From a386fcc9f917cab08770027a5e5293ccf8faa1f8 Mon Sep 17 00:00:00 2001
From: Balazs Racz <balazs.racz@gmail.com>
Date: Sat, 3 Feb 2024 06:36:53 -0800
Subject: [PATCH] Fixes another (smaller) race condition in ESP32's select
 wakeup.

The wakeup_from_isr routine consults the pendingWakeup_ and inSelect_ variables.
These variables need to be locked, because multi-core ESP32's could run an isr
on one core and othercode on a different core.

Moves the atomic lock from esp_wakeup_from_isr into OSSelectWakeup::wakeup_from_isr.
---
 src/os/OSSelectWakeup.cxx | 1 -
 src/os/OSSelectWakeup.hxx | 4 ++++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/os/OSSelectWakeup.cxx b/src/os/OSSelectWakeup.cxx
index 50efb44ac..d3ed3784f 100644
--- a/src/os/OSSelectWakeup.cxx
+++ b/src/os/OSSelectWakeup.cxx
@@ -240,7 +240,6 @@ void OSSelectWakeup::esp_wakeup()
 /// call from within an ISR context.
 void OSSelectWakeup::esp_wakeup_from_isr()
 {
-    AtomicHolder h(this);
     BaseType_t woken = pdFALSE;
 
     // If our VFS FD is not set in the except fd_set we can exit early.
diff --git a/src/os/OSSelectWakeup.hxx b/src/os/OSSelectWakeup.hxx
index 57f1ea708..ed45a6adf 100644
--- a/src/os/OSSelectWakeup.hxx
+++ b/src/os/OSSelectWakeup.hxx
@@ -159,6 +159,10 @@ public:
 #if OPENMRN_FEATURE_RTOS_FROM_ISR
     void wakeup_from_isr()
     {
+#if defined(ESP_PLATFORM)
+        // On multi-core ESP32s we need to lock objects even in ISRs.
+        AtomicHolder h(this);
+#endif
         pendingWakeup_ = true;
         if (inSelect_)
         {