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Message-ID: <CAJ8uoz0HcfG-mkmEEPifmq9_4puBymbk=Yw6jU6XUrRgGrWPXA@mail.gmail.com>
Date: Wed, 14 Dec 2022 11:53:04 +0100
From: Magnus Karlsson <magnus.karlsson@...il.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc: magnus.karlsson@...el.com, bjorn@...nel.org, ast@...nel.org,
daniel@...earbox.net, netdev@...r.kernel.org, bpf@...r.kernel.org,
yhs@...com, andrii@...nel.org, martin.lau@...ux.dev,
song@...nel.org, john.fastabend@...il.com, kpsingh@...nel.org,
sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org,
jonathan.lemon@...il.com
Subject: Re: [PATCH bpf-next 12/15] selftests/xsk: add test when some packets
are XDP_DROPed
On Mon, Dec 12, 2022 at 4:14 PM Maciej Fijalkowski
<maciej.fijalkowski@...el.com> wrote:
>
> On Tue, Dec 06, 2022 at 10:08:23AM +0100, Magnus Karlsson wrote:
> > From: Magnus Karlsson <magnus.karlsson@...el.com>
> >
> > 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@...el.com>
> > ---
> > tools/testing/selftests/bpf/Makefile | 2 +-
> > .../selftests/bpf/progs/xsk_xdp_drop.c | 25 ++++++++++
> > tools/testing/selftests/bpf/xskxceiver.c | 48 +++++++++++++++++--
> > tools/testing/selftests/bpf/xskxceiver.h | 3 ++
> > 4 files changed, 72 insertions(+), 6 deletions(-)
> > create mode 100644 tools/testing/selftests/bpf/progs/xsk_xdp_drop.c
> >
> > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > index 42e15b5a34a7..77ef8a8e6db4 100644
> > --- a/tools/testing/selftests/bpf/Makefile
> > +++ b/tools/testing/selftests/bpf/Makefile
> > @@ -240,7 +240,7 @@ $(OUTPUT)/flow_dissector_load: $(TESTING_HELPERS)
> > $(OUTPUT)/test_maps: $(TESTING_HELPERS)
> > $(OUTPUT)/test_verifier: $(TESTING_HELPERS) $(CAP_HELPERS)
> > $(OUTPUT)/xsk.o: $(BPFOBJ)
> > -$(OUTPUT)/xskxceiver: $(OUTPUT)/xsk.o $(OUTPUT)/xsk_def_prog.skel.h
> > +$(OUTPUT)/xskxceiver: $(OUTPUT)/xsk.o $(OUTPUT)/xsk_def_prog.skel.h $(OUTPUT)/xsk_xdp_drop.skel.h
> >
> > BPFTOOL ?= $(DEFAULT_BPFTOOL)
> > $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) \
> > diff --git a/tools/testing/selftests/bpf/progs/xsk_xdp_drop.c b/tools/testing/selftests/bpf/progs/xsk_xdp_drop.c
> > new file mode 100644
> > index 000000000000..12a12b0d9fc1
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/xsk_xdp_drop.c
> > @@ -0,0 +1,25 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2022 Intel */
> > +
> > +#include <linux/bpf.h>
> > +#include <bpf/bpf_helpers.h>
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_XSKMAP);
> > + __uint(max_entries, 1);
> > + __uint(key_size, sizeof(int));
> > + __uint(value_size, sizeof(int));
> > +} xsk SEC(".maps");
> > +
> > +static unsigned int idx;
> > +
> > +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 0cda4e3f1871..522dc1d69c17 100644
> > --- a/tools/testing/selftests/bpf/xskxceiver.c
> > +++ b/tools/testing/selftests/bpf/xskxceiver.c
> > @@ -1654,18 +1654,53 @@ static void testapp_invalid_desc(struct test_spec *test)
> > pkt_stream_restore_default(test);
> > }
> >
> > -static int xsk_load_xdp_program(struct ifobject *ifobj)
> > +static void testapp_xdp_drop(struct test_spec *test)
> > +{
> > + struct ifobject *ifobj = test->ifobj_rx;
> > + int err;
> > +
> > + test_spec_set_name(test, "XDP_CONSUMES_SOME_PACKETS");
>
> XDP_DROP_ODD_PACKETS ?
Ha! What is an ODD packet?!?! I will think of a better name than these two.
