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Wed, 22 May 2019 15:24:38 -0700 (PDT) Date: Wed, 22 May 2019 15:24:38 -0700 From: Stanislav Fomichev To: Roman Gushchin Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, Tejun Heo , kernel-team@fb.com, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf-next 4/4] selftests/bpf: add auto-detach test Message-ID: <20190522222438.GB3032@mini-arch> References: <20190522212932.2646247-1-guro@fb.com> <20190522212932.2646247-5-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522212932.2646247-5-guro@fb.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 > --- > .../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? > + > + /* wait for the asynchronous auto-detachment. > + * wait for no more than 5 sec and give up. > + */ > + for (i = 0; i < ARRAY_SIZE(prog_ids); i++) { > + for (attempts = 5; attempts >= 0; attempts--) { > + int fd = bpf_prog_get_fd_by_id(prog_ids[i]); > + > + if (fd < 0) > + break; > + > + /* don't leave the fd open */ > + close(fd); > + > + if (!attempts) > + goto err; > + > + sleep(1); > + } > + } > + > + rc = 0; > +err: > + for (i = 0; i < ARRAY_SIZE(allow_prog); i++) > + if (allow_prog[i] > 0) > + close(allow_prog[i]); > + if (cg) > + close(cg); > + free(ptr); > + cleanup_cgroup_environment(); > + if (!rc) > + printf("#autodetach:PASS\n"); > + else > + printf("#autodetach:FAIL\n"); > + return rc; > +} > + > int main(int argc, char **argv) > { > - int (*tests[])(void) = {test_foo_bar, test_multiprog}; > + int (*tests[])(void) = { > + test_foo_bar, > + test_multiprog, > + test_autodetach, > + }; > int errors = 0; > int i; > > -- > 2.20.1 >