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>

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 8368b7e..a8c3a33 100644 (file)
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -528,6 +528,8 @@ static int do_show(int argc, char **argv)
 
                fd = bpf_map_get_fd_by_id(id);
                if (fd < 0) {
+                       if (errno == ENOENT)
+                               continue;
                        p_err("can't get map by id (%u): %s",
                              id, strerror(errno));
                        break;

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index ad619b9..dded773 100644 (file)
--- 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;