pthread_mutex: move in from cpp-cheat

userland/posix/pthread_mutex.c

@@ -0,0 +1,52 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#pthread-mutex */
+
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+unsigned long long niters;
+unsigned long long global = 0;
+pthread_mutex_t main_thread_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void* main_thread(void *arg) {
+    (void)arg;
+    unsigned long long i;
+    for (i = 0; i < niters; ++i) {
+        pthread_mutex_lock(&main_thread_mutex);
+        global++;
+        pthread_mutex_unlock(&main_thread_mutex);
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv) {
+    pthread_t *threads;
+    unsigned long long i, nthreads;
+
+    /* CLI arguments. */
+    if (argc > 1) {
+        nthreads = strtoull(argv[1], NULL, 0);
+    } else {
+        nthreads = 2;
+    }
+    if (argc > 2) {
+        niters = strtoull(argv[2], NULL, 0);
+    } else {
+        niters = 10;
+    }
+    threads = malloc(sizeof(pthread_t) * nthreads);
+
+    /* Action */
+    for (i = 0; i < nthreads; ++i)
+        pthread_create(&threads[i], NULL, main_thread, NULL);
+    for (i = 0; i < nthreads; ++i)
+        pthread_join(threads[i], NULL);
+    assert(global == nthreads * niters);
+
+    /* Cleanup. */
+    free(threads);
+    return EXIT_SUCCESS;
+}