Re: [PATCH bpf-next v5 2/2] selftests: bpf: test BPF_PROG_QUERY for progs attached to sockmap

[zhudi (E)]

> On Thu, Jan 13, 2022 at 1:01 AM Di Zhu <zhudi2@xxxxxxxxxx> wrote:
> >
> > Add test for querying progs attached to sockmap. we use an existing
> > libbpf query interface to query prog cnt before and after progs
> > attaching to sockmap and check whether the queried prog id is right.
> >
> > Signed-off-by: Di Zhu <zhudi2@xxxxxxxxxx>
> > Acked-by: Yonghong Song <yhs@xxxxxx>
> > ---
> >  .../selftests/bpf/prog_tests/sockmap_basic.c  | 70 +++++++++++++++++++
> >  .../bpf/progs/test_sockmap_progs_query.c      | 24 +++++++
> >  2 files changed, 94 insertions(+)
> >  create mode 100644
> tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> > index 85db0f4cdd95..06923ea44bad 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> > @@ -8,6 +8,7 @@
> >  #include "test_sockmap_update.skel.h"
> >  #include "test_sockmap_invalid_update.skel.h"
> >  #include "test_sockmap_skb_verdict_attach.skel.h"
> > +#include "test_sockmap_progs_query.skel.h"
> >  #include "bpf_iter_sockmap.skel.h"
> >
> >  #define TCP_REPAIR             19      /* TCP sock is under repair
> right now */
> > @@ -315,6 +316,69 @@ static void test_sockmap_skb_verdict_attach(enum
> bpf_attach_type first,
> >         test_sockmap_skb_verdict_attach__destroy(skel);
> >  }
> >
> > +static __u32 query_prog_id(int prog_fd)
> > +{
> > +       struct bpf_prog_info info = {};
> > +       __u32 info_len = sizeof(info);
> > +       int err;
> > +
> > +       err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
> > +       if (!ASSERT_OK(err, "bpf_obj_get_info_by_fd") ||
> > +           !ASSERT_EQ(info_len, sizeof(info), "bpf_obj_get_info_by_fd"))
> > +               return 0;
> > +
> > +       return info.id;
> > +}
> > +
> > +static void test_sockmap_progs_query(enum bpf_attach_type attach_type)
> > +{
> > +       struct test_sockmap_progs_query *skel;
> > +       int err, map_fd, verdict_fd, duration = 0;
> > +       __u32 attach_flags = 0;
> > +       __u32 prog_ids[3] = {};
> > +       __u32 prog_cnt = 3;
> > +
> > +       skel = test_sockmap_progs_query__open_and_load();
> > +       if (!ASSERT_OK_PTR(skel,
> "test_sockmap_progs_query__open_and_load"))
> > +               return;
> > +
> > +       map_fd = bpf_map__fd(skel->maps.sock_map);
> > +
> > +       if (attach_type == BPF_SK_MSG_VERDICT)
> > +               verdict_fd =
> bpf_program__fd(skel->progs.prog_skmsg_verdict);
> > +       else
> > +               verdict_fd =
> bpf_program__fd(skel->progs.prog_skb_verdict);
> > +
> > +       err = bpf_prog_query(map_fd, attach_type, 0 /* query flags */,
> > +                            &attach_flags, prog_ids, &prog_cnt);
> > +       if (!ASSERT_OK(err, "bpf_prog_query failed"))
> > +               goto out;
> > +
> > +       if (!ASSERT_EQ(attach_flags,  0, "wrong attach_flags on query"))
> > +               goto out;
> > +
> > +       if (!ASSERT_EQ(prog_cnt, 0, "wrong program count on query"))
> > +               goto out;
> > +
> > +       err = bpf_prog_attach(verdict_fd, map_fd, attach_type, 0);
> > +       if (!ASSERT_OK(err, "bpf_prog_attach failed"))
> > +               goto out;
> > +
> > +       prog_cnt = 1;
> > +       err = bpf_prog_query(map_fd, attach_type, 0 /* query flags */,
> > +                            &attach_flags, prog_ids, &prog_cnt);
> > +
> > +       ASSERT_OK(err, "bpf_prog_query failed");
> > +       ASSERT_EQ(attach_flags, 0, "wrong attach_flags on query");
> > +       ASSERT_EQ(prog_cnt, 1, "wrong program count on query");
> > +       ASSERT_EQ(prog_ids[0], query_prog_id(verdict_fd),
> > +                 "wrong prog_ids on query");
> 
> See how much easier it is to follow these tests, why didn't you do the
> same with err, attach_flags and prog above?

It is recommended by Yonghong Song to increase the test coverage.

> 
> 
> > +
> > +       bpf_prog_detach2(verdict_fd, map_fd, attach_type);
> > +out:
> > +       test_sockmap_progs_query__destroy(skel);
> > +}
> > +
> >  void test_sockmap_basic(void)
> >  {
> >         if (test__start_subtest("sockmap create_update_free"))
> > @@ -341,4 +405,10 @@ void test_sockmap_basic(void)
> >
> test_sockmap_skb_verdict_attach(BPF_SK_SKB_STREAM_VERDICT,
> >
> BPF_SK_SKB_VERDICT);
> >         }
> > +       if (test__start_subtest("sockmap progs query")) {
> > +               test_sockmap_progs_query(BPF_SK_MSG_VERDICT);
> > +
> test_sockmap_progs_query(BPF_SK_SKB_STREAM_PARSER);
> > +
> test_sockmap_progs_query(BPF_SK_SKB_STREAM_VERDICT);
> > +               test_sockmap_progs_query(BPF_SK_SKB_VERDICT);
> 
> Why are these not separate subtests? What's the benefit of bundling
> them into one subtest?
> 

These are essentially doing the same thing, just for different program attach types.

> > +       }
> >  }
> > diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> b/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> > new file mode 100644
> > index 000000000000..9d58d61c0dee
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/test_sockmap_progs_query.c
> > @@ -0,0 +1,24 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +#include "vmlinux.h"
> > +#include <bpf/bpf_helpers.h>
> > +
> > +struct {
> > +       __uint(type, BPF_MAP_TYPE_SOCKMAP);
> > +       __uint(max_entries, 1);
> > +       __type(key, __u32);
> > +       __type(value, __u64);
> > +} sock_map SEC(".maps");
> > +
> > +SEC("sk_skb")
> > +int prog_skb_verdict(struct __sk_buff *skb)
> > +{
> > +       return SK_PASS;
> > +}
> > +
> > +SEC("sk_msg")
> > +int prog_skmsg_verdict(struct sk_msg_md *msg)
> > +{
> > +       return SK_PASS;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> > --
> > 2.27.0
> >