>
>
> On 2/4/22 5:58 AM, Lorenzo Bianconi wrote:
> > Update test_xdp_update_frags adding a test for a buffer size
> > set to (MAX_SKB_FRAGS + 2) * PAGE_SIZE. The kernel is supposed
> > to return -ENOMEM.
> >
> > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> > ---
> > .../bpf/prog_tests/xdp_adjust_frags.c | 37 ++++++++++++++++++-
> > 1 file changed, 36 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> > index 134d0ac32f59..61d5b585eb15 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> > @@ -5,11 +5,12 @@
> > void test_xdp_update_frags(void)
> > {
> > const char *file = "./test_xdp_update_frags.o";
> > + int err, prog_fd, max_skb_frags, buf_size, num;
> > struct bpf_program *prog;
> > struct bpf_object *obj;
> > - int err, prog_fd;
> > __u32 *offset;
> > __u8 *buf;
> > + FILE *f;
> > LIBBPF_OPTS(bpf_test_run_opts, topts);
> > obj = bpf_object__open(file);
> > @@ -99,6 +100,40 @@ void test_xdp_update_frags(void)
> > ASSERT_EQ(buf[7621], 0xbb, "xdp_update_frag buf[7621]");
> > free(buf);
> > +
> > + /* test_xdp_update_frags: unsupported buffer size */
> > + f = fopen("/proc/sys/net/core/max_skb_frags", "r");
> > + if (!ASSERT_OK_PTR(f, "max_skb_frag file pointer"))
> > + goto out;
>
> In kernel, the nr_frags checking is against MAX_SKB_FRAGS,
> but if /proc/sys/net/core/max_skb_flags is 2 or more less
> than MAX_SKB_FRAGS, the test won't fail, right?
yes, you are right. Should we use the same definition used in
include/linux/skbuff.h instead? Something like:
if (65536 / page_size + 1 < 16)
max_skb_flags = 16;
else
max_skb_flags = 65536/page_size + 1;
Regards,
Lorenzo
>
> > +
> > + num = fscanf(f, "%d", &max_skb_frags);
> > + fclose(f);
> > +
> > + if (!ASSERT_EQ(num, 1, "max_skb_frags read failed"))
> > + goto out;
> > +
> > + /* xdp_buff linear area size is always set to 4096 in the
> > + * bpf_prog_test_run_xdp routine.
> > + */
> > + buf_size = 4096 + (max_skb_frags + 1) * sysconf(_SC_PAGE_SIZE);
> > + buf = malloc(buf_size);
> > + if (!ASSERT_OK_PTR(buf, "alloc buf"))
> > + goto out;
> > +
> > + memset(buf, 0, buf_size);
> > + offset = (__u32 *)buf;
> > + *offset = 16;
> > + buf[*offset] = 0xaa;
> > + buf[*offset + 15] = 0xaa;
> > +
> > + topts.data_in = buf;
> > + topts.data_out = buf;
> > + topts.data_size_in = buf_size;
> > + topts.data_size_out = buf_size;
> > +
> > + err = bpf_prog_test_run_opts(prog_fd, &topts);
> > + ASSERT_EQ(err, -ENOMEM, "unsupported buffer size");
> > + free(buf);
> > out:
> > bpf_object__close(obj);
> > }
>
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