From b2350d954dca14dfde95e7512ad521ccab0e4108 Mon Sep 17 00:00:00 2001 From: Anna-Maria Behnsen Date: Wed, 9 Oct 2024 10:29:14 +0200 Subject: [PATCH] timekeeping: Rework timekeeping_resume() 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. While the sequence count held time is not relevant for the resume path as there is no concurrency, there is no reason to have this function different than all the other update sites. Convert timekeeping_inject_offset() to use this scheme and cleanup the variable declaration while at it. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Acked-by: John Stultz Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-21-554456a44a15@linutronix.de --- kernel/time/timekeeping.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 9552bc76f386..94f68e7ffc9d 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1943,12 +1943,12 @@ void timekeeping_inject_sleeptime64(const struct timespec64 *delta) */ void timekeeping_resume(void) { - struct timekeeper *tk = &tk_core.timekeeper; - struct clocksource *clock = tk->tkr_mono.clock; - unsigned long flags; + struct timekeeper *tks = &tk_core.shadow_timekeeper; + struct clocksource *clock = tks->tkr_mono.clock; struct timespec64 ts_new, ts_delta; - u64 cycle_now, nsec; bool inject_sleeptime = false; + u64 cycle_now, nsec; + unsigned long flags; read_persistent_clock64(&ts_new); @@ -1956,7 +1956,6 @@ void timekeeping_resume(void) clocksource_resume(); raw_spin_lock_irqsave(&tk_core.lock, flags); - write_seqcount_begin(&tk_core.seq); /* * After system resumes, we need to calculate the suspended time and @@ -1970,7 +1969,7 @@ void timekeeping_resume(void) * The less preferred source will only be tried if there is no better * usable source. The rtc part is handled separately in rtc core code. */ - cycle_now = tk_clock_read(&tk->tkr_mono); + cycle_now = tk_clock_read(&tks->tkr_mono); nsec = clocksource_stop_suspend_timing(clock, cycle_now); if (nsec > 0) { ts_delta = ns_to_timespec64(nsec); @@ -1982,17 +1981,16 @@ void timekeeping_resume(void) if (inject_sleeptime) { suspend_timing_needed = false; - __timekeeping_inject_sleeptime(tk, &ts_delta); + __timekeeping_inject_sleeptime(tks, &ts_delta); } /* Re-base the last cycle value */ - tk->tkr_mono.cycle_last = cycle_now; - tk->tkr_raw.cycle_last = cycle_now; + tks->tkr_mono.cycle_last = cycle_now; + tks->tkr_raw.cycle_last = cycle_now; - tk->ntp_error = 0; + tks->ntp_error = 0; timekeeping_suspended = 0; - timekeeping_update(&tk_core, tk, TK_MIRROR | TK_CLOCK_WAS_SET); - write_seqcount_end(&tk_core.seq); + timekeeping_update_from_shadow(&tk_core, TK_CLOCK_WAS_SET); raw_spin_unlock_irqrestore(&tk_core.lock, flags); touch_softlockup_watchdog();