tests: lib: Add newlib thread safety test
This commit adds a new test to verify the thread safety of the C
standard functions provided by newlib.
Only the memory management functions (malloc and free) are tested at
this time; this test will be further extended in the future, to verify
the thread safety and re-entrancy of all supported newlib functions.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
diff --git a/tests/lib/newlib/thread_safety/CMakeLists.txt b/tests/lib/newlib/thread_safety/CMakeLists.txt
new file mode 100644
index 0000000..927ab9e
--- /dev/null
+++ b/tests/lib/newlib/thread_safety/CMakeLists.txt
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(newlib_thread_safety)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})
diff --git a/tests/lib/newlib/thread_safety/prj.conf b/tests/lib/newlib/thread_safety/prj.conf
new file mode 100644
index 0000000..618b3dd
--- /dev/null
+++ b/tests/lib/newlib/thread_safety/prj.conf
@@ -0,0 +1,3 @@
+CONFIG_ZTEST=y
+CONFIG_NEWLIB_LIBC=y
+CONFIG_TIMESLICE_SIZE=1
diff --git a/tests/lib/newlib/thread_safety/src/main.c b/tests/lib/newlib/thread_safety/src/main.c
new file mode 100644
index 0000000..e2f246f
--- /dev/null
+++ b/tests/lib/newlib/thread_safety/src/main.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2021 Stephanos Ioannidis <root@stephanos.io>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * @file Newlib thread safety test
+ *
+ * This file contains a set of tests to verify that the C standard functions
+ * provided by newlib are thread safe (i.e. synchronised) and that the thread-
+ * specific contexts are properly handled (i.e. re-entrant).
+ */
+
+#include <zephyr.h>
+#include <ztest.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define THREAD_COUNT (64)
+#define STACK_SIZE (512 + CONFIG_TEST_EXTRA_STACKSIZE)
+#define TEST_INTERVAL (30) /* seconds */
+
+static struct k_thread tdata[THREAD_COUNT];
+static K_THREAD_STACK_ARRAY_DEFINE(tstack, THREAD_COUNT, STACK_SIZE);
+
+void malloc_thread(void *p1, void *p2, void *p3)
+{
+ static atomic_t count;
+ bool *aborted = p1;
+ int *volatile ptr;
+ int val;
+
+ while (*aborted == false) {
+ /* Compute unique value specific to this iteration. */
+ val = atomic_inc(&count);
+
+ /* Allocate memory block and write a unique value to it. */
+ ptr = malloc(sizeof(int));
+ zassert_not_null(ptr, "Out of memory");
+ *ptr = val;
+
+ /* Busy wait to increase the likelihood of preemption. */
+ k_busy_wait(10);
+
+ /*
+ * Verify that the unique value previously written to the
+ * memory block is valid. This value will become corrupted if
+ * the newlib heap is not properly synchronised.
+ */
+ zassert_equal(*ptr, val, "Corrupted memory block");
+
+ /* Free memory block. */
+ free(ptr);
+ }
+}
+
+/**
+ * @brief Test thread safety of newlib memory management functions
+ *
+ * This test calls the malloc() and free() functions from multiple threads to
+ * verify that no corruption occurs in the newlib memory heap.
+ */
+void test_malloc_thread_safety(void)
+{
+ int i;
+ k_tid_t tid[THREAD_COUNT];
+ bool aborted = false;
+
+ /* Create worker threads. */
+ for (i = 0; i < ARRAY_SIZE(tid); i++) {
+ tid[i] = k_thread_create(&tdata[i], tstack[i], STACK_SIZE,
+ malloc_thread, &aborted, NULL, NULL,
+ K_PRIO_PREEMPT(0), 0, K_NO_WAIT);
+ }
+
+ TC_PRINT("Created %d worker threads.\n", THREAD_COUNT);
+
+ /* Wait and see if any failures occur. */
+ TC_PRINT("Waiting %d seconds to see if any failures occur ...\n",
+ TEST_INTERVAL);
+
+ k_sleep(K_SECONDS(TEST_INTERVAL));
+
+ /* Abort all worker threads. */
+ aborted = true;
+
+ for (i = 0; i < ARRAY_SIZE(tid); i++) {
+ k_thread_join(tid[i], K_FOREVER);
+ }
+}
+
+void test_main(void)
+{
+ ztest_test_suite(newlib_thread_safety,
+ ztest_unit_test(test_malloc_thread_safety));
+
+ ztest_run_test_suite(newlib_thread_safety);
+}
diff --git a/tests/lib/newlib/thread_safety/testcase.yaml b/tests/lib/newlib/thread_safety/testcase.yaml
new file mode 100644
index 0000000..45a4d0f
--- /dev/null
+++ b/tests/lib/newlib/thread_safety/testcase.yaml
@@ -0,0 +1,13 @@
+common:
+ filter: TOOLCHAIN_HAS_NEWLIB == 1
+ min_ram: 64
+ tags: clib newlib
+
+tests:
+ libraries.libc.newlib.thread_safety:
+ slow: true
+ libraries.libc.newlib_nano.thread_safety:
+ slow: true
+ filter: CONFIG_HAS_NEWLIB_LIBC_NANO
+ extra_configs:
+ - CONFIG_NEWLIB_LIBC_NANO=y
