tests/tcg: add new threadcount test

Based on the original testcase by Nikolay Igotti.

Message-ID: <CAEme+7GLKg_dNsHizzTKDymX9HyD+Ph2iZ=WKhOw2XG+zhViXg@mail.gmail.com>
Signed-off-by: Nikolay Igotti <igotti@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Message-Id: <20200520140541.30256-15-alex.bennee@linaro.org>

tests/tcg/multiarch/Makefile.target

@@ -28,6 +28,8 @@ run-float_%: float_%
 
 testthread: LDFLAGS+=-lpthread
 
+threadcount: LDFLAGS+=-lpthread
+
 # We define the runner for test-mmap after the individual
 # architectures have defined their supported pages sizes. If no
 # additional page sizes are defined we only run the default test.

tests/tcg/multiarch/threadcount.c

@@ -0,0 +1,64 @@
+/*
+ * Thread Exerciser
+ *
+ * Unlike testthread which is mainly concerned about testing thread
+ * semantics this test is used to exercise the thread creation and
+ * accounting. A version of this test found a problem with clashing
+ * cpu_indexes which caused a break in plugin handling.
+ *
+ * Based on the original test case by Nikolay Igotti.
+ *
+ * Copyright (c) 2020 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <pthread.h>
+
+int max_threads = 10;
+
+typedef struct {
+    int delay;
+} ThreadArg;
+
+static void *thread_fn(void* varg)
+{
+    ThreadArg *arg = varg;
+    usleep(arg->delay);
+    free(arg);
+    return NULL;
+}
+
+int main(int argc, char **argv)
+{
+    int i;
+    pthread_t *threads;
+
+    if (argc > 1) {
+        max_threads = atoi(argv[1]);
+    }
+    threads = calloc(sizeof(pthread_t), max_threads);
+
+    for (i = 0; i < max_threads; i++) {
+        ThreadArg *arg = calloc(sizeof(ThreadArg), 1);
+        arg->delay = i * 100;
+        pthread_create(threads + i, NULL, thread_fn, arg);
+    }
+
+    printf("Created %d threads\n", max_threads);
+
+    /* sleep until roughly half the threads have "finished" */
+    usleep(max_threads * 50);
+
+    for (i = 0; i < max_threads; i++) {
+        pthread_join(threads[i], NULL);
+    }
+
+    printf("Done\n");
+
+    return 0;
+}