rtnetlink: propagate error from dev_change_flags in do_setlink()

Unlike ifconfig, iproute doesn't report an error when setting
an interface up fails:

(example: put wireless network mac80211 interface into repeater mode
with iwconfig but do not set a peer MAC address, it should fail with
-ENOLINK)

without patch:
# ip link set wlan0 up ; echo $?
0
# 

with patch:
# ip link set wlan0 up ; echo $?
RTNETLINK answers: Link has been severed
2
# 

Propagate the return value from dev_change_flags() to fix this.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 31f29d2989fd..4dfb6b4d4559 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -878,7 +878,9 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
                 if (ifm->ifi_change)
                         flags = (flags & ifm->ifi_change) |
                                 (dev->flags & ~ifm->ifi_change);
-                dev_change_flags(dev, flags);
+                err = dev_change_flags(dev, flags);
+                if (err < 0)
+                        goto errout;
         }
 
         if (tb[IFLA_TXQLEN])