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>

---

 net/core/rtnetlink.c |    4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)
--- everything.orig/net/core/rtnetlink.c	2008-10-26 20:00:12.000000000 +0100

+++ everything/net/core/rtnetlink.c	2008-11-11 23:24:14.000000000 +0100

@@ -878,7 +878,9 @@ static int do_setlink(struct net_device

 		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])
--

Maybe add

Cc: stable@kernel.org [since the beginning of time^Wgit]
when committing? Not sure it's appropriate for stable since so far

nobody complained, I suspect people just use the ioctl anyway.
johannes

From: Johannes Berg <johannes@sipsolutions.net>
I'll queue it up for -stable, thanks.

--