From: Kui-Feng Lee <sinquersw@gmail.com>
To: Martin KaFai Lau <martin.lau@linux.dev>,
Kui-Feng Lee <thinker.li@gmail.com>
Cc: kuifeng@meta.com, bpf@vger.kernel.org, ast@kernel.org,
song@kernel.org, kernel-team@meta.com, andrii@kernel.org
Subject: Re: [PATCH bpf-next v2 5/6] selftests/bpf: detach a struct_ops link from the subsystem managing it.
Date: Wed, 8 May 2024 22:50:04 -0700 [thread overview]
Message-ID: <d66a62fe-cce8-43fe-86e0-f21d98a8c69e@gmail.com> (raw)
In-Reply-To: <f0f66283-9c11-4fd8-9880-d9bbc6e36b55@linux.dev>
On 5/8/24 16:50, Martin KaFai Lau wrote:
> On 5/6/24 10:55 PM, Kui-Feng Lee wrote:
>> Not only a user space program can detach a struct_ops link, the subsystem
>> managing a link can also detach the link. This patch add a kfunc to
>> simulate detaching a link by the subsystem managing it.
>>
>> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
>> ---
>> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++
>> .../bpf/prog_tests/test_struct_ops_module.c | 65 +++++++++++++++++++
>> .../selftests/bpf/progs/struct_ops_detach.c | 6 ++
>> 3 files changed, 92 insertions(+)
>>
>> diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> index c89a6414c69f..0bf1acc1767a 100644
>> --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
>> @@ -502,6 +502,26 @@ __bpf_kfunc void bpf_kfunc_call_test_sleepable(void)
>> static DEFINE_MUTEX(detach_mutex);
>> static struct bpf_link *link_to_detach;
>> +__bpf_kfunc int bpf_dummy_do_link_detach(void)
>> +{
>> + struct bpf_link *link;
>> + int ret = -ENOENT;
>> +
>> + mutex_lock(&detach_mutex);
>> + link = link_to_detach;
>> + /* Make sure the link is still valid by increasing its refcnt */
>> + if (link && !atomic64_inc_not_zero(&link->refcnt))
>
> It is better to reuse the bpf_link_inc_not_zero().
I will export this function to be used by modules.
>
>> + link = NULL;
>> + mutex_unlock(&detach_mutex);
>> +
>> + if (link) {
>> + ret = link->ops->detach(link);
>> + bpf_link_put(link);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> BTF_KFUNCS_START(bpf_testmod_check_kfunc_ids)
>> BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
>> BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
>> @@ -529,6 +549,7 @@ BTF_ID_FLAGS(func,
>> bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE)
>> BTF_ID_FLAGS(func, bpf_kfunc_call_test_static_unused_arg)
>> BTF_ID_FLAGS(func, bpf_kfunc_call_test_offset)
>> BTF_ID_FLAGS(func, bpf_kfunc_call_test_sleepable, KF_SLEEPABLE)
>> +BTF_ID_FLAGS(func, bpf_dummy_do_link_detach)
>
> It should need KF_SLEEPABLE. mutex is used.
To simplify it, spinlock will be used instead.
>
>> BTF_KFUNCS_END(bpf_testmod_check_kfunc_ids)
>> static int bpf_testmod_ops_init(struct btf *btf)
>> diff --git
>> a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
>> b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
>> index f39455b81664..9f6657b53a93 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
>> @@ -229,6 +229,69 @@ static void test_detach_link(void)
>> struct_ops_detach__destroy(skel);
>> }
>> +/* Detach a link from the subsystem that the link was registered to */
>> +static void test_subsystem_detach(void)
>> +{
>> + LIBBPF_OPTS(bpf_test_run_opts, topts,
>> + .data_in = &pkt_v4,
>> + .data_size_in = sizeof(pkt_v4));
>> + struct epoll_event ev, events[2];
>> + struct struct_ops_detach *skel;
>> + struct bpf_link *link = NULL;
>> + int fd, epollfd = -1, nfds;
>> + int prog_fd;
>> + int err;
>> +
>> + skel = struct_ops_detach__open_and_load();
>> + if (!ASSERT_OK_PTR(skel, "struct_ops_detach_open_and_load"))
>> + return;
>> +
>> + link = bpf_map__attach_struct_ops(skel->maps.testmod_do_detach);
