net80211 inactivity processing

[Andriy Voskoboinyk]

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

> 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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