Adding upstream version 6.9.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 34 insertions, 50 deletions

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index e5b260aa0e..4d50d53ac7 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -20,6 +20,16 @@
 #include "tick-internal.h"
 #include "timekeeping_internal.h"
 
+static noinline u64 cycles_to_nsec_safe(struct clocksource *cs, u64 start, u64 end)
+{
+	u64 delta = clocksource_delta(end, start, cs->mask);
+
+	if (likely(delta < cs->max_cycles))
+		return clocksource_cyc2ns(delta, cs->mult, cs->shift);
+
+	return mul_u64_u32_shr(delta, cs->mult, cs->shift);
+}
+
 /**
  * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
  * @mult:	pointer to mult variable
@@ -222,8 +232,8 @@ enum wd_read_status {
 static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow)
 {
 	unsigned int nretries, max_retries;
-	u64 wd_end, wd_end2, wd_delta;
 	int64_t wd_delay, wd_seq_delay;
+	u64 wd_end, wd_end2;
 
 	max_retries = clocksource_get_max_watchdog_retry();
 	for (nretries = 0; nretries <= max_retries; nretries++) {
@@ -234,9 +244,7 @@ static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow,
 		wd_end2 = watchdog->read(watchdog);
 		local_irq_enable();
 
-		wd_delta = clocksource_delta(wd_end, *wdnow, watchdog->mask);
-		wd_delay = clocksource_cyc2ns(wd_delta, watchdog->mult,
-					      watchdog->shift);
+		wd_delay = cycles_to_nsec_safe(watchdog, *wdnow, wd_end);
 		if (wd_delay <= WATCHDOG_MAX_SKEW) {
 			if (nretries > 1 || nretries >= max_retries) {
 				pr_warn("timekeeping watchdog on CPU%d: %s retried %d times before success\n",
@@ -254,8 +262,7 @@ static enum wd_read_status cs_watchdog_read(struct clocksource *cs, u64 *csnow,
 		 * report system busy, reinit the watchdog and skip the current
 		 * watchdog test.
 		 */
-		wd_delta = clocksource_delta(wd_end2, wd_end, watchdog->mask);
-		wd_seq_delay = clocksource_cyc2ns(wd_delta, watchdog->mult, watchdog->shift);
+		wd_seq_delay = cycles_to_nsec_safe(watchdog, wd_end, wd_end2);
 		if (wd_seq_delay > WATCHDOG_MAX_SKEW/2)
 			goto skip_test;
 	}
@@ -366,8 +373,7 @@ void clocksource_verify_percpu(struct clocksource *cs)
 		delta = (csnow_end - csnow_mid) & cs->mask;
 		if (delta < 0)
 			cpumask_set_cpu(cpu, &cpus_ahead);
-		delta = clocksource_delta(csnow_end, csnow_begin, cs->mask);
-		cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift);
+		cs_nsec = cycles_to_nsec_safe(cs, csnow_begin, csnow_end);
 		if (cs_nsec > cs_nsec_max)
 			cs_nsec_max = cs_nsec;
 		if (cs_nsec < cs_nsec_min)
@@ -398,8 +404,8 @@ static inline void clocksource_reset_watchdog(void)
 
 static void clocksource_watchdog(struct timer_list *unused)
 {
-	u64 csnow, wdnow, cslast, wdlast, delta;
 	int64_t wd_nsec, cs_nsec, interval;
+	u64 csnow, wdnow, cslast, wdlast;
 	int next_cpu, reset_pending;
 	struct clocksource *cs;
 	enum wd_read_status read_ret;
@@ -456,12 +462,8 @@ static void clocksource_watchdog(struct timer_list *unused)
 			continue;
 		}
 
-		delta = clocksource_delta(wdnow, cs->wd_last, watchdog->mask);
-		wd_nsec = clocksource_cyc2ns(delta, watchdog->mult,
-					     watchdog->shift);
-
-		delta = clocksource_delta(csnow, cs->cs_last, cs->mask);
-		cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift);
+		wd_nsec = cycles_to_nsec_safe(watchdog, cs->wd_last, wdnow);
+		cs_nsec = cycles_to_nsec_safe(cs, cs->cs_last, csnow);
 		wdlast = cs->wd_last; /* save these in case we print them */
 		cslast = cs->cs_last;
 		cs->cs_last = csnow;
@@ -832,7 +834,7 @@ void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles)
  */
 u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now)
 {
-	u64 now, delta, nsec = 0;
+	u64 now, nsec = 0;
 
 	if (!suspend_clocksource)
 		return 0;
@@ -847,12 +849,8 @@ u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now)
 	else
 		now = suspend_clocksource->read(suspend_clocksource);
 
-	if (now > suspend_start) {
-		delta = clocksource_delta(now, suspend_start,
-					  suspend_clocksource->mask);
-		nsec = mul_u64_u32_shr(delta, suspend_clocksource->mult,
-				       suspend_clocksource->shift);
-	}
+	if (now > suspend_start)
+		nsec = cycles_to_nsec_safe(suspend_clocksource, suspend_start, now);
 
 	/*
 	 * Disable the suspend timer to save power if current clocksource is
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index d88b13076b..a47bcf71de 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -178,26 +178,6 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
 	}
 }
 
-#ifdef CONFIG_NO_HZ_FULL
-static void giveup_do_timer(void *info)
-{
-	int cpu = *(unsigned int *)info;
-
-	WARN_ON(tick_do_timer_cpu != smp_processor_id());
-
-	tick_do_timer_cpu = cpu;
-}
-
-static void tick_take_do_timer_from_boot(void)
-{
-	int cpu = smp_processor_id();
-	int from = tick_do_timer_boot_cpu;
-
-	if (from >= 0 && from != cpu)
-		smp_call_function_single(from, giveup_do_timer, &cpu, 1);
-}
-#endif
-
 /*
  * Setup the tick device
  */
@@ -221,19 +201,25 @@ static void tick_setup_device(struct tick_device *td,
 			tick_next_period = ktime_get();
 #ifdef CONFIG_NO_HZ_FULL
 			/*
-			 * The boot CPU may be nohz_full, in which case set
-			 * tick_do_timer_boot_cpu so the first housekeeping
-			 * secondary that comes up will take do_timer from
-			 * us.
+			 * The boot CPU may be nohz_full, in which case the
+			 * first housekeeping secondary will take do_timer()
+			 * from it.
 			 */
 			if (tick_nohz_full_cpu(cpu))
 				tick_do_timer_boot_cpu = cpu;
 
-		} else if (tick_do_timer_boot_cpu != -1 &&
-						!tick_nohz_full_cpu(cpu)) {
-			tick_take_do_timer_from_boot();
+		} else if (tick_do_timer_boot_cpu != -1 && !tick_nohz_full_cpu(cpu)) {
 			tick_do_timer_boot_cpu = -1;
-			WARN_ON(READ_ONCE(tick_do_timer_cpu) != cpu);
+			/*
+			 * The boot CPU will stay in periodic (NOHZ disabled)
+			 * mode until clocksource_done_booting() called after
+			 * smp_init() selects a high resolution clocksource and
+			 * timekeeping_notify() kicks the NOHZ stuff alive.
+			 *
+			 * So this WRITE_ONCE can only race with the READ_ONCE
+			 * check in tick_periodic() but this race is harmless.
+			 */
+			WRITE_ONCE(tick_do_timer_cpu, cpu);
 #endif
 		}