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

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Date:   Wed,  3 Jun 2020 21:03:47 +0200
From:   Matthieu Baerts <matthieu.baerts@...sares.net>
To:     alexei.starovoitov@...il.com
Cc:     andriin@...com, ast@...nel.org, bpf@...r.kernel.org,
        daniel@...earbox.net, davem@...emloft.net, fejes@....elte.hu,
        john.fastabend@...il.com, kafai@...com, kpsingh@...omium.org,
        kuba@...nel.org, linux-kernel@...r.kernel.org,
        matthieu.baerts@...sares.net, netdev@...r.kernel.org,
        songliubraving@...com, yhs@...com
Subject: [PATCH bpf v2] bpf: fix unused-var without NETDEVICES

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@...il.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@...sares.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