On Mon, Aug 1, 2022 at 10:54 AM Hao Luo <haoluo@xxxxxxxxxx> wrote:
>
> 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 <yhs@xxxxxx>
> Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx>
> ---
> .../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.c
>
> diff --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
> +}
> +
[...]
> 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;
> +}
> +
[...]
