On Fri, Sep 5, 2025 at 8:13 AM Xu Kuohai xukuohai@huaweicloud.com wrote:
From: Xu Kuohai xukuohai@huawei.com
Add test for overwiret mode ring buffer. The test creates a bpf ring buffer in overwrite mode, then repeatlly reserves and commits data to check if the ring buffer works as expected both before and after overwrite happens.
Signed-off-by: Xu Kuohai xukuohai@huawei.com
tools/testing/selftests/bpf/Makefile | 3 +- .../selftests/bpf/prog_tests/ringbuf.c | 74 ++++++++++++++ .../bpf/progs/test_ringbuf_overwrite.c | 98 +++++++++++++++++++ 3 files changed, 174 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_overwrite.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 11d2a368db3e..e6c18e201555 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -499,7 +499,8 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c \ trace_printk.c trace_vprintk.c map_ptr_kern.c \ core_kern.c core_kern_overflow.c test_ringbuf.c \
test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c
test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c \test_ringbuf_overwrite.c# Generate both light skeleton and libbpf skeleton for these LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \ diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c index d1e4cb28a72c..205a51c725a7 100644 --- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c @@ -17,6 +17,7 @@ #include "test_ringbuf_n.lskel.h" #include "test_ringbuf_map_key.lskel.h" #include "test_ringbuf_write.lskel.h" +#include "test_ringbuf_overwrite.lskel.h"
#define EDONE 7777
@@ -497,6 +498,77 @@ static void ringbuf_map_key_subtest(void) test_ringbuf_map_key_lskel__destroy(skel_map_key); }
+static void ringbuf_overwrite_mode_subtest(void) +{
unsigned long size, len1, len2, len3, len4, len5;unsigned long expect_avail_data, expect_prod_pos, expect_over_pos;struct test_ringbuf_overwrite_lskel *skel;int err;skel = test_ringbuf_overwrite_lskel__open();if (!ASSERT_OK_PTR(skel, "skel_open"))return;size = 0x1000;len1 = 0x800;len2 = 0x400;len3 = size - len1 - len2 - BPF_RINGBUF_HDR_SZ * 3; /* 0x3e8 */len4 = len3 - 8; /* 0x3e0 */len5 = len3; /* retry with len3 */skel->maps.ringbuf.max_entries = size;skel->rodata->LEN1 = len1;skel->rodata->LEN2 = len2;skel->rodata->LEN3 = len3;skel->rodata->LEN4 = len4;skel->rodata->LEN5 = len5;skel->bss->pid = getpid();err = test_ringbuf_overwrite_lskel__load(skel);if (!ASSERT_OK(err, "skel_load"))goto cleanup;err = test_ringbuf_overwrite_lskel__attach(skel);if (!ASSERT_OK(err, "skel_attach"))goto cleanup;syscall(__NR_getpgid);ASSERT_EQ(skel->bss->reserve1_fail, 0, "reserve 1");ASSERT_EQ(skel->bss->reserve2_fail, 0, "reserve 2");ASSERT_EQ(skel->bss->reserve3_fail, 1, "reserve 3");ASSERT_EQ(skel->bss->reserve4_fail, 0, "reserve 4");ASSERT_EQ(skel->bss->reserve5_fail, 0, "reserve 5");CHECK(skel->bss->ring_size != size,"check_ring_size", "exp %lu, got %lu\n",size, skel->bss->ring_size);
we don't use legacy CHECK() macros anymore, please use only ASSERT_xxx
expect_avail_data = len2 + len4 + len5 + 3 * BPF_RINGBUF_HDR_SZ;CHECK(skel->bss->avail_data != expect_avail_data,"check_avail_size", "exp %lu, got %lu\n",expect_avail_data, skel->bss->avail_data);CHECK(skel->bss->cons_pos != 0,"check_cons_pos", "exp 0, got %lu\n",skel->bss->cons_pos);expect_prod_pos = len1 + len2 + len4 + len5 + 4 * BPF_RINGBUF_HDR_SZ;CHECK(skel->bss->prod_pos != expect_prod_pos,"check_prod_pos", "exp %lu, got %lu\n",expect_prod_pos, skel->bss->prod_pos);expect_over_pos = len1 + BPF_RINGBUF_HDR_SZ;CHECK(skel->bss->over_pos != expect_over_pos,"check_over_pos", "exp %lu, got %lu\n",(unsigned long)expect_over_pos, skel->bss->over_pos);test_ringbuf_overwrite_lskel__detach(skel);+cleanup:
test_ringbuf_overwrite_lskel__destroy(skel);+}
void test_ringbuf(void) { if (test__start_subtest("ringbuf")) @@ -507,4 +579,6 @@ void test_ringbuf(void) ringbuf_map_key_subtest(); if (test__start_subtest("ringbuf_write")) ringbuf_write_subtest();
if (test__start_subtest("ringbuf_overwrite_mode"))ringbuf_overwrite_mode_subtest();} diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_overwrite.c b/tools/testing/selftests/bpf/progs/test_ringbuf_overwrite.c new file mode 100644 index 000000000000..da89ba12a75c --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_overwrite.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2025. Huawei Technologies Co., Ltd */
+#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include "bpf_misc.h"
+char _license[] SEC("license") = "GPL";
+struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);__uint(map_flags, BPF_F_OVERWRITE);+} ringbuf SEC(".maps");
+int pid;
+const volatile unsigned long LEN1; +const volatile unsigned long LEN2; +const volatile unsigned long LEN3; +const volatile unsigned long LEN4; +const volatile unsigned long LEN5;
+long reserve1_fail = 0; +long reserve2_fail = 0; +long reserve3_fail = 0; +long reserve4_fail = 0; +long reserve5_fail = 0;
+unsigned long avail_data = 0; +unsigned long ring_size = 0; +unsigned long cons_pos = 0; +unsigned long prod_pos = 0; +unsigned long over_pos = 0;
+SEC("fentry/" SYS_PREFIX "sys_getpgid") +int test_overwrite_ringbuf(void *ctx) +{
char *rec1, *rec2, *rec3, *rec4, *rec5;int cur_pid = bpf_get_current_pid_tgid() >> 32;if (cur_pid != pid)return 0;rec1 = bpf_ringbuf_reserve(&ringbuf, LEN1, 0);if (!rec1) {reserve1_fail = 1;return 0;}rec2 = bpf_ringbuf_reserve(&ringbuf, LEN2, 0);if (!rec2) {bpf_ringbuf_discard(rec1, 0);reserve2_fail = 1;return 0;}rec3 = bpf_ringbuf_reserve(&ringbuf, LEN3, 0);/* expect failure */if (!rec3) {reserve3_fail = 1;} else {bpf_ringbuf_discard(rec1, 0);bpf_ringbuf_discard(rec2, 0);bpf_ringbuf_discard(rec3, 0);return 0;}rec4 = bpf_ringbuf_reserve(&ringbuf, LEN4, 0);if (!rec4) {reserve4_fail = 1;bpf_ringbuf_discard(rec1, 0);bpf_ringbuf_discard(rec2, 0);return 0;}bpf_ringbuf_submit(rec1, 0);bpf_ringbuf_submit(rec2, 0);bpf_ringbuf_submit(rec4, 0);rec5 = bpf_ringbuf_reserve(&ringbuf, LEN5, 0);if (!rec5) {reserve5_fail = 1;return 0;}for (int i = 0; i < LEN3; i++)rec5[i] = 0xdd;bpf_ringbuf_submit(rec5, 0);ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE);avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA);cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS);prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS);over_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_OVER_POS);return 0;+}
2.43.0