timekeeping: Move timekeeper_lock into tk_core

timekeeper_lock protects updates to struct tk_core but is not part of
struct tk_core. As long as there is only a single timekeeper, this is not a
problem. But when the timekeeper infrastructure will be reused for per ptp
clock timekeepers, timekeeper_lock needs to be part of tk_core.

Move the lock into tk_core, move initialisation of the lock and sequence
counter into timekeeping_init() and update all users of timekeeper_lock.

As this is touching all lock sites, convert them to use:

  guard(raw_spinlock_irqsave)(&tk_core.lock);

instead of lock/unlock functions whenever possible.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
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-v2-9-554456a44a15@linutronix.de

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 77e0a0fe77717ff04bb000c208219e8199e7cca8..5392a66e02b6183d7380f0567a08076b6b2b6a43 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -41,8 +41,6 @@ enum timekeeping_adv_mode {
        TK_ADV_FREQ
 };
 
-static DEFINE_RAW_SPINLOCK(timekeeper_lock);
-
 /*
  * The most important data for readout fits into a single 64 byte
  * cache line.
@@ -51,10 +49,8 @@ static struct {
        seqcount_raw_spinlock_t seq;
        struct timekeeper       timekeeper;
        struct timekeeper       shadow_timekeeper;
-} tk_core ____cacheline_aligned = {
-       .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock),
-};
-
+       raw_spinlock_t          lock;
+} tk_core ____cacheline_aligned;
 
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
@@ -118,13 +114,13 @@ unsigned long timekeeper_lock_irqsave(void)
 {
        unsigned long flags;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        return flags;
 }
 
 void timekeeper_unlock_irqrestore(unsigned long flags)
 {
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 }
 
 /*
@@ -216,7 +212,7 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
  * the tkr's clocksource may change between the read reference, and the
  * clock reference passed to the read function.  This can cause crashes if
  * the wrong clocksource is passed to the wrong read function.
- * This isn't necessary to use when holding the timekeeper_lock or doing
+ * This isn't necessary to use when holding the tk_core.lock or doing
  * a read of the fast-timekeeper tkrs (which is protected by its own locking
  * and update logic).
  */
@@ -708,13 +704,11 @@ static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
 int pvclock_gtod_register_notifier(struct notifier_block *nb)
 {
        struct timekeeper *tk = &tk_core.timekeeper;
-       unsigned long flags;
        int ret;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       guard(raw_spinlock_irqsave)(&tk_core.lock);
        ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
        update_pvclock_gtod(tk, true);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
        return ret;
 }
@@ -727,14 +721,8 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
  */
 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
 {
-       unsigned long flags;
-       int ret;
-
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
-       ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
-
-       return ret;
+       guard(raw_spinlock_irqsave)(&tk_core.lock);
+       return raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
 }
 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
 
@@ -782,7 +770,7 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
        tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
 }
 
-/* must hold timekeeper_lock */
+/* must hold tk_core.lock */
 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
 {
        if (action & TK_CLEAR_NTP) {
@@ -1491,7 +1479,7 @@ int do_settimeofday64(const struct timespec64 *ts)
        if (!timespec64_valid_settod(ts))
                return -EINVAL;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        timekeeping_forward_now(tk);
@@ -1511,7 +1499,7 @@ out:
        timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        /* Signal hrtimers about time change */
        clock_was_set(CLOCK_SET_WALL);
@@ -1541,7 +1529,7 @@ static int timekeeping_inject_offset(const struct timespec64 *ts)
        if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC)
                return -EINVAL;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        timekeeping_forward_now(tk);
@@ -1561,7 +1549,7 @@ error: /* even if we error out, we forwarded the time, so call update */
        timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        /* Signal hrtimers about time change */
        clock_was_set(CLOCK_SET_WALL);
@@ -1637,7 +1625,7 @@ static int change_clocksource(void *data)
                return 0;
        }
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        timekeeping_forward_now(tk);
@@ -1646,7 +1634,7 @@ static int change_clocksource(void *data)
        timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        if (old) {
                if (old->disable)
@@ -1801,7 +1789,9 @@ void __init timekeeping_init(void)
        struct timespec64 wall_time, boot_offset, wall_to_mono;
        struct timekeeper *tk = &tk_core.timekeeper;
        struct clocksource *clock;
-       unsigned long flags;
+
+       raw_spin_lock_init(&tk_core.lock);
+       seqcount_raw_spinlock_init(&tk_core.seq, &tkd->lock);
 
        read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
        if (timespec64_valid_settod(&wall_time) &&
@@ -1821,7 +1811,7 @@ void __init timekeeping_init(void)
         */
        wall_to_mono = timespec64_sub(boot_offset, wall_time);
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       guard(raw_spinlock_irqsave)(&tk_core.lock);
        write_seqcount_begin(&tk_core.seq);
        ntp_init();
 
@@ -1838,7 +1828,6 @@ void __init timekeeping_init(void)
        timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 }
 
 /* time in seconds when suspend began for persistent clock */
@@ -1919,7 +1908,7 @@ void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
        struct timekeeper *tk = &tk_core.timekeeper;
        unsigned long flags;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        suspend_timing_needed = false;
@@ -1931,7 +1920,7 @@ void timekeeping_inject_sleeptime64(const struct timespec64 *delta)
        timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        /* Signal hrtimers about time change */
        clock_was_set(CLOCK_SET_WALL | CLOCK_SET_BOOT);
@@ -1955,7 +1944,7 @@ void timekeeping_resume(void)
        clockevents_resume();
        clocksource_resume();
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        /*
@@ -1993,7 +1982,7 @@ void timekeeping_resume(void)
        timekeeping_suspended = 0;
        timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        touch_softlockup_watchdog();
 
@@ -2024,7 +2013,7 @@ int timekeeping_suspend(void)
 
        suspend_timing_needed = true;
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
        timekeeping_forward_now(tk);
        timekeeping_suspended = 1;
@@ -2063,7 +2052,7 @@ int timekeeping_suspend(void)
        timekeeping_update(tk, TK_MIRROR);
        halt_fast_timekeeper(tk);
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        tick_suspend();
        clocksource_suspend();
@@ -2323,7 +2312,7 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
        int shift = 0, maxshift;
        u64 offset;
 
-       guard(raw_spinlock_irqsave)(&timekeeper_lock);
+       guard(raw_spinlock_irqsave)(&tk_core.lock);
 
        /* Make sure we're fully resumed: */
        if (unlikely(timekeeping_suspended))
@@ -2708,7 +2697,7 @@ int do_adjtimex(struct __kernel_timex *txc)
        ktime_get_real_ts64(&ts);
        add_device_randomness(&ts, sizeof(ts));
 
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       raw_spin_lock_irqsave(&tk_core.lock, flags);
        write_seqcount_begin(&tk_core.seq);
 
        orig_tai = tai = tk->tai_offset;
@@ -2723,7 +2712,7 @@ int do_adjtimex(struct __kernel_timex *txc)
        }
 
        write_seqcount_end(&tk_core.seq);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+       raw_spin_unlock_irqrestore(&tk_core.lock, flags);
 
        audit_ntp_log(&ad);
 
@@ -2747,11 +2736,8 @@ int do_adjtimex(struct __kernel_timex *txc)
  */
 void hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
 {
-       unsigned long flags;
-
-       raw_spin_lock_irqsave(&timekeeper_lock, flags);
+       guard(raw_spinlock_irqsave)(&tk_core.lock);
        __hardpps(phase_ts, raw_ts);
-       raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 }
 EXPORT_SYMBOL(hardpps);
 #endif /* CONFIG_NTP_PPS */