Fix race condition in calculate_now (#860)

* Fix race condition in calculate_now

* Add changelog

* Update changelog

* Refine comment

* More comment fixes

rtic-monotonics/CHANGELOG.md

@@ -13,6 +13,7 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 - Fix race condition in `nrf::rtc`.
 - Fix errata in `nrf::rtc`.
 - Add internal counter integrity check to all half-period based monotonics.
+- Apply race condition fixes from `rtic-time`.
 
 ## v1.4.0 - 2023-12-04
 

rtic-monotonics/src/imxrt.rs

@@ -212,7 +212,7 @@ macro_rules! make_timer {
                 let gpt = unsafe{ $timer::instance() };
 
                 Self::Instant::from_ticks(calculate_now(
-                    $period.load(Ordering::Relaxed),
+                    || $period.load(Ordering::Relaxed),
                     || ral::read_reg!(ral::gpt, gpt, CNT)
                 ))
             }

rtic-monotonics/src/nrf/rtc.rs

@@ -224,7 +224,7 @@ macro_rules! make_rtc {
             fn now() -> Self::Instant {
                 let rtc = unsafe { &*$rtc::PTR };
                 Self::Instant::from_ticks(calculate_now(
-                    $overflow.load(Ordering::Relaxed),
+                    || $overflow.load(Ordering::Relaxed),
                     || TimerValueU24(rtc.counter.read().bits())
                 ))
             }

rtic-monotonics/src/nrf/timer.rs

@@ -242,7 +242,7 @@ macro_rules! make_timer {
                 let timer = unsafe { &*$timer::PTR };
 
                 Self::Instant::from_ticks(calculate_now(
-                    $overflow.load(Ordering::Relaxed),
+                    || $overflow.load(Ordering::Relaxed),
                     || {
                         timer.tasks_capture[3].write(|w| unsafe { w.bits(1) });
                         timer.cc[3].read().bits()

rtic-monotonics/src/stm32.rs

@@ -234,7 +234,7 @@ macro_rules! make_timer {
 
             fn now() -> Self::Instant {
                 Self::Instant::from_ticks(calculate_now(
-                    $overflow.load(Ordering::Relaxed),
+                    || $overflow.load(Ordering::Relaxed),
                     || $timer.cnt().read().cnt()
                 ))
             }