>> + if (!ASSERT_OK_PTR(link, "attach_struct_ops"))
>> + goto cleanup;
>> +
>> + fd = bpf_link__fd(link);
>> + if (!ASSERT_GE(fd, 0, "link_fd"))
>> + goto cleanup;
>> +
>> + prog_fd = bpf_program__fd(skel->progs.start_detach);
>> + if (!ASSERT_GE(prog_fd, 0, "start_detach_fd"))
>> + goto cleanup;
>> +
>> + /* Do detachment from the registered subsystem */
>> + err = bpf_prog_test_run_opts(prog_fd, &topts);
>> + if (!ASSERT_OK(err, "start_detach_run"))
>> + goto cleanup;
>> +
>> + if (!ASSERT_EQ(topts.retval, 0, "start_detach_run retval"))
>> + goto cleanup;
>> +
>> + epollfd = epoll_create1(0);
>> + if (!ASSERT_GE(epollfd, 0, "epoll_create1"))
>> + goto cleanup;
>> +
>> + ev.events = EPOLLHUP;
>> + ev.data.fd = fd;
>> + err = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
>> + if (!ASSERT_OK(err, "epoll_ctl"))
>> + goto cleanup;
>> +
>> + /* Wait for EPOLLHUP */
>> + nfds = epoll_wait(epollfd, events, 2, 5000);
>> + if (!ASSERT_EQ(nfds, 1, "epoll_wait"))
>> + goto cleanup;
>> +
>> + if (!ASSERT_EQ(events[0].data.fd, fd, "epoll_wait_fd"))
>> + goto cleanup;
>> + if (!ASSERT_TRUE(events[0].events & EPOLLHUP, "events[0].events"))
>> + goto cleanup;
>> +
>> +cleanup:
>> + close(epollfd);
>> + bpf_link__destroy(link);
>> + struct_ops_detach__destroy(skel);
>> +}
>> +
>> void serial_test_struct_ops_module(void)
>> {
>> if (test__start_subtest("test_struct_ops_load"))
>> @@ -239,5 +302,7 @@ void serial_test_struct_ops_module(void)
>> test_struct_ops_incompatible();
>> if (test__start_subtest("test_detach_link"))
>> test_detach_link();
>> + if (test__start_subtest("test_subsystem_detach"))
>> + test_subsystem_detach();
>> }
>> diff --git a/tools/testing/selftests/bpf/progs/struct_ops_detach.c
>> b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
>> index aeb355b3bea3..139f9a5c5601 100644
>> --- a/tools/testing/selftests/bpf/progs/struct_ops_detach.c
>> +++ b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
>> @@ -29,3 +29,9 @@ struct bpf_testmod_ops testmod_do_detach = {
>> .test_1 = (void *)test_1,
>> .test_2 = (void *)test_2,
>> };
>> +
>> +SEC("tc")
>
> The bpf_dummy_do_link_detach() uses a mutex. There is no lockdep splat
> in the test?
>
>> +int start_detach(void *skb)
>> +{
>> + return bpf_dummy_do_link_detach();
>> +}
>
next prev parent reply other threads:[~2024-05-09 5:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 5:55 [PATCH bpf-next v2 0/6] Notify user space when a struct_ops object is detached/unregistered Kui-Feng Lee
2024-05-07 5:55 ` [PATCH bpf-next v2 1/6] bpf: pass bpf_struct_ops_link to callbacks in bpf_struct_ops Kui-Feng Lee
2024-05-07 5:55 ` [PATCH bpf-next v2 2/6] bpf: enable detaching links of struct_ops objects Kui-Feng Lee
2024-05-08 23:22 ` Martin KaFai Lau
2024-05-09 0:14 ` Kui-Feng Lee
2024-05-09 0:36 ` Martin KaFai Lau
2024-05-09 16:59 ` Kui-Feng Lee
2024-05-09 0:46 ` Kui-Feng Lee
2024-05-07 5:55 ` [PATCH bpf-next v2 3/6] bpf: support epoll from bpf struct_ops links Kui-Feng Lee
2024-05-07 5:55 ` [PATCH bpf-next v2 4/6] selftests/bpf: test struct_ops with epoll Kui-Feng Lee
2024-05-08 23:34 ` Martin KaFai Lau
2024-05-09 0:22 ` Kui-Feng Lee
2024-05-07 5:55 ` [PATCH bpf-next v2 5/6] selftests/bpf: detach a struct_ops link from the subsystem managing it Kui-Feng Lee
2024-05-08 23:50 ` Martin KaFai Lau
2024-05-09 5:50 ` Kui-Feng Lee [this message]
2024-05-07 5:56 ` [PATCH bpf-next v2 6/6] selftests/bpf: make sure bpf_testmod handling racing link destroying well Kui-Feng Lee
2024-05-09 0:04 ` Martin KaFai Lau
2024-05-09 17:02 ` Kui-Feng Lee
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