selftests/xsk: add test when some packets are XDP_DROPed

Add a new test where some of the packets are not passed to the AF_XDP
socket and instead get a XDP_DROP verdict. This is important as it
tests the recycling mechanism of the buffer pool. If a packet is not
sent to the AF_XDP socket, the buffer the packet resides in is instead
recycled so it can be used again without the round-trip to user
space. The test introduces a new XDP program that drops every other
packet.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20230111093526.11682-13-magnus.karlsson@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
index 6981768..744a01d 100644 (file)
--- a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
+++ b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c
@@ -11,9 +11,20 @@ struct {
        __uint(value_size, sizeof(int));
 } xsk SEC(".maps");
 
+static unsigned int idx;
+
 SEC("xdp") int xsk_def_prog(struct xdp_md *xdp)
 {
        return bpf_redirect_map(&xsk, 0, XDP_DROP);
 }
 
+SEC("xdp") int xsk_xdp_drop(struct xdp_md *xdp)
+{
+       /* Drop every other packet */
+       if (idx++ % 2)
+               return XDP_DROP;
+
+       return bpf_redirect_map(&xsk, 0, XDP_DROP);
+}
+
 char _license[] SEC("license") = "GPL";

diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c
index d691002..a33f11b 100644 (file)
--- a/tools/testing/selftests/bpf/xskxceiver.c
+++ b/tools/testing/selftests/bpf/xskxceiver.c
@@ -1646,6 +1646,34 @@ static void testapp_invalid_desc(struct test_spec *test)
        pkt_stream_restore_default(test);
 }
 
+static void testapp_xdp_drop(struct test_spec *test)
+{
+       struct ifobject *ifobj = test->ifobj_rx;
+       int err;
+
+       test_spec_set_name(test, "XDP_DROP_HALF");
+       xsk_detach_xdp_program(ifobj->ifindex, ifobj->xdp_flags);
+       err = xsk_attach_xdp_program(ifobj->xdp_progs->progs.xsk_xdp_drop, ifobj->ifindex,
+                                    ifobj->xdp_flags);
+       if (err) {
+               printf("Error attaching XDP_DROP program\n");
+               test->fail = true;
+               return;
+       }
+
+       pkt_stream_receive_half(test);
+       testapp_validate_traffic(test);
+
+       pkt_stream_restore_default(test);
+       xsk_detach_xdp_program(ifobj->ifindex, ifobj->xdp_flags);
+       err = xsk_attach_xdp_program(ifobj->xdp_progs->progs.xsk_def_prog, ifobj->ifindex,
+                                    ifobj->xdp_flags);
+       if (err) {
+               printf("Error restoring default XDP program\n");
+               exit_with_error(-err);
+       }
+}
+
 static int xsk_load_xdp_programs(struct ifobject *ifobj)
 {
        ifobj->xdp_progs = xsk_xdp_progs__open_and_load();
@@ -1796,6 +1824,9 @@ static void run_pkt_test(struct test_spec *test, enum test_mode mode, enum test_
        case TEST_TYPE_HEADROOM:
                testapp_headroom(test);
                break;
+       case TEST_TYPE_XDP_DROP_HALF:
+               testapp_xdp_drop(test);
+               break;
        default:
                break;
        }

diff --git a/tools/testing/selftests/bpf/xskxceiver.h b/tools/testing/selftests/bpf/xskxceiver.h
index 70b3e5d..a4daa51 100644 (file)
--- a/tools/testing/selftests/bpf/xskxceiver.h
+++ b/tools/testing/selftests/bpf/xskxceiver.h
@@ -87,6 +87,7 @@ enum test_type {
        TEST_TYPE_STATS_RX_FULL,
        TEST_TYPE_STATS_FILL_EMPTY,
        TEST_TYPE_BPF_RES,
+       TEST_TYPE_XDP_DROP_HALF,
        TEST_TYPE_MAX
 };