From: Pavel Emelyanov <xemul@parallels•com>
To: Cyrill Gorcunov <gorcunov@openvz•org>
Cc: NETDEV <netdev@vger•kernel.org>,
David Miller <davem@davemloft•net>,
Eric Dumazet <eric.dumazet@gmail•com>
Subject: Re: [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed
Date: Sat, 03 Nov 2012 20:17:50 +0400 [thread overview]
Message-ID: <509543AE.1020902@parallels.com> (raw)
In-Reply-To: <20121102173550.GH10877@moon>
On 11/02/2012 09:35 PM, Cyrill Gorcunov wrote:
> We've observed that in case if UDP diag module is not
> supported in kernel the netlink returns NLMSG_DONE without
> notifying a caller that handler is missed.
>
> This patch makes netlink_dump to return error code instead.
>
> So as example it become possible to detect such situation
> and handle it gracefully on userspace level.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz•org>
> CC: David Miller <davem@davemloft•net>
> CC: Eric Dumazet <eric.dumazet@gmail•com>
> CC: Pavel Emelyanov <xemul@parallels•com>
> ---
> net/ipv4/inet_diag.c | 5 ++++-
> net/netlink/af_netlink.c | 4 ++++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.git/net/ipv4/inet_diag.c
> ===================================================================
> --- linux-2.6.git.orig/net/ipv4/inet_diag.c
> +++ linux-2.6.git/net/ipv4/inet_diag.c
> @@ -895,13 +895,16 @@ static int __inet_diag_dump(struct sk_bu
> struct inet_diag_req_v2 *r, struct nlattr *bc)
> {
> const struct inet_diag_handler *handler;
> + int err = 0;
>
> handler = inet_diag_lock_handler(r->sdiag_protocol);
> if (!IS_ERR(handler))
> handler->dump(skb, cb, r, bc);
> + else
> + err = PTR_ERR(handler);
> inet_diag_unlock_handler(handler);
>
> - return skb->len;
> + return err ? : skb->len;
> }
>
> static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
> Index: linux-2.6.git/net/netlink/af_netlink.c
> ===================================================================
> --- linux-2.6.git.orig/net/netlink/af_netlink.c
> +++ linux-2.6.git/net/netlink/af_netlink.c
> @@ -1740,6 +1740,10 @@ static int netlink_dump(struct sock *sk)
> else
> __netlink_sendskb(sk, skb);
> return 0;
> + } else if (len < 0) {
> + err = len;
> + nlk->cb = NULL;
> + goto errout_skb;
When family-level handler is absent and sock_diag returns error this error
gets propagated back to user without this fix. Why do we need it in case
we return error from protocol-level handler?
> }
>
> nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
> .
>
next prev parent reply other threads:[~2012-11-03 16:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-02 17:35 [RFC] net: netlink -- Allow netlink_dump to return error code if protocol handler is missed Cyrill Gorcunov
2012-11-03 16:17 ` Pavel Emelyanov [this message]
2012-11-03 16:39 ` Cyrill Gorcunov
2012-11-03 19:16 ` Cyrill Gorcunov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=509543AE.1020902@parallels.com \
--to=xemul@parallels$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=eric.dumazet@gmail$(echo .)com \
--cc=gorcunov@openvz$(echo .)org \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox