From d87e242ae12911ad5ebd55f4acd93b04b460a17d Mon Sep 17 00:00:00 2001
From: "Dirk O. Kaar" <dok@dok-net.net>
Date: Sat, 1 Jul 2023 16:40:53 +0200
Subject: [PATCH] ISR safety.

---
 cores/esp8266/Schedule.cpp | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/cores/esp8266/Schedule.cpp b/cores/esp8266/Schedule.cpp
index 0074570b93..053f804758 100644
--- a/cores/esp8266/Schedule.cpp
+++ b/cores/esp8266/Schedule.cpp
@@ -119,15 +119,15 @@ bool schedule_recurrent_function_us(const std::function<bool(void)>& fn,
     item->mFunc = fn;
     item->alarm = alarm;
 
+    esp8266::InterruptLock lockAllInterruptsInThisScope;
+
     // prevent new item overwriting an already expired rTarget.
-    const int32_t rRemaining = rTarget - micros();
-    if (!rFirst || (rRemaining > 0 && static_cast<uint32_t>(rRemaining) > item->callNow.remaining()))
+    const int32_t remaining = rTarget - micros();
+    if (!rFirst || (remaining > 0 && static_cast<uint32_t>(remaining) > item->callNow.remaining()))
     {
         rTarget = micros() + item->callNow.remaining();
     }
 
-    esp8266::InterruptLock lockAllInterruptsInThisScope;
-
     if (rLast)
     {
         rLast->mNext = item;
@@ -145,8 +145,8 @@ uint32_t get_scheduled_recurrent_delay_us()
 {
     if (!rFirst) return ~static_cast<uint32_t>(0);
     // handle already expired rTarget.
-    const int32_t rRemaining = rTarget - micros();
-    return (rRemaining > 0) ? static_cast<uint32_t>(rRemaining) : 0;
+    const int32_t remaining = rTarget - micros();
+    return (remaining > 0) ? static_cast<uint32_t>(remaining) : 0;
 }
 
 void run_scheduled_functions()
@@ -248,9 +248,12 @@ void run_scheduled_recurrent_functions()
         {
             prev = current;
             current = current->mNext;
+
+            esp8266::InterruptLock lockAllInterruptsInThisScope;
+
             // prevent current item overwriting an already expired rTarget.
-            const int32_t rRemaining = rTarget - micros();
-            if (rRemaining > 0 && static_cast<uint32_t>(rRemaining) > current->callNow.remaining())
+            const int32_t remaining = rTarget - micros();
+            if (remaining > 0 && static_cast<uint32_t>(remaining) > current->callNow.remaining())
             {
                 rTarget = micros() + current->callNow.remaining();
             }