netdev - [PATCH bpf 2/2] tools: bpftool: protect against races with disappearing objects

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Message-Id: <20171222193606.19786-3-jakub.kicinski@netronome.com>
Date:   Fri, 22 Dec 2017 11:36:06 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     netdev@...r.kernel.org, daniel@...earbox.net,
        alexei.starovoitov@...il.com
Cc:     oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH bpf 2/2] 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@...ronome.com>
Acked-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
 tools/bpf/bpftool/map.c  | 2 ++
 tools/bpf/bpftool/prog.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 8368b7ea31b5..a8c3a33dd185 100644
--- 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 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;
-- 
2.15.1