strerror() expects a positive errno, however variable err will never be positive when an error occurs. This causes bpftool to output too many "unknown error", even a simple "file not exist" error can not get an accurate message. This patch fixed all "strerror(err)" patterns in bpftool. Specially in btf.c#L823, hashmap__append() is an internal function of libbpf and will not change errno, so there's a little difference. Some libbpf_get_error() calls are kept for return values. Changes since v1: https://lore.kernel.org/bpf/SY4P282MB1084B61CD8671DFA395AA8579D539@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Check directly for NULL values instead of calling libbpf_get_error(). Signed-off-by: Tianyi Liu <i.pear@xxxxxxxxxxx> --- tools/bpf/bpftool/btf.c | 11 +++++------ tools/bpf/bpftool/gen.c | 4 ++-- tools/bpf/bpftool/map_perf_ring.c | 7 +++---- 3 files changed, 10 insertions(+), 12 deletions(-) diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 0744bd115..933177bdd 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -640,10 +640,9 @@ static int do_dump(int argc, char **argv) btf = btf__parse_split(*argv, base ?: base_btf); err = libbpf_get_error(btf); - if (err) { - btf = NULL; + if (!btf) { p_err("failed to load BTF from %s: %s", - *argv, strerror(err)); + *argv, strerror(errno)); goto done; } NEXT_ARG(); @@ -688,8 +687,8 @@ static int do_dump(int argc, char **argv) btf = btf__load_from_kernel_by_id_split(btf_id, base_btf); err = libbpf_get_error(btf); - if (err) { - p_err("get btf by id (%u): %s", btf_id, strerror(err)); + if (!btf) { + p_err("get btf by id (%u): %s", btf_id, strerror(errno)); goto done; } } @@ -825,7 +824,7 @@ build_btf_type_table(struct hashmap *tab, enum bpf_obj_type type, u32_as_hash_field(id)); if (err) { p_err("failed to append entry to hashmap for BTF ID %u, object ID %u: %s", - btf_id, id, strerror(errno)); + btf_id, id, strerror(-err)); goto err_free; } } diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 7070dcffa..cf8b4e525 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -1594,14 +1594,14 @@ static int do_object(int argc, char **argv) err = bpf_linker__add_file(linker, file, NULL); if (err) { - p_err("failed to link '%s': %s (%d)", file, strerror(err), err); + p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno); goto out; } } err = bpf_linker__finalize(linker); if (err) { - p_err("failed to finalize ELF file: %s (%d)", strerror(err), err); + p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno); goto out; } diff --git a/tools/bpf/bpftool/map_perf_ring.c b/tools/bpf/bpftool/map_perf_ring.c index 6b0c41015..309d5a1e6 100644 --- a/tools/bpf/bpftool/map_perf_ring.c +++ b/tools/bpf/bpftool/map_perf_ring.c @@ -195,10 +195,9 @@ int do_event_pipe(int argc, char **argv) opts.map_keys = &ctx.idx; pb = perf_buffer__new_raw(map_fd, MMAP_PAGE_CNT, &perf_attr, print_bpf_output, &ctx, &opts); - err = libbpf_get_error(pb); - if (err) { + if (!pb) { p_err("failed to create perf buffer: %s (%d)", - strerror(err), err); + strerror(errno), errno); goto err_close_map; } @@ -213,7 +212,7 @@ int do_event_pipe(int argc, char **argv) err = perf_buffer__poll(pb, 200); if (err < 0 && err != -EINTR) { p_err("perf buffer polling failed: %s (%d)", - strerror(err), err); + strerror(errno), errno); goto err_close_pb; } } -- 2.37.3
