rtnetlink: propagate error from dev_change_flags in do_setlink()

rtnetlink: propagate error from dev_change_flags in do_setlink()

[Johannes Berg]

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])

Re: rtnetlink: propagate error from dev_change_flags in do_setlink()

[Johannes Berg]

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On Sun, 2008-11-16 at 14:10 +0100, Johannes Berg wrote:
> 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>

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

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Re: rtnetlink: propagate error from dev_change_flags in do_setlink()

[David Miller]

From: Johannes Berg <johannes@sipsolutions.net>
Date: Sun, 16 Nov 2008 14:16:08 +0100

> On Sun, 2008-11-16 at 14:10 +0100, Johannes Berg wrote:
> > 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>

Patch applied.

> 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.

I'll queue it up for -stable, thanks.