net80211 inactivity processing
Adrian Chadd
adrian.chadd at gmail.com
Tue Feb 23 06:26:38 UTC 2016
On 22 February 2016 at 09:39, Andriy Voskoboinyk <avos at freebsd.org> wrote:
> Mon, 22 Feb 2016 03:43:51 +0200 було написано Adrian Chadd
> <adrian.chadd at gmail.com>:
>
> Because control frames are disabled by default? (the timer is refreshed
> every time when a frame goes into input path (ni->ni_inact =
> ni->ni_inact_reload)).
> This may be added to TX callback (already implemented in
> https://reviews.freebsd.org/D5147); however, I have no idea what to do with
Right.
I need to go digging a little more about it. It's a good catch; I just
need to see whether to kill the code or whether to go back to the
older way of handling node expiry.
-a
>
>
>> drivers that lie about frame completion/failure
>
>
>> Hi,
>>
>> I think it is a hold-over from how node reclaimation used to work.
>> Sending null data frames to probe if a station is still there is a
>> common thing to do. So yeah, maybe we should go figure out why the
>> inactivity timer isn't kicked if the NULL data frame succeeds (ie, the
>> driver explicitly gives us ACK feedback, rather than drivers that lie
>> about frame completion/failure.)
>>
>>
>>
>> -adrian
>>
>>
>> On 21 February 2016 at 16:34, Andriy Voskoboinyk <avos at freebsd.org> wrote:
>>>
>>> Hi,
>>>
>>> What is the purpose of the following code? (especially in HOSTAP mode)
>>> (ieee80211_node.c):
>>>
>>> static void
>>> ieee80211_timeout_stations(struct ieee80211com *ic)
>>> {
>>> struct ieee80211_node_table *nt = &ic->ic_sta;
>>> struct ieee80211vap *vap;
>>> struct ieee80211_node *ni;
>>> int gen = 0;
>>>
>>> IEEE80211_NODE_ITERATE_LOCK(nt);
>>> gen = ++nt->nt_scangen;
>>> restart:
>>> IEEE80211_NODE_LOCK(nt);
>>> TAILQ_FOREACH(ni, &nt->nt_node, ni_list) {
>>> ...
>>> if ((vap->iv_flags_ext & IEEE80211_FEXT_INACT) &&
>>> (0 < ni->ni_inact &&
>>> ni->ni_inact <= vap->iv_inact_probe) &&
>>> ni->ni_rates.rs_nrates != 0) {
>>> IEEE80211_NOTE(vap,
>>> IEEE80211_MSG_INACT |
>>> IEEE80211_MSG_NODE,
>>> ni, "%s",
>>> "probe station due to inactivity");
>>> /*
>>> * Grab a reference before unlocking the
>>> table
>>> * so the node cannot be reclaimed before
>>> we
>>> * send the frame.
>>> ieee80211_send_nulldata
>>> * understands we've done this and
>>> reclaims
>>> the
>>> * ref for us as needed.
>>> */
>>> ieee80211_ref_node(ni);
>>> IEEE80211_NODE_UNLOCK(nt);
>>> ieee80211_send_nulldata(ni);
>>> <<<
>>> here
>>> /* XXX stat? */
>>> goto restart;
>>> }
>>> ...
>>> }
>>> IEEE80211_NODE_UNLOCK(nt);
>>>
>>> IEEE80211_NODE_ITERATE_UNLOCK(nt);
>>> }
>>>
>>> As for me, ieee80211_send_nulldata() will not refresh ni->ni_inact,
>>> nor will trigger any data transmission from the STA (so, it does
>>> nothing?).
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