From: Hou Tao <houtao1@xxxxxxxxxx>
The test case creates 4 threads and then pins these 4 threads in CPU 0.
These 4 threads will run different bpf program through
bpf_prog_test_run_opts() and these bpf program will use bpf_obj_new()
and bpf_obj_drop() to allocate and free local kptrs concurrently.
Under preemptible kernel, bpf_obj_new() and bpf_obj_drop() may preempt
each other, bpf_obj_new() may return NULL and the test will fail before
applying these fixes as shown below:
test_preempted_bpf_ma_op:PASS:open_and_load 0 nsec
test_preempted_bpf_ma_op:PASS:attach 0 nsec
test_preempted_bpf_ma_op:PASS:no test prog 0 nsec
test_preempted_bpf_ma_op:PASS:no test prog 0 nsec
test_preempted_bpf_ma_op:PASS:no test prog 0 nsec
test_preempted_bpf_ma_op:PASS:no test prog 0 nsec
test_preempted_bpf_ma_op:PASS:pthread_create 0 nsec
test_preempted_bpf_ma_op:PASS:pthread_create 0 nsec
test_preempted_bpf_ma_op:PASS:pthread_create 0 nsec
test_preempted_bpf_ma_op:PASS:pthread_create 0 nsec
test_preempted_bpf_ma_op:PASS:run prog err 0 nsec
test_preempted_bpf_ma_op:PASS:run prog err 0 nsec
test_preempted_bpf_ma_op:PASS:run prog err 0 nsec
test_preempted_bpf_ma_op:PASS:run prog err 0 nsec
test_preempted_bpf_ma_op:FAIL:ENOMEM unexpected ENOMEM: got TRUE
#168 preempted_bpf_ma_op:FAIL
Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
.../bpf/prog_tests/preempted_bpf_ma_op.c | 89 +++++++++++++++
.../selftests/bpf/progs/preempted_bpf_ma_op.c | 106 ++++++++++++++++++
2 files changed, 195 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/preempted_bpf_ma_op.c
create mode 100644 tools/testing/selftests/bpf/progs/preempted_bpf_ma_op.c
diff --git a/tools/testing/selftests/bpf/prog_tests/preempted_bpf_ma_op.c b/tools/testing/selftests/bpf/prog_tests/preempted_bpf_ma_op.c
new file mode 100644
index 000000000000..3a2ec3923fca
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/preempted_bpf_ma_op.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#define _GNU_SOURCE
+#include <sched.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <test_progs.h>
+
+#include "preempted_bpf_ma_op.skel.h"
+
+#define ALLOC_THREAD_NR 4
+#define ALLOC_LOOP_NR 512
+
+struct alloc_ctx {
+ /* output */
+ int run_err;
+ /* input */
+ int fd;
+ bool *nomem_err;
+};
+
+static void *run_alloc_prog(void *data)
+{
+ struct alloc_ctx *ctx = data;
+ cpu_set_t cpu_set;
+ int i;
+
+ CPU_ZERO(&cpu_set);
+ CPU_SET(0, &cpu_set);
+ pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
+
+ for (i = 0; i < ALLOC_LOOP_NR && !*ctx->nomem_err; i++) {
+ LIBBPF_OPTS(bpf_test_run_opts, topts);
+ int err;
+
+ err = bpf_prog_test_run_opts(ctx->fd, &topts);
+ ctx->run_err |= err | topts.retval;
+ }
+
+ return NULL;
+}
+
+void test_preempted_bpf_ma_op(void)
+{
+ struct alloc_ctx ctx[ALLOC_THREAD_NR];
+ struct preempted_bpf_ma_op *skel;
+ pthread_t tid[ALLOC_THREAD_NR];
+ int i, err;
+
+ skel = preempted_bpf_ma_op__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ return;
+
+ err = preempted_bpf_ma_op__attach(skel);
+ if (!ASSERT_OK(err, "attach"))
+ goto out;
+
+ for (i = 0; i < ARRAY_SIZE(ctx); i++) {
+ struct bpf_program *prog;
+ char name[8];
+
+ snprintf(name, sizeof(name), "test%d", i);
+ prog = bpf_object__find_program_by_name(skel->obj, name);
+ if (!ASSERT_OK_PTR(prog, "no test prog"))
+ goto out;
+
+ ctx[i].run_err = 0;
+ ctx[i].fd = bpf_program__fd(prog);
+ ctx[i].nomem_err = &skel->bss->nomem_err;
+ }
+
+ memset(tid, 0, sizeof(tid));
+ for (i = 0; i < ARRAY_SIZE(tid); i++) {
+ err = pthread_create(&tid[i], NULL, run_alloc_prog, &ctx[i]);
+ if (!ASSERT_OK(err, "pthread_create"))
+ break;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(tid); i++) {
+ if (!tid[i])
+ break;
+ pthread_join(tid[i], NULL);
+ ASSERT_EQ(ctx[i].run_err, 0, "run prog err");
+ }
+
+ ASSERT_FALSE(skel->bss->nomem_err, "ENOMEM");
+out:
+ preempted_bpf_ma_op__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/preempted_bpf_ma_op.c b/tools/testing/selftests/bpf/progs/preempted_bpf_ma_op.c
new file mode 100644
index 000000000000..55907ef961bf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/preempted_bpf_ma_op.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#include "bpf_experimental.h"
+
+struct bin_data {
+ char data[256];
+ struct bpf_spin_lock lock;
+};
+
+struct map_value {
+ struct bin_data __kptr * data;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, int);
+ __type(value, struct map_value);
+ __uint(max_entries, 2048);
+} array SEC(".maps");
+
+char _license[] SEC("license") = "GPL";
+
+bool nomem_err = false;
+
+static int del_array(unsigned int i, int *from)
+{
+ struct map_value *value;
+ struct bin_data *old;
+
+ value = bpf_map_lookup_elem(&array, from);
+ if (!value)
+ return 1;
+
+ old = bpf_kptr_xchg(&value->data, NULL);
+ if (old)
+ bpf_obj_drop(old);
+
+ (*from)++;
+ return 0;
+}
+
+static int add_array(unsigned int i, int *from)
+{
+ struct bin_data *old, *new;
+ struct map_value *value;
+
+ value = bpf_map_lookup_elem(&array, from);
+ if (!value)
+ return 1;
+
+ new = bpf_obj_new(typeof(*new));
+ if (!new) {
+ nomem_err = true;
+ return 1;
+ }
+
+ old = bpf_kptr_xchg(&value->data, new);
+ if (old)
+ bpf_obj_drop(old);
+
+ (*from)++;
+ return 0;
+}
+
+static void del_then_add_array(int from)
+{
+ int i;
+
+ i = from;
+ bpf_loop(512, del_array, &i, 0);
+
+ i = from;
+ bpf_loop(512, add_array, &i, 0);
+}
+
+SEC("fentry/bpf_fentry_test1")
+int BPF_PROG2(test0, int, a)
+{
+ del_then_add_array(0);
+ return 0;
+}
+
+SEC("fentry/bpf_fentry_test2")
+int BPF_PROG2(test1, int, a, u64, b)
+{
+ del_then_add_array(512);
+ return 0;
+}
+
+SEC("fentry/bpf_fentry_test3")
+int BPF_PROG2(test2, char, a, int, b, u64, c)
+{
+ del_then_add_array(1024);
+ return 0;
+}
+
+SEC("fentry/bpf_fentry_test4")
+int BPF_PROG2(test3, void *, a, char, b, int, c, u64, d)
+{
+ del_then_add_array(1536);
+ return 0;
+}
--
2.29.2
