Re: [PATCH bpf-next v6 5/8] selftests/bpf: Test cgroup_iter.
From: Andrii Nakryiko <hidden>
Date: 2022-08-01 21:51:51
Also in:
bpf, cgroups, lkml
On Mon, Aug 1, 2022 at 10:54 AM Hao Luo [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Add a selftest for cgroup_iter. The selftest creates a mini cgroup tree of the following structure: ROOT (working cgroup) | PARENT / \ CHILD1 CHILD2 and tests the following scenarios: - invalid cgroup fd. - pre-order walk over descendants from PARENT. - post-order walk over descendants from PARENT. - walk of ancestors from PARENT. - early termination. Acked-by: Yonghong Song <redacted> Signed-off-by: Hao Luo <redacted> --- .../selftests/bpf/prog_tests/cgroup_iter.c | 193 ++++++++++++++++++ tools/testing/selftests/bpf/progs/bpf_iter.h | 7 + .../testing/selftests/bpf/progs/cgroup_iter.c | 39 ++++ 3 files changed, 239 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_iter.c create mode 100644 tools/testing/selftests/bpf/progs/cgroup_iter.cdiff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c b/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c new file mode 100644 index 000000000000..5dc843a3f507 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c@@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Google */ + +#include <test_progs.h> +#include <bpf/libbpf.h> +#include <bpf/btf.h> +#include "cgroup_iter.skel.h" +#include "cgroup_helpers.h" + +#define ROOT 0 +#define PARENT 1 +#define CHILD1 2 +#define CHILD2 3 +#define NUM_CGROUPS 4 + +#define PROLOGUE "prologue\n" +#define EPILOGUE "epilogue\n" + +#define format_expected_output1(cg_id1) \ + snprintf(expected_output, sizeof(expected_output), \ + PROLOGUE "%8llu\n" EPILOGUE, (cg_id1)) + +#define format_expected_output2(cg_id1, cg_id2) \ + snprintf(expected_output, sizeof(expected_output), \ + PROLOGUE "%8llu\n%8llu\n" EPILOGUE, \ + (cg_id1), (cg_id2)) + +#define format_expected_output3(cg_id1, cg_id2, cg_id3) \ + snprintf(expected_output, sizeof(expected_output), \ + PROLOGUE "%8llu\n%8llu\n%8llu\n" EPILOGUE, \ + (cg_id1), (cg_id2), (cg_id3)) +
you use format_expected_output{1,2} just once and
format_expected_output3 twice. Is it worth defining macros for that?
+const char *cg_path[] = {
+ "/", "/parent", "/parent/child1", "/parent/child2"
+};
+
+static int cg_fd[] = {-1, -1, -1, -1};
+static unsigned long long cg_id[] = {0, 0, 0, 0};
+static char expected_output[64];
+
+int setup_cgroups(void)
+{
+ int fd, i = 0;
+
+ for (i = 0; i < NUM_CGROUPS; i++) {
+ fd = create_and_get_cgroup(cg_path[i]);
+ if (fd < 0)
+ return fd;
+
+ cg_fd[i] = fd;
+ cg_id[i] = get_cgroup_id(cg_path[i]);
+ }
+ return 0;
+}
+
+void cleanup_cgroups(void)some more statics to cover (same for setup_cgroups)
+{
+ int i;
+
+ for (i = 0; i < NUM_CGROUPS; i++)
+ close(cg_fd[i]);
+}
+
+static void read_from_cgroup_iter(struct bpf_program *prog, int cgroup_fd,
+ int order, const char *testname)
+{
+ DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+ union bpf_iter_link_info linfo;
+ struct bpf_link *link;
+ int len, iter_fd;
+ static char buf[64];
+
+ memset(&linfo, 0, sizeof(linfo));
+ linfo.cgroup.cgroup_fd = cgroup_fd;
+ linfo.cgroup.traversal_order = order;
+ opts.link_info = &linfo;
+ opts.link_info_len = sizeof(linfo);
+
+ link = bpf_program__attach_iter(prog, &opts);
+ if (!ASSERT_OK_PTR(link, "attach_iter"))
+ return;
+
+ iter_fd = bpf_iter_create(bpf_link__fd(link));
+ if (iter_fd < 0)
+ goto free_link;
+
+ memset(buf, 0, sizeof(buf));
+ while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+ ;this is broken, in general, you are overriding buffer content with each call to len I think you intended to advance buf after each read() call (and reduce remaining available buf size)?
+
+ ASSERT_STREQ(buf, expected_output, testname);
+
+ /* read() after iter finishes should be ok. */
+ if (len == 0)
+ ASSERT_OK(read(iter_fd, buf, sizeof(buf)), "second_read");
+
+ close(iter_fd);
+free_link:
+ bpf_link__destroy(link);
+}
+
+/* Invalid cgroup. */
+static void test_invalid_cgroup(struct cgroup_iter *skel)
+{
+ DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+ union bpf_iter_link_info linfo;
+ struct bpf_link *link;
+
+ memset(&linfo, 0, sizeof(linfo));
+ linfo.cgroup.cgroup_fd = (__u32)-1;
+ opts.link_info = &linfo;
+ opts.link_info_len = sizeof(linfo);
+
+ link = bpf_program__attach_iter(skel->progs.cgroup_id_printer, &opts);
+ if (!ASSERT_ERR_PTR(link, "attach_iter"))
+ bpf_link__destroy(link);nit: you can call bpf_link__destroy() even if link is NULL or IS_ERR
+} +
[...]
quoted hunk ↗ jump to hunk
diff --git a/tools/testing/selftests/bpf/progs/cgroup_iter.c b/tools/testing/selftests/bpf/progs/cgroup_iter.c new file mode 100644 index 000000000000..2a34d146d6df --- /dev/null +++ b/tools/testing/selftests/bpf/progs/cgroup_iter.c@@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Google */ + +#include "bpf_iter.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +char _license[] SEC("license") = "GPL"; +volatile int terminate_early = 0; +volatile u64 terminal_cgroup = 0; +
nit: you shouldn't need volatile for non-const global variables. Did you see any problems without volatile?
+static inline u64 cgroup_id(struct cgroup *cgrp)
+{
+ return cgrp->kn->id;
+}
+[...]