On Wed, May 22, 2019 at 03:24:38PM -0700, Stanislav Fomichev wrote:
> On 05/22, Roman Gushchin wrote:
> > Add a kselftest to cover bpf auto-detachment functionality.
> > The test creates a cgroup, associates some resources with it,
> > attaches a couple of bpf programs and deletes the cgroup.
> >
> > Then it checks that bpf programs are going away in 5 seconds.
> >
> > Expected output:
> > $ ./test_cgroup_attach
> > #override:PASS
> > #multi:PASS
> > #autodetach:PASS
> > test_cgroup_attach:PASS
> >
> > On a kernel without auto-detaching:
> > $ ./test_cgroup_attach
> > #override:PASS
> > #multi:PASS
> > #autodetach:FAIL
> > test_cgroup_attach:FAIL
> >
> > Signed-off-by: Roman Gushchin <guro@xxxxxx>
> > ---
> > .../selftests/bpf/test_cgroup_attach.c | 108 +++++++++++++++++-
> > 1 file changed, 107 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/test_cgroup_attach.c b/tools/testing/selftests/bpf/test_cgroup_attach.c
> > index 93d4fe295e7d..36441fd0f392 100644
> > --- a/tools/testing/selftests/bpf/test_cgroup_attach.c
> > +++ b/tools/testing/selftests/bpf/test_cgroup_attach.c
> > @@ -456,9 +456,115 @@ static int test_multiprog(void)
> > return rc;
> > }
> >
> > +static int test_autodetach(void)
> > +{
> > + __u32 prog_cnt = 4, attach_flags;
> > + int allow_prog[2] = {0};
> > + __u32 prog_ids[2] = {0};
> > + int cg = 0, i, rc = -1;
> > + void *ptr = NULL;
> > + int attempts;
> > +
> > +
> > + for (i = 0; i < ARRAY_SIZE(allow_prog); i++) {
> > + allow_prog[i] = prog_load_cnt(1, 1 << i);
> > + if (!allow_prog[i])
> > + goto err;
> > + }
> > +
> > + if (setup_cgroup_environment())
> > + goto err;
> > +
> > + /* create a cgroup, attach two programs and remember their ids */
> > + cg = create_and_get_cgroup("/cg_autodetach");
> > + if (cg < 0)
> > + goto err;
> > +
> > + if (join_cgroup("/cg_autodetach"))
> > + goto err;
> > +
> > + for (i = 0; i < ARRAY_SIZE(allow_prog); i++) {
> > + if (bpf_prog_attach(allow_prog[i], cg, BPF_CGROUP_INET_EGRESS,
> > + BPF_F_ALLOW_MULTI)) {
> > + log_err("Attaching prog[%d] to cg:egress", i);
> > + goto err;
> > + }
> > + }
> > +
> > + /* make sure that programs are attached and run some traffic */
> > + assert(bpf_prog_query(cg, BPF_CGROUP_INET_EGRESS, 0, &attach_flags,
> > + prog_ids, &prog_cnt) == 0);
> > + assert(system(PING_CMD) == 0);
> > +
> > + /* allocate some memory (4Mb) to pin the original cgroup */
> > + ptr = malloc(4 * (1 << 20));
> > + if (!ptr)
> > + goto err;
> > +
> > + /* close programs and cgroup fd */
> > + for (i = 0; i < ARRAY_SIZE(allow_prog); i++) {
> > + close(allow_prog[i]);
> > + allow_prog[i] = 0;
> > + }
> > +
> > + close(cg);
> > + cg = 0;
> > +
> > + /* leave the cgroup and remove it. don't detach programs */
> > + cleanup_cgroup_environment();
> > +
>
> [..]
> > + /* programs must stay pinned by the allocated memory */
> > + for (i = 0; i < ARRAY_SIZE(prog_ids); i++) {
> > + int fd = bpf_prog_get_fd_by_id(prog_ids[i]);
> > +
> > + if (fd < 0)
> > + goto err;
> > + close(fd);
> > + }
> This looks a bit flaky. It's essentially the same check you later
> do in a for loop. I guess there is a chance that async auto-detach
> might happen right after cleanup_cgroup_environment and before this for loop?
Ah, this section remained from an earlier version which had another step.
I'll remove it completely, it's totally useless now.
Thanks!
