irqrestore(&tk_core.lock, flags);
+		suspend_timing_needed = false;
+		timekeeping_forward_now(tks);
+		__timekeeping_inject_sleeptime(tks, delta);
+		timekeeping_update_from_shadow(&tk_core, TK_UPDATE_ALL);
+	}
 
 	/* Signal hrtimers about time change */
 	clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);