From 88bbf875bd90ad21c0486113a757895bbc66635c 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    | 17 +++++++++++--
 2 files changed, 39 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 56d7db55a0..50c33846ba 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: 2022-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
@@ -26,6 +26,19 @@ atomic_uint   *g_atomic32;
 atomic_ushort *g_atomic16;
 atomic_uchar  *g_atomic8;
 
+TEST_CASE("stdatomic - test_atomic_flag", "[newlib_stdatomic]")
+{
+    bool x8 = 0;
+    g_atomic8 = heap_caps_calloc(sizeof(*g_atomic8), 1, MALLOC_CAP_DEFAULT);
+
+    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);
+    free(g_atomic8);
+}
+
 TEST_CASE("stdatomic - test_64bit_atomics", "[newlib_stdatomic]")
 {
     unsigned long long x64 = 0;
@@ -262,7 +275,7 @@ TEST_CASE("stdatomic - test_" #NAME, "[newlib_stdatomic]")
   free(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) \