> > + xsk_detach_xdp_program(ifobj->ifindex, ifobj->xdp_flags);
> > + err = xsk_attach_xdp_program(ifobj->xdp_drop->progs.xsk_xdp_drop, ifobj->ifindex,
> > + ifobj->xdp_flags);
> > + if (err) {
> > + printf("Error attaching XDP_DROP program\n");
> > + test->fail = true;
> > + return;
> > + }
> > + ifobj->xskmap = ifobj->xdp_drop->maps.xsk;
> > +
> > + 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->def_prog->progs.xsk_def_prog, ifobj->ifindex,
> > + ifobj->xdp_flags);
> > + if (err) {
> > + printf("Error restoring default XDP program\n");
> > + exit_with_error(-err);
> > + }
> > + ifobj->xskmap = ifobj->def_prog->maps.xsk;
> > +}
> > +
> > +static int xsk_load_xdp_programs(struct ifobject *ifobj)
> > {
> > ifobj->def_prog = xsk_def_prog__open_and_load();
> > if (libbpf_get_error(ifobj->def_prog))
> > return libbpf_get_error(ifobj->def_prog);
> >
> > + ifobj->xdp_drop = xsk_xdp_drop__open_and_load();
> > + if (libbpf_get_error(ifobj->xdp_drop))
> > + return libbpf_get_error(ifobj->xdp_drop);
> > +
> > return 0;
> > }
> >
> > -static void xsk_unload_xdp_program(struct ifobject *ifobj)
> > +static void xsk_unload_xdp_programs(struct ifobject *ifobj)
> > {
> > xsk_def_prog__destroy(ifobj->def_prog);
> > + xsk_xdp_drop__destroy(ifobj->xdp_drop);
> > }
> >
> > static void init_iface(struct ifobject *ifobj, const char *dst_mac, const char *src_mac,
> > @@ -1692,7 +1727,7 @@ static void init_iface(struct ifobject *ifobj, const char *dst_mac, const char *
> > if (!load_xdp)
> > return;
> >
> > - err = xsk_load_xdp_program(ifobj);
> > + err = xsk_load_xdp_programs(ifobj);
> > if (err) {
> > printf("Error loading XDP program\n");
> > exit_with_error(err);
> > @@ -1804,6 +1839,9 @@ 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_CONSUMES_PACKETS:
> > + testapp_xdp_drop(test);
> > + break;
> > default:
> > break;
> > }
> > @@ -1971,8 +2009,8 @@ int main(int argc, char **argv)
> >
> > pkt_stream_delete(tx_pkt_stream_default);
> > pkt_stream_delete(rx_pkt_stream_default);
> > - xsk_unload_xdp_program(ifobj_tx);
> > - xsk_unload_xdp_program(ifobj_rx);
> > + xsk_unload_xdp_programs(ifobj_tx);
> > + xsk_unload_xdp_programs(ifobj_rx);
> > ifobject_delete(ifobj_tx);
> > ifobject_delete(ifobj_rx);
> >
> > diff --git a/tools/testing/selftests/bpf/xskxceiver.h b/tools/testing/selftests/bpf/xskxceiver.h
> > index eb6355bcc143..3483ac240b2e 100644
> > --- a/tools/testing/selftests/bpf/xskxceiver.h
> > +++ b/tools/testing/selftests/bpf/xskxceiver.h
> > @@ -6,6 +6,7 @@
> > #define XSKXCEIVER_H_
> >
> > #include "xsk_def_prog.skel.h"
> > +#include "xsk_xdp_drop.skel.h"
> >
> > #ifndef SOL_XDP
> > #define SOL_XDP 283
> > @@ -87,6 +88,7 @@ enum test_type {
> > TEST_TYPE_STATS_RX_FULL,
> > TEST_TYPE_STATS_FILL_EMPTY,
> > TEST_TYPE_BPF_RES,
> > + TEST_TYPE_XDP_CONSUMES_PACKETS,
> > TEST_TYPE_MAX
> > };
> >
> > @@ -141,6 +143,7 @@ struct ifobject {
> > validation_func_t validation_func;
> > struct pkt_stream *pkt_stream;
> > struct xsk_def_prog *def_prog;
> > + struct xsk_xdp_drop *xdp_drop;
>
> Is this going to scale if we add plenty of XDP progs for testing?
Good point. No. I will put the programs in the same source file and
see if that makes it better.
> > struct bpf_map *xskmap;
> > int ifindex;
> > u32 dst_ip;
> > --
> > 2.34.1
> >
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