From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Fri, 22 Dec 2017 11:36:06 -0800
Subject: tools: bpftool: protect against races with disappearing objects
Patch-mainline: v4.15-rc6
Git-commit: 8207c6dd4746c345b689684c4cd0ce00a18c7ef2
References: bsc#1109837

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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 tools/bpf/bpftool/map.c  |    2 ++
 tools/bpf/bpftool/prog.c |    2 ++
 2 files changed, 4 insertions(+)

--- 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;
--- 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;