diff mbox series

[bpf-next,V7,8/8] bpf/selftests: activating bpf_check_mtu BPF-helper

Message ID 160588912738.2817268.9380466634324530673.stgit@firesoul
State Superseded
Headers show
Series [bpf-next,V7,1/8] bpf: Remove MTU check in __bpf_skb_max_len | expand

Commit Message

Jesper Dangaard Brouer Nov. 20, 2020, 4:18 p.m. UTC 
Adding selftest for BPF-helper bpf_check_mtu(). Making sure
it can be used from both XDP and TC.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 tools/testing/selftests/bpf/prog_tests/check_mtu.c |   37 ++++++++++++++++++++
 tools/testing/selftests/bpf/progs/test_check_mtu.c |   33 ++++++++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c

Comments

Alexei Starovoitov Nov. 20, 2020, 9:50 p.m. UTC | #1 
On Fri, Nov 20, 2020 at 05:18:47PM +0100, Jesper Dangaard Brouer wrote:
> Adding selftest for BPF-helper bpf_check_mtu(). Making sure
> it can be used from both XDP and TC.
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> ---
>  tools/testing/selftests/bpf/prog_tests/check_mtu.c |   37 ++++++++++++++++++++
>  tools/testing/selftests/bpf/progs/test_check_mtu.c |   33 ++++++++++++++++++
>  2 files changed, 70 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> new file mode 100644
> index 000000000000..09b8f986a17b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <uapi/linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <test_progs.h>
> +
> +#include "test_check_mtu.skel.h"
> +#define IFINDEX_LO 1
> +
> +void test_check_mtu_xdp(struct test_check_mtu *skel)
> +{
> +	int err = 0;
> +	int fd;
> +
> +	fd = bpf_program__fd(skel->progs.xdp_use_helper);
> +	err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
> +	if (CHECK_FAIL(err))
> +		return;
> +
> +	bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
> +}
> +
> +void test_check_mtu(void)
> +{
> +	struct test_check_mtu *skel;
> +
> +	skel = test_check_mtu__open_and_load();
> +	if (CHECK_FAIL(!skel)) {
> +		perror("test_check_mtu__open_and_load");
> +		return;
> +	}
> +
> +	if (test__start_subtest("bpf_check_mtu XDP-attach"))
> +		test_check_mtu_xdp(skel);
> +
> +	test_check_mtu__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> new file mode 100644
> index 000000000000..ab97ec925a32
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> @@ -0,0 +1,33 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("xdp")
> +int xdp_use_helper(struct xdp_md *ctx)
> +{
> +	uint32_t mtu_len = 0;
> +	int delta = 20;
> +
> +	if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> +		return XDP_ABORTED;
> +	}
> +	return XDP_PASS;
> +}
> +
> +SEC("classifier")
> +int tc_use_helper(struct __sk_buff *ctx)
> +{
> +	uint32_t mtu_len = 0;
> +	int delta = -20;
> +
> +	if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> +		return BPF_DROP;
> +	}
> +	return BPF_OK;
> +}

Patches 7 and 8 are not adequate as tests.
They do not testing the functionality of earlier patches.
bpf_check_mtu() could be returning random value and "tests" 7 and 8 would still pass.
Please fix.
Andrii Nakryiko Nov. 21, 2020, 7:41 a.m. UTC | #2 
On Fri, Nov 20, 2020 at 8:21 AM Jesper Dangaard Brouer
<brouer@redhat.com> wrote:
>
> Adding selftest for BPF-helper bpf_check_mtu(). Making sure
> it can be used from both XDP and TC.
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> ---
>  tools/testing/selftests/bpf/prog_tests/check_mtu.c |   37 ++++++++++++++++++++
>  tools/testing/selftests/bpf/progs/test_check_mtu.c |   33 ++++++++++++++++++
>  2 files changed, 70 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> new file mode 100644
> index 000000000000..09b8f986a17b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <uapi/linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <test_progs.h>
> +
> +#include "test_check_mtu.skel.h"
> +#define IFINDEX_LO 1
> +
> +void test_check_mtu_xdp(struct test_check_mtu *skel)

this should be static func, otherwise it's treated as an independent selftest.

> +{
> +       int err = 0;
> +       int fd;
> +
> +       fd = bpf_program__fd(skel->progs.xdp_use_helper);
> +       err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
> +       if (CHECK_FAIL(err))

please use CHECK() or one of ASSERT_xxx() helpers. CHECK_FAIL() should
be used for high-volume unlikely to fail test (i.e., very rarely).

