[PATCH bpf v2] bpf: fix unused-var without NETDEVICES

From: Matthieu Baerts <matthieu.baerts@tessares.net>
To: alexei.starovoitov@gmail.com
Cc: andriin@fb.com, ast@kernel.org, bpf@vger.kernel.org,
	daniel@iogearbox.net, davem@davemloft.net, fejes@inf.elte.hu,
	john.fastabend@gmail.com, kafai@fb.com, kpsingh@chromium.org,
	kuba@kernel.org, linux-kernel@vger.kernel.org,
	matthieu.baerts@tessares.net, netdev@vger.kernel.org,
	songliubraving@fb.com, yhs@fb.com
Subject: [PATCH bpf v2] bpf: fix unused-var without NETDEVICES
Date: Wed,  3 Jun 2020 21:03:47 +0200	[thread overview]
Message-ID: <20200603190347.2310320-1-matthieu.baerts@tessares.net> (raw)
In-Reply-To: <CAADnVQ+k7+fQmuNQL=GLLaGUvd5+zZN6GViy-oP7Sfq7aQVG1Q@mail.gmail.com>

A recent commit added new variables only used if CONFIG_NETDEVICES is
set. A simple fix would be to only declare these variables if the same
condition is valid but Alexei suggested an even simpler solution:

    since CONFIG_NETDEVICES doesn't change anything in .h I think the
    best is to remove #ifdef CONFIG_NETDEVICES from net/core/filter.c
    and rely on sock_bindtoindex() returning ENOPROTOOPT in the extreme
    case of oddly configured kernels.

Fixes: 70c58997c1e8 ("bpf: Allow SO_BINDTODEVICE opt in bpf_setsockopt")
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---

Notes:
    This fix currently applies on net-next and bpf-next only. Except that
    net-next is now closed and -net will get commits from net-next after
    Linus' pull.

    v2: remove #ifdef CONFIG_NETDEVICES (Alexei)

 net/core/filter.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index d01a244b5087..90d2eb77002f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4340,8 +4340,6 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 			}
 			break;
 		case SO_BINDTODEVICE:
-			ret = -ENOPROTOOPT;
-#ifdef CONFIG_NETDEVICES
 			optlen = min_t(long, optlen, IFNAMSIZ - 1);
 			strncpy(devname, optval, optlen);
 			devname[optlen] = 0;
@@ -4360,7 +4358,6 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
 				dev_put(dev);
 			}
 			ret = sock_bindtoindex(sk, ifindex, false);
-#endif
 			break;
 		default:
 			ret = -EINVAL;
-- 
2.25.1

