On Fri, 20 Nov 2020 23:41:11 -0800
Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
> On Fri, Nov 20, 2020 at 8:21 AM Jesper Dangaard Brouer
> <brouer@xxxxxxxxxx> 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@xxxxxxxxxx>
> > ---
> > 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
