From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH 4/6] net: add NL802154 interface for configuration of 802.15.4 devices Date: Thu, 04 Jun 2009 17:12:08 +0200 Message-ID: <4A27E448.3040305@trash.net> References: <1244021629-18409-4-git-send-email-dbaryshkov@gmail.com> <1244021629-18409-5-git-send-email-dbaryshkov@gmail.com> <1244021964.10665.5.camel@johannes.local> <20090603.030911.162861804.davem@davemloft.net> <20090603105256.GB20508@doriath.ww600.siemens.net> <1244027110.1693.9.camel@johannes.local> <20090603122744.GC20508@doriath.ww600.siemens.net> <1244124749.22576.71.camel@johannes.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Johannes Berg , David Miller , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, sfr-3FnU+UHB4dNDw9hX6IcOSA@public.gmane.org, slapin-9cOl001CZnBAfugRpC6u6w@public.gmane.org To: Dmitry Eremin-Solenikov Return-path: In-Reply-To: Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org Dmitry Eremin-Solenikov wrote: > 2009/6/4 Johannes Berg : >> On Wed, 2009-06-03 at 16:27 +0400, Dmitry Eremin-Solenikov wrote: >> >>>>> +static int ieee802154_nl_put_failure(struct sk_buff *msg) >>>>> +{ >>>>> + void *hdr = genlmsg_data(NLMSG_DATA(msg->data)); /* XXX: nlh is right at the start of msg */ >>>>> + genlmsg_cancel(msg, hdr); >>>>> + nlmsg_free(msg); >>>>> + return -ENOBUFS; >>>>> +} >>>> This seems weird. >>> Why? >> Because it's strange to cancel then free? > >>>From looking at the other code, the usual pattern for netlink is > (please, correct me if I'm wrong): > > int fill (....) > { > genlmsg_put(); > NLA_PUT(...) > NLA_PUT(...) > return genlmsg_end(); > > nla_put_failure: > genlmsg_cancel(); > return -EMSGSIZE; > } > > int cmd(...) > { > int rc; > nlmsg_new(); > > rc = fill(); > if (rc < 0) > goto out; > > genlmsg_unicast(); > > out: > nlmsg_free(); > return -ENOBUFS; > } > > This is equivalent to our code: > > sk_buff *new() > { > msg = nlmsg_new(); > genlmsg_put(); > return msg; > } canceling messages is only necessary in fill functions that are also used for dumps, where as many elements are stuffed in the skb as possible. When the last element doesn't completely fit, its removed again (canceled) and put into the next skb. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html