linux-kernel - [PATCH bpf-next v3 3/3] selftests/bpf: check program redirect in xdp_cpumap

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Message-Id: <20241009-convert_xdp_tests-v3-3-51cea913710c@bootlin.com>
Date: Wed, 09 Oct 2024 12:12:09 +0200
From: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, 
 "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
 Jesper Dangaard Brouer <hawk@...nel.org>, 
 John Fastabend <john.fastabend@...il.com>, 
 Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, 
 Shuah Khan <shuah@...nel.org>
Cc: ebpf@...uxfoundation.org, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, netdev@...r.kernel.org, 
 bpf@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
Subject: [PATCH bpf-next v3 3/3] selftests/bpf: check program redirect in
 xdp_cpumap_attach

xdp_cpumap_attach, in its current form, only checks that an xdp cpumap
program can be executed, but not that it performs correctly the cpu
redirect as configured by userspace (bpf_prog_test_run_opts will return
success even if the redirect program returns an error)

Add a check to ensure that the program performs the configured redirect
as well. The check is based on a global variable incremented by a
chained program executed only if the redirect program properly executes.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
---
Changes in v3:
- new patch
---
 tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c     | 10 ++++++++--
 .../testing/selftests/bpf/progs/test_xdp_with_cpumap_helpers.c |  5 +++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c
index 31c225f0239613f6b5adad36b5b0e6e85eeddd9a..57d1661dc72aeb152c7cb9c2f63e3b47bf1799d8 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c
@@ -62,8 +62,11 @@ static void test_xdp_with_cpumap_helpers(void)
 	err = bpf_prog_test_run_opts(prog_redir_fd, &opts);
 	ASSERT_OK(err, "XDP test run");

-	/* wait for the packets to be flushed */
+	/* wait for the packets to be flushed, then check that redirect has been
+	 * performed
+	 */
 	kern_sync_rcu();
+	ASSERT_NEQ(skel->bss->redirect_count, 0, "redirected packets");

 	err = bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL);
 	ASSERT_OK(err, "XDP program detach");
@@ -203,8 +206,11 @@ static void test_xdp_with_cpumap_helpers_veth(void)
 	err = bpf_prog_test_run_opts(cm_fd_redir, &opts);
 	ASSERT_OK(err, "XDP test run");

-	/* wait for the packets to be flushed */
+	/* wait for the packets to be flushed, then check that redirect has been
+	 * performed
+	 */
 	kern_sync_rcu();
+	ASSERT_NEQ(skel->bss->redirect_count, 0, "redirected packets");

 	err = bpf_xdp_detach(ifindex_src, XDP_FLAGS_DRV_MODE, NULL);
 	ASSERT_OK(err, "XDP program detach");
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_with_cpumap_helpers.c b/tools/testing/selftests/bpf/progs/test_xdp_with_cpumap_helpers.c
index d848fe96924e32a72e1e0327e3afffeb349b933e..3619239b01b741dfd81bbebf5d9a62e0cf71e4f4 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_with_cpumap_helpers.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_with_cpumap_helpers.c
@@ -12,6 +12,8 @@ struct {
 	__uint(max_entries, 4);
 } cpu_map SEC(".maps");

+__u32 redirect_count = 0;
+
 SEC("xdp")
 int xdp_redir_prog(struct xdp_md *ctx)
 {
@@ -27,6 +29,9 @@ int xdp_dummy_prog(struct xdp_md *ctx)
 SEC("xdp/cpumap")
 int xdp_dummy_cm(struct xdp_md *ctx)
 {
+	if (bpf_get_smp_processor_id() == 0)
+		redirect_count++;
+
 	if (ctx->ingress_ifindex == IFINDEX_LO)
 		return XDP_DROP;

-- 
2.46.2