Patchwork [-next] openvswitch: fix error return code in ovs_vport_cmd_set()

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Submitter Wei Yongjun
Date March 20, 2013, 12:14 p.m.
Message ID <CAPgLHd_6+xnMKZBzH3KySpFv7hUzzNot7GBYSCAPLDRbC5HjsA@mail.gmail.com>
Download mbox | patch
Permalink /patch/229369/
State Changes Requested
Delegated to: David Miller
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Comments

Wei Yongjun - March 20, 2013, 12:14 p.m.
From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>

Fix to return a negative error code from the error handling
case instead of 0, as returned elsewhere in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
---
 net/openvswitch/datapath.c | 1 +
 1 file changed, 1 insertion(+)


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Jesse Gross - March 20, 2013, 3:57 p.m.
On Wed, Mar 20, 2013 at 5:14 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>
> Fix to return a negative error code from the error handling
> case instead of 0, as returned elsewhere in this function.
>
> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>

This isn't right because at this point in the function the change has
already been made, only the notification allocation failed.  Therefore
we don't want to return an error since the caller will assume that
nothing has changed; instead an error is set on the Netlink socket.
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David Miller - March 20, 2013, 4:22 p.m.
From: Jesse Gross <jesse@nicira.com>
Date: Wed, 20 Mar 2013 08:57:53 -0700

> On Wed, Mar 20, 2013 at 5:14 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
>> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>
>> Fix to return a negative error code from the error handling
>> case instead of 0, as returned elsewhere in this function.
>>
>> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
> 
> This isn't right because at this point in the function the change has
> already been made, only the notification allocation failed.  Therefore
> we don't want to return an error since the caller will assume that
> nothing has changed; instead an error is set on the Netlink socket.

Then the way to fix this is to allocate the netlink SKB first, before
any config changes occur, then pass that SKB into ovs_vport_cmd_build_info.

We can still get errors, for -EMSGSIZE situations, but I'd say that'd
be an implementation bug that should be logged.  If we aren't allocating
large enough SKBs for the netlink reply, that's really an internal
error.
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Jesse Gross - March 21, 2013, 12:06 a.m.
On Wed, Mar 20, 2013 at 9:22 AM, David Miller <davem@davemloft.net> wrote:
> From: Jesse Gross <jesse@nicira.com>
> Date: Wed, 20 Mar 2013 08:57:53 -0700
>
>> On Wed, Mar 20, 2013 at 5:14 AM, Wei Yongjun <weiyj.lk@gmail.com> wrote:
>>> From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>>
>>> Fix to return a negative error code from the error handling
>>> case instead of 0, as returned elsewhere in this function.
>>>
>>> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
>>
>> This isn't right because at this point in the function the change has
>> already been made, only the notification allocation failed.  Therefore
>> we don't want to return an error since the caller will assume that
>> nothing has changed; instead an error is set on the Netlink socket.
>
> Then the way to fix this is to allocate the netlink SKB first, before
> any config changes occur, then pass that SKB into ovs_vport_cmd_build_info.
>
> We can still get errors, for -EMSGSIZE situations, but I'd say that'd
> be an implementation bug that should be logged.  If we aren't allocating
> large enough SKBs for the netlink reply, that's really an internal
> error.

That solves the problem here.  I'll take care of it, thanks.
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Patch

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index d61cd99..1ee11c3 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1736,6 +1736,7 @@  static int ovs_vport_cmd_set(struct sk_buff *skb, struct genl_info *info)
 
 	reply = ovs_vport_cmd_build_info(vport, info->snd_portid, info->snd_seq,
 					 OVS_VPORT_CMD_NEW);
+	err = PTR_ERR(reply);
 	if (IS_ERR(reply)) {
 		netlink_set_err(sock_net(skb->sk)->genl_sock, 0,
 				ovs_dp_vport_multicast_group.id, PTR_ERR(reply));