From: Hou Tao <houtao1@xxxxxxxxxx>
One test demonstrates the reentrancy of hash map update fails, and
another one shows concureently updates of the same hash map bucket
succeed.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/htab_update.c | 126 ++++++++++++++++++
.../testing/selftests/bpf/progs/htab_update.c | 29 ++++
2 files changed, 155 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/htab_update.c
create mode 100644 tools/testing/selftests/bpf/progs/htab_update.c
diff --git a/tools/testing/selftests/bpf/prog_tests/htab_update.c b/tools/testing/selftests/bpf/prog_tests/htab_update.c
new file mode 100644
index 000000000000..e2a4034daa79
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/htab_update.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2022. Huawei Technologies Co., Ltd */
+#define _GNU_SOURCE
+#include <sched.h>
+#include <stdbool.h>
+#include <test_progs.h>
+#include "htab_update.skel.h"
+
+struct htab_update_ctx {
+ int fd;
+ int loop;
+ bool stop;
+};
+
+static void test_reenter_update(void)
+{
+ struct htab_update *skel;
+ unsigned int key, value;
+ int err;
+
+ skel = htab_update__open();
+ if (!ASSERT_OK_PTR(skel, "htab_update__open"))
+ return;
+
+ /* lookup_elem_raw() may be inlined and find_kernel_btf_id() will return -ESRCH */
+ bpf_program__set_autoload(skel->progs.lookup_elem_raw, true);
+ err = htab_update__load(skel);
+ if (!ASSERT_TRUE(!err || err == -ESRCH, "htab_update__load") || err)
+ goto out;
+
+ skel->bss->pid = getpid();
+ err = htab_update__attach(skel);
+ if (!ASSERT_OK(err, "htab_update__attach"))
+ goto out;
+
+ /* Will trigger the reentrancy of bpf_map_update_elem() */
+ key = 0;
+ value = 0;
+ err = bpf_map_update_elem(bpf_map__fd(skel->maps.htab), &key, &value, 0);
+ if (!ASSERT_OK(err, "add element"))
+ goto out;
+
+ ASSERT_EQ(skel->bss->update_err, -EBUSY, "no reentrancy");
+out:
+ htab_update__destroy(skel);
+}
+
+static void *htab_update_thread(void *arg)
+{
+ struct htab_update_ctx *ctx = arg;
+ cpu_set_t cpus;
+ int i;
+
+ /* Pin on CPU 0 */
+ CPU_ZERO(&cpus);
+ CPU_SET(0, &cpus);
+ pthread_setaffinity_np(pthread_self(), sizeof(cpus), &cpus);
+
+ i = 0;
+ while (i++ < ctx->loop && !ctx->stop) {
+ unsigned int key = 0, value = 0;
+ int err;
+
+ err = bpf_map_update_elem(ctx->fd, &key, &value, 0);
+ if (err) {
+ ctx->stop = true;
+ return (void *)(long)err;
+ }
+ }
+
+ return NULL;
+}
+
+static void test_concurrent_update(void)
+{
+ struct htab_update_ctx ctx;
+ struct htab_update *skel;
+ unsigned int i, nr;
+ pthread_t *tids;
+ int err;
+
+ skel = htab_update__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "htab_update__open_and_load"))
+ return;
+
+ ctx.fd = bpf_map__fd(skel->maps.htab);
+ ctx.loop = 1000;
+ ctx.stop = false;
+
+ nr = 4;
+ tids = calloc(nr, sizeof(*tids));
+ if (!ASSERT_NEQ(tids, NULL, "no mem"))
+ goto out;
+
+ for (i = 0; i < nr; i++) {
+ err = pthread_create(&tids[i], NULL, htab_update_thread, &ctx);
+ if (!ASSERT_OK(err, "pthread_create")) {
+ unsigned int j;
+
+ ctx.stop = true;
+ for (j = 0; j < i; j++)
+ pthread_join(tids[j], NULL);
+ goto out;
+ }
+ }
+
+ for (i = 0; i < nr; i++) {
+ void *thread_err = NULL;
+
+ pthread_join(tids[i], &thread_err);
+ ASSERT_EQ(thread_err, NULL, "update error");
+ }
+
+out:
+ if (tids)
+ free(tids);
+ htab_update__destroy(skel);
+}
+
+void test_htab_update(void)
+{
+ if (test__start_subtest("reenter_update"))
+ test_reenter_update();
+ if (test__start_subtest("concurrent_update"))
+ test_concurrent_update();
+}
diff --git a/tools/testing/selftests/bpf/progs/htab_update.c b/tools/testing/selftests/bpf/progs/htab_update.c
new file mode 100644
index 000000000000..7481bb30b29b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/htab_update.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2022. Huawei Technologies Co., Ltd */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+} htab SEC(".maps");
+
+int pid = 0;
+int update_err = 0;
+
+SEC("?fentry/lookup_elem_raw")
+int lookup_elem_raw(void *ctx)
+{
+ __u32 key = 0, value = 1;
+
+ if ((bpf_get_current_pid_tgid() >> 32) != pid)
+ return 0;
+
+ update_err = bpf_map_update_elem(&htab, &key, &value, 0);
+ return 0;
+}
--
2.29.2
