2009/6/4 Patrick McHardy <kaber@xxxxxxxxx>:
> Dmitry Eremin-Solenikov wrote:
>>
>> 2009/6/4 Johannes Berg <johannes@xxxxxxxxxxxxxxxx>:
>>>
>>> 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.
Understood. So you'd suggest just to drop the genlmsg_cancel()
from the failure call chain?
--
With best wishes
Dmitry
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