Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/testing/radix-tree/regression4.c b/tools/testing/radix-tree/regression4.c
new file mode 100644
index 0000000..cf4e5ab
--- /dev/null
+++ b/tools/testing/radix-tree/regression4.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "regression.h"
+
+static pthread_barrier_t worker_barrier;
+static int obj0, obj1;
+static RADIX_TREE(mt_tree, GFP_KERNEL);
+
+static void *reader_fn(void *arg)
+{
+ int i;
+ void *entry;
+
+ rcu_register_thread();
+ pthread_barrier_wait(&worker_barrier);
+
+ for (i = 0; i < 1000000; i++) {
+ rcu_read_lock();
+ entry = radix_tree_lookup(&mt_tree, 0);
+ rcu_read_unlock();
+ if (entry != &obj0) {
+ printf("iteration %d bad entry = %p\n", i, entry);
+ abort();
+ }
+ }
+
+ rcu_unregister_thread();
+
+ return NULL;
+}
+
+static void *writer_fn(void *arg)
+{
+ int i;
+
+ rcu_register_thread();
+ pthread_barrier_wait(&worker_barrier);
+
+ for (i = 0; i < 1000000; i++) {
+ radix_tree_insert(&mt_tree, 1, &obj1);
+ radix_tree_delete(&mt_tree, 1);
+ }
+
+ rcu_unregister_thread();
+
+ return NULL;
+}
+
+void regression4_test(void)
+{
+ pthread_t reader, writer;
+
+ printv(1, "regression test 4 starting\n");
+
+ radix_tree_insert(&mt_tree, 0, &obj0);
+ pthread_barrier_init(&worker_barrier, NULL, 2);
+
+ if (pthread_create(&reader, NULL, reader_fn, NULL) ||
+ pthread_create(&writer, NULL, writer_fn, NULL)) {
+ perror("pthread_create");
+ exit(1);
+ }
+
+ if (pthread_join(reader, NULL) || pthread_join(writer, NULL)) {
+ perror("pthread_join");
+ exit(1);
+ }
+
+ printv(1, "regression test 4 passed\n");
+}