> +               return;
> +
> +       bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
> +}
> +
> +void test_check_mtu(void)
> +{
> +       struct test_check_mtu *skel;
> +
> +       skel = test_check_mtu__open_and_load();
> +       if (CHECK_FAIL(!skel)) {
> +               perror("test_check_mtu__open_and_load");
> +               return;
> +       }
> +
> +       if (test__start_subtest("bpf_check_mtu XDP-attach"))
> +               test_check_mtu_xdp(skel);
> +
> +       test_check_mtu__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> new file mode 100644
> index 000000000000..ab97ec925a32
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
> @@ -0,0 +1,33 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Red Hat */
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("xdp")
> +int xdp_use_helper(struct xdp_md *ctx)
> +{
> +       uint32_t mtu_len = 0;
> +       int delta = 20;
> +
> +       if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> +               return XDP_ABORTED;
> +       }

nit: unnecessary {} for single-line if; same below

> +       return XDP_PASS;
> +}
> +
> +SEC("classifier")
> +int tc_use_helper(struct __sk_buff *ctx)
> +{
> +       uint32_t mtu_len = 0;
> +       int delta = -20;
> +
> +       if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
> +               return BPF_DROP;
> +       }
> +       return BPF_OK;
> +}
>
>
Jesper Dangaard Brouer Nov. 24, 2020, 2:33 p.m. UTC | #3 
On Fri, 20 Nov 2020 23:41:11 -0800
Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:

> On Fri, Nov 20, 2020 at 8:21 AM Jesper Dangaard Brouer
> <brouer@redhat.com> wrote:
> >
> > Adding selftest for BPF-helper bpf_check_mtu(). Making sure
> > it can be used from both XDP and TC.
> >
> > Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> > ---
> >  tools/testing/selftests/bpf/prog_tests/check_mtu.c |   37 ++++++++++++++++++++
> >  tools/testing/selftests/bpf/progs/test_check_mtu.c |   33 ++++++++++++++++++
> >  2 files changed, 70 insertions(+)
> >  create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
> >  create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> > new file mode 100644
> > index 000000000000..09b8f986a17b
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
> > @@ -0,0 +1,37 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2020 Red Hat */
> > +#include <uapi/linux/bpf.h>
> > +#include <linux/if_link.h>
> > +#include <test_progs.h>
> > +
> > +#include "test_check_mtu.skel.h"
> > +#define IFINDEX_LO 1
> > +
> > +void test_check_mtu_xdp(struct test_check_mtu *skel)  
> 
> this should be static func, otherwise it's treated as an independent selftest.

Ok, fixed.

> > +{
> > +       int err = 0;
> > +       int fd;
> > +
> > +       fd = bpf_program__fd(skel->progs.xdp_use_helper);
> > +       err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
> > +       if (CHECK_FAIL(err))  
> 
> please use CHECK() or one of ASSERT_xxx() helpers. CHECK_FAIL() should
> be used for high-volume unlikely to fail test (i.e., very rarely).

I could not get CHECK() macro working.  I now realize that this is
because I've not defined a global static variable named 'duration'.

 static __u32 duration;

I wonder, are there any best-practice documentation or blogpost on
howto write these bpf-selftests?


Below signature is the compile error for others to Google for, and
solution above.
- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer


$ make
  TEST-OBJ [test_progs] check_mtu.test.o
In file included from /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:6:
/home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c: In function ‘test_check_mtu’:
./test_progs.h:129:25: error: ‘duration’ undeclared (first use in this function)
  129 |  _CHECK(condition, tag, duration, format)
      |                         ^~~~~~~~
./test_progs.h:111:25: note: in definition of macro ‘_CHECK’
  111 |          __func__, tag, duration);   \
      |                         ^~~~~~~~
/home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:33:6: note: in expansion of macro ‘CHECK’
   33 |  if (CHECK(!skel, "open and load skel", "failed"))
      |      ^~~~~
./test_progs.h:129:25: note: each undeclared identifier is reported only once for each function it appears in
  129 |  _CHECK(condition, tag, duration, format)
      |                         ^~~~~~~~
./test_progs.h:111:25: note: in definition of macro ‘_CHECK’
  111 |          __func__, tag, duration);   \
      |                         ^~~~~~~~
/home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:33:6: note: in expansion of macro ‘CHECK’
   33 |  if (CHECK(!skel, "open and load skel", "failed"))
      |      ^~~~~
make: *** [Makefile:396: /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/check_mtu.test.o] Error 1
Yonghong Song Nov. 24, 2020, 4:50 p.m. UTC | #4 
On 11/24/20 6:33 AM, Jesper Dangaard Brouer wrote:
> On Fri, 20 Nov 2020 23:41:11 -0800
> Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
> 
>> On Fri, Nov 20, 2020 at 8:21 AM Jesper Dangaard Brouer
>> <brouer@redhat.com> wrote:
>>>
>>> Adding selftest for BPF-helper bpf_check_mtu(). Making sure
>>> it can be used from both XDP and TC.
>>>
>>> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
>>> ---
>>>   tools/testing/selftests/bpf/prog_tests/check_mtu.c |   37 ++++++++++++++++++++
>>>   tools/testing/selftests/bpf/progs/test_check_mtu.c |   33 ++++++++++++++++++
>>>   2 files changed, 70 insertions(+)
>>>   create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c
>>>   create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c
>>>
>>> diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
>>> new file mode 100644
>>> index 000000000000..09b8f986a17b
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
>>> @@ -0,0 +1,37 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/* Copyright (c) 2020 Red Hat */
>>> +#include <uapi/linux/bpf.h>
>>> +#include <linux/if_link.h>
>>> +#include <test_progs.h>
>>> +
>>> +#include "test_check_mtu.skel.h"
>>> +#define IFINDEX_LO 1
>>> +
>>> +void test_check_mtu_xdp(struct test_check_mtu *skel)
>>
>> this should be static func, otherwise it's treated as an independent selftest.
> 
> Ok, fixed.
> 
>>> +{
>>> +       int err = 0;
>>> +       int fd;
>>> +
>>> +       fd = bpf_program__fd(skel->progs.xdp_use_helper);
>>> +       err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
>>> +       if (CHECK_FAIL(err))
>>
>> please use CHECK() or one of ASSERT_xxx() helpers. CHECK_FAIL() should
>> be used for high-volume unlikely to fail test (i.e., very rarely).
> 
> I could not get CHECK() macro working.  I now realize that this is
> because I've not defined a global static variable named 'duration'.
> 
>   static __u32 duration;
> 
> I wonder, are there any best-practice documentation or blogpost on
> howto write these bpf-selftests?

