Re: [PATCH v3 bpf-next 9/9] selftest: add tests for XDP programs in CPUMAP entries

On Tue, Jun 23, 2020 at 2:40 PM Lorenzo Bianconi [off-list ref] wrote:

quoted

Similar to what have been done for DEVMAP, introduce tests to verify

[...]

quoted

+SEC("xdp_cpumap/dummy_cm")
+int xdp_dummy_cm(struct xdp_md *ctx)
+{
+       char fmt[] = "devmap redirect: dev %u len %u\n";
+       void *data_end = (void *)(long)ctx->data_end;
+       void *data = (void *)(long)ctx->data;
+       unsigned int len = data_end - data;
+
+       ingress_ifindex = ctx->ingress_ifindex;

Have you checked the generated BPF assembly to verify
ctx->ingress_ifindex is actually read? ingress_ifindex variable is
declared static, so I'm guessing Clang just optimized it away. If you
want to be sure this actually gets executed, make ingress_ifindex
global var.

ack, thx for the review. I will fix it in v4.

Regards,
Lorenzo

quoted

+
+       return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.26.2