tools: bpftool: protect against races with disappearing objects

On program/map show we may get an ID of an object from GETNEXT,
but the object may disappear before we call GET_FD_BY_ID.  If
that happens, ignore the object and continue.

Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index ad619b96c276..dded77345bfb 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -382,6 +382,8 @@ static int do_show(int argc, char **argv)
 
                 fd = bpf_prog_get_fd_by_id(id);
                 if (fd < 0) {
+                        if (errno == ENOENT)
+                                continue;
                         p_err("can't get prog by id (%u): %s",
                               id, strerror(errno));
                         err = -1;