selftests/bpf: Fix return value checks in perf_event_stackmap test

The bpf_get_stackid() function may also return 0 on success as per UAPI BPF
helper documentation. Therefore, correct checks from 'val > 0' to 'val >= 0'
to ensure that they cover all possible success return values.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220408041452.933944-1-ytcoode@gmail.com

diff --git a/tools/testing/selftests/bpf/progs/perf_event_stackmap.c b/tools/testing/selftests/bpf/progs/perf_event_stackmap.c
index b3fcb52..f793280 100644 (file)
--- a/tools/testing/selftests/bpf/progs/perf_event_stackmap.c
+++ b/tools/testing/selftests/bpf/progs/perf_event_stackmap.c
@@ -35,10 +35,10 @@ int oncpu(void *ctx)
        long val;
 
        val = bpf_get_stackid(ctx, &stackmap, 0);
-       if (val > 0)
+       if (val >= 0)
                stackid_kernel = 2;
        val = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK);
-       if (val > 0)
+       if (val >= 0)
                stackid_user = 2;
 
        trace = bpf_map_lookup_elem(&stackdata_map, &key);