Re: [PATCH bpf-next v3 2/5] selftests/bpf: xsk selftests - SKB POLL, NOPOLL

On Fri, 27 Nov 2020 at 04:31, Yonghong Song [off-list ref] wrote:

On 11/25/20 10:37 AM, Weqaar Janjua wrote:

quoted

Adds following tests:

1. AF_XDP SKB mode
    Generic mode XDP is driver independent, used when the driver does
    not have support for XDP. Works on any netdevice using sockets and
    generic XDP path. XDP hook from netif_receive_skb().
    a. nopoll - soft-irq processing
    b. poll - using poll() syscall

Signed-off-by: Weqaar Janjua <redacted>
---
  tools/testing/selftests/bpf/Makefile     |   2 +-
  tools/testing/selftests/bpf/test_xsk.sh  |  36 +-
  tools/testing/selftests/bpf/xdpxceiver.c | 961 +++++++++++++++++++++++
  tools/testing/selftests/bpf/xdpxceiver.h | 151 ++++
  tools/testing/selftests/bpf/xsk_env.sh   |  17 +
  5 files changed, 1158 insertions(+), 9 deletions(-)
  create mode 100644 tools/testing/selftests/bpf/xdpxceiver.c
  create mode 100644 tools/testing/selftests/bpf/xdpxceiver.h

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 596ee5c27906..a2be2725be11 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile

@@ -83,7 +83,7 @@ TEST_PROGS_EXTENDED := with_addr.sh \
  # Compile but not part of 'make run_tests'
  TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
      flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
-     test_lirc_mode2_user xdping test_cpp runqslower bench
+     test_lirc_mode2_user xdping test_cpp runqslower bench xdpxceiver

  TEST_CUSTOM_PROGS = urandom_read

[...]

quoted

+
+static void parse_command_line(int argc, char **argv)
+{
+     int option_index, interface_index = 0, c;
+
+     opterr = 0;
+
+     for (;;) {
+             c = getopt_long(argc, argv, "i:q:pScDC:", long_options, &option_index);
+
+             if (c == -1)
+                     break;
+
+             switch (c) {
+             case 'i':
+                     if (interface_index == MAX_INTERFACES)
+                             break;
+                     char *sptr, *token;
+
+                     memcpy(ifdict[interface_index]->ifname,
+                            strtok_r(optarg, ",", &sptr), MAX_INTERFACE_NAME_CHARS);

During compilation, I hit the following compiler warnings,

xdpxceiver.c: In function ‘main’:
xdpxceiver.c:461:4: warning: ‘__s’ may be used uninitialized in this
function [-Wmaybe-uninitialized]
     memcpy(ifdict[interface_index]->ifname,
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            strtok_r(optarg, ",", &sptr), MAX_INTERFACE_NAME_CHARS);
            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
xdpxceiver.c:443:13: note: ‘__s’ was declared here
  static void parse_command_line(int argc, char **argv)
              ^~~~~~~~~~~~~~~~~~

I am using gcc8. I am not sure whether we should silence such
warning or not (-Wno-maybe-uninitialized). Did you see such a warning
during your compilation?

Most probably you have hit gcc bug 71701, we do not see this warning
as our gcc builds might be different even though mine is 8, I will try
to get rid of strtok_r to avoid the whole thing.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71701

quoted

+                     token = strtok_r(NULL, ",", &sptr);
+                     if (token)
+                             memcpy(ifdict[interface_index]->nsname, token,
+                                    MAX_INTERFACES_NAMESPACE_CHARS);
+                     interface_index++;
+                     break;
+             case 'q':
+                     opt_queue = atoi(optarg);
+                     break;
+             case 'p':
+                     opt_poll = 1;
+                     break;
+             case 'S':
+                     opt_xdp_flags |= XDP_FLAGS_SKB_MODE;
+                     opt_xdp_bind_flags |= XDP_COPY;
+                     uut = ORDER_CONTENT_VALIDATE_XDP_SKB;
+                     break;
+             case 'c':
+                     opt_xdp_bind_flags |= XDP_COPY;
+                     break;
+             case 'D':
+                     debug_pkt_dump = 1;
+                     break;
+             case 'C':
+                     opt_pkt_count = atoi(optarg);
+                     break;
+             default:
+                     usage(basename(argv[0]));
+                     ksft_exit_xfail();
+             }
+     }
+
+     if (!validate_interfaces()) {
+             usage(basename(argv[0]));
+             ksft_exit_xfail();
+     }
+}
+

[...]