On 2/4/22 9:52 AM, Lorenzo Bianconi wrote:
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;
The maximum packet size limit 64KB won't change anytime soon.
So the above should work. Some comments to explain why using
the above formula will be good.
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);
}
