From 3b1916ad06eb336a24371666890e3da8dfbd95b0 Mon Sep 17 00:00:00 2001
From: Alexey Lapshin <alexey.lapshin@espressif.com>
Date: Mon, 3 Feb 2025 16:02:32 +0700
Subject: [PATCH] fix(newlib): fix __atomic_test_and_set to ensure atomicity

Before the change described in
https://gcc.gnu.org/pipermail/gcc-patches/2023-September/631393.html it
appeared that inlining built-in GCC function __atomic_test_and_set() was
incorrect. It resulted in a non-atomic write.
For GCC toolchains which do not have such patch yet, this commit fixes
__atomic_test_and_set to be atomic in IDF's builds.
---
 .../newlib/platform_include/stdatomic.h       | 24 +++++++++++++++++++
 .../test_apps/newlib/main/test_stdatomic.c    | 16 +++++++++++--
 2 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 components/newlib/platform_include/stdatomic.h

diff --git a/components/newlib/platform_include/stdatomic.h b/components/newlib/platform_include/stdatomic.h
new file mode 100644
index 0000000000..8ba259d527
--- /dev/null
+++ b/components/newlib/platform_include/stdatomic.h
@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+#include_next "stdatomic.h"
+#ifndef __clang__
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline bool __atomic_test_and_set(volatile void *ptr, int memorder)
+{
+    return __atomic_exchange_1((bool *)ptr, true, memorder);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/components/newlib/test_apps/newlib/main/test_stdatomic.c b/components/newlib/test_apps/newlib/main/test_stdatomic.c
index 602dc45c03..6a7b734f8b 100644
--- a/components/newlib/test_apps/newlib/main/test_stdatomic.c
+++ b/components/newlib/test_apps/newlib/main/test_stdatomic.c
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
@@ -21,6 +21,18 @@ atomic_ushort g_atomic16;
 atomic_uchar  g_atomic8;
 
 
+TEST_CASE("stdatomic - test_atomic_flag", "[newlib_stdatomic]")
+{
+    bool x8 = 0;
+    g_atomic8 = 0;
+
+    x8 = atomic_flag_test_and_set(&g_atomic8);
+    TEST_ASSERT_EQUAL_HEX8(0x00, x8);
+    TEST_ASSERT_EQUAL_HEX8(0x01, g_atomic8);
+    atomic_flag_clear(&g_atomic8);
+    TEST_ASSERT_EQUAL_HEX8(0x00, g_atomic8);
+}
+
 TEST_CASE("stdatomic - test_64bit_atomics", "[newlib_stdatomic]")
 {
     unsigned long long x64 = 0;
@@ -248,7 +260,7 @@ TEST_CASE("stdatomic - test_" #NAME, "[newlib_stdatomic]")
   TEST_ASSERT_EQUAL##ASSERT_SUFFIX((FINAL), var_##NAME);                          \
 }
 
-// Note that the assert at the end is doing an excat bitwise comparison.
+// Note that the assert at the end is doing an exact bitwise comparison.
 // This easily can fail due to rounding errors. However, there is currently
 // no corresponding Unity assert macro for long double. USE THIS WITH CARE!
 #define TEST_RACE_OPERATION_LONG_DOUBLE(NAME, LHSTYPE, PRE, POST, INIT, FINAL) \