[PATCH bpf-next 1/2] bpftool: adjust for error codes from libbpf probes

From: Milan Landaverde
Date: Wed May 04 2022 - 12:15:04 EST


Originally [1], libbpf's (now deprecated) probe functions returned a bool
to acknowledge support but the new APIs return an int with a possible
negative error code to reflect probe failure. This change decides for
bpftool to declare maps and helpers are not available on probe failures.

[1]: https://lore.kernel.org/bpf/20220202225916.3313522-3-andrii@xxxxxxxxxx/

Signed-off-by: Milan Landaverde <milan@xxxxxxxxxxxx>
---
tools/bpf/bpftool/feature.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index be130e35462f..c532c8855c24 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -638,7 +638,7 @@ probe_map_type(enum bpf_map_type map_type, const char *define_prefix,

res = probe_map_type_ifindex(map_type, ifindex);
} else {
- res = libbpf_probe_bpf_map_type(map_type, NULL);
+ res = libbpf_probe_bpf_map_type(map_type, NULL) > 0;
}

/* Probe result depends on the success of map creation, no additional
@@ -701,7 +701,7 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
if (ifindex)
res = probe_helper_ifindex(id, prog_type, ifindex);
else
- res = libbpf_probe_bpf_helper(prog_type, id, NULL);
+ res = libbpf_probe_bpf_helper(prog_type, id, NULL) > 0;
#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for
* unprivileged users check that we did not fail because of
--
2.32.0