The 'duration' in old days is used to measure performance. Today most
of selftests actually do not need this. We do not have doc/blogpost
for this. The best is to look at other files under prog_tests to see
how they handle duration ...

> 
> 
> Below signature is the compile error for others to Google for, and
> solution above.
> -
> Best regards,
>    Jesper Dangaard Brouer
>    MSc.CS, Principal Kernel Engineer at Red Hat
>    LinkedIn: http://www.linkedin.com/in/brouer
> 
> 
> $ make
>    TEST-OBJ [test_progs] check_mtu.test.o
> In file included from /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:6:
> /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c: In function ‘test_check_mtu’:
> ./test_progs.h:129:25: error: ‘duration’ undeclared (first use in this function)
>    129 |  _CHECK(condition, tag, duration, format)
>        |                         ^~~~~~~~
> ./test_progs.h:111:25: note: in definition of macro ‘_CHECK’
>    111 |          __func__, tag, duration);   \
>        |                         ^~~~~~~~
> /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:33:6: note: in expansion of macro ‘CHECK’
>     33 |  if (CHECK(!skel, "open and load skel", "failed"))
>        |      ^~~~~
> ./test_progs.h:129:25: note: each undeclared identifier is reported only once for each function it appears in
>    129 |  _CHECK(condition, tag, duration, format)
>        |                         ^~~~~~~~
> ./test_progs.h:111:25: note: in definition of macro ‘_CHECK’
>    111 |          __func__, tag, duration);   \
>        |                         ^~~~~~~~
> /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/prog_tests/check_mtu.c:33:6: note: in expansion of macro ‘CHECK’
>     33 |  if (CHECK(!skel, "open and load skel", "failed"))
>        |      ^~~~~
> make: *** [Makefile:396: /home/jbrouer/git/kernel/bpf-next/tools/testing/selftests/bpf/check_mtu.test.o] Error 1
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
new file mode 100644
index 000000000000..09b8f986a17b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
@@ -0,0 +1,37 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Red Hat */
+#include <uapi/linux/bpf.h>
+#include <linux/if_link.h>
+#include <test_progs.h>
+
+#include "test_check_mtu.skel.h"
+#define IFINDEX_LO 1
+
+void test_check_mtu_xdp(struct test_check_mtu *skel)
+{
+	int err = 0;
+	int fd;
+
+	fd = bpf_program__fd(skel->progs.xdp_use_helper);
+	err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE);
+	if (CHECK_FAIL(err))
+		return;
+
+	bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0);
+}
+
+void test_check_mtu(void)
+{
+	struct test_check_mtu *skel;
+
+	skel = test_check_mtu__open_and_load();
+	if (CHECK_FAIL(!skel)) {
+		perror("test_check_mtu__open_and_load");
+		return;
+	}
+
+	if (test__start_subtest("bpf_check_mtu XDP-attach"))
+		test_check_mtu_xdp(skel);
+
+	test_check_mtu__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
new file mode 100644
index 000000000000..ab97ec925a32
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
@@ -0,0 +1,33 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Red Hat */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("xdp")
+int xdp_use_helper(struct xdp_md *ctx)
+{
+	uint32_t mtu_len = 0;
+	int delta = 20;
+
+	if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
+		return XDP_ABORTED;
+	}
+	return XDP_PASS;
+}
+
+SEC("classifier")
+int tc_use_helper(struct __sk_buff *ctx)
+{
+	uint32_t mtu_len = 0;
+	int delta = -20;
+
+	if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) {
+		return BPF_DROP;
+	}
+	return BPF_OK;
+}