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@bootlin.com>
Link: https://lore.kernel.org/r/20241009-convert_xdp_tests-v3-3-51cea913710c@bootlin.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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 88e8a886d1e611d2fc5e8891e8304ad8aa7e5a38..c7f74f068e78835329f0b1e35c2dffb54adfe3ae 100644 (file)
--- 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");

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 (file)
--- 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;