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Subject[PATCH v4 bpf-next 4/6] selftests/bpf: test deadlock from recursive bpf_task_storage_[get|delete]
Date
Add a test with recursive bpf_task_storage_[get|delete] from fentry
programs on bpf_local_storage_lookup and bpf_local_storage_update. Without
proper deadlock prevent mechanism, this test would cause deadlock.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
.../bpf/prog_tests/task_local_storage.c | 23 ++++++
.../selftests/bpf/progs/task_ls_recursion.c | 70 +++++++++++++++++++
2 files changed, 93 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/task_ls_recursion.c

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
index dbb7525cdd567..035c263aab1b1 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
@@ -8,6 +8,7 @@
#include <test_progs.h>
#include "task_local_storage.skel.h"
#include "task_local_storage_exit_creds.skel.h"
+#include "task_ls_recursion.skel.h"

static void test_sys_enter_exit(void)
{
@@ -60,10 +61,32 @@ static void test_exit_creds(void)
task_local_storage_exit_creds__destroy(skel);
}

+static void test_recursion(void)
+{
+ struct task_ls_recursion *skel;
+ int err;
+
+ skel = task_ls_recursion__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+ return;
+
+ err = task_ls_recursion__attach(skel);
+ if (!ASSERT_OK(err, "skel_attach"))
+ goto out;
+
+ /* trigger sys_enter, make sure it does not cause deadlock */
+ syscall(SYS_gettid);
+
+out:
+ task_ls_recursion__destroy(skel);
+}
+
void test_task_local_storage(void)
{
if (test__start_subtest("sys_enter_exit"))
test_sys_enter_exit();
if (test__start_subtest("exit_creds"))
test_exit_creds();
+ if (test__start_subtest("recursion"))
+ test_recursion();
}
diff --git a/tools/testing/selftests/bpf/progs/task_ls_recursion.c b/tools/testing/selftests/bpf/progs/task_ls_recursion.c
new file mode 100644
index 0000000000000..564583dca7c85
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_ls_recursion.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+ __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+ __uint(map_flags, BPF_F_NO_PREALLOC);
+ __type(key, int);
+ __type(value, long);
+} map_a SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+ __uint(map_flags, BPF_F_NO_PREALLOC);
+ __type(key, int);
+ __type(value, long);
+} map_b SEC(".maps");
+
+SEC("fentry/bpf_local_storage_lookup")
+int BPF_PROG(on_lookup)
+{
+ struct task_struct *task = bpf_get_current_task_btf();
+
+ bpf_task_storage_delete(&map_a, task);
+ bpf_task_storage_delete(&map_b, task);
+ return 0;
+}
+
+SEC("fentry/bpf_local_storage_update")
+int BPF_PROG(on_update)
+{
+ struct task_struct *task = bpf_get_current_task_btf();
+ long *ptr;
+
+ ptr = bpf_task_storage_get(&map_a, task, 0,
+ BPF_LOCAL_STORAGE_GET_F_CREATE);
+ if (ptr)
+ *ptr += 1;
+
+ ptr = bpf_task_storage_get(&map_b, task, 0,
+ BPF_LOCAL_STORAGE_GET_F_CREATE);
+ if (ptr)
+ *ptr += 1;
+
+ return 0;
+}
+
+SEC("tp_btf/sys_enter")
+int BPF_PROG(on_enter, struct pt_regs *regs, long id)
+{
+ struct task_struct *task;
+ long *ptr;
+
+ task = bpf_get_current_task_btf();
+ ptr = bpf_task_storage_get(&map_a, task, 0,
+ BPF_LOCAL_STORAGE_GET_F_CREATE);
+ if (ptr)
+ *ptr = 200;
+
+ ptr = bpf_task_storage_get(&map_b, task, 0,
+ BPF_LOCAL_STORAGE_GET_F_CREATE);
+ if (ptr)
+ *ptr = 100;
+ return 0;
+}
--
2.24.1
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