From: Tamizh chelvam <tamizhr@codeaurora.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org
Subject: Re: [PATCH 3/3] mac80211: Implement functionality to monitor station's signal stregnth
Date: Sun, 11 Nov 2018 19:33:33 +0530 [thread overview]
Message-ID: <46190175cf4e7cf054ee15aef5ea1890@codeaurora.org> (raw)
In-Reply-To: <f9be46875c90f00a79f03838944bbf23f05d2c0d.camel@sipsolutions.net>
On 2018-11-09 17:25, Johannes Berg wrote:
> Oh, umm, that patch is still here ...
>
> I guess we can combine 2 and 3 too.
>
>
Sure.
>> + if (sta->rssi_low && bss_conf->enable_beacon) {
>> + int last_event =
>> + sta->last_rssi_event_value;
>> + int sig = -ewma_signal_read(&sta->rx_stats_avg.signal);
>> + int low = sta->rssi_low;
>> + int high = sta->rssi_high;
>
> This doesn't really support a list, like in patch 2 where you store
> sta_info::rssi_tholds?
>
rssi_low and rssi_high will have a configured value or zero know ?
Configured value has been stored in the previous patch.
>> + if (sig < low &&
>> + (last_event == 0 || last_event >= low)) {
>> + sta->last_rssi_event_value = sig;
>> + cfg80211_sta_mon_rssi_notify(
>> + rx->sdata->dev, sta->addr,
>> + NL80211_CQM_RSSI_THRESHOLD_EVENT_LOW,
>> + sig, GFP_ATOMIC);
>> + rssi_cross = true;
>> + } else if (sig > high &&
>> + (last_event == 0 || last_event <= high)) {
>> + sta->last_rssi_event_value = sig;
>> + cfg80211_sta_mon_rssi_notify(
>> + rx->sdata->dev, sta->addr,
>> + NL80211_CQM_RSSI_THRESHOLD_EVENT_HIGH,
>> + sig, GFP_ATOMIC);
>> + rssi_cross = true;
>> + }
>> + }
>> +
>> + if (rssi_cross) {
>> + ieee80211_update_rssi_config(sta);
>> + rssi_cross = false;
>> + }
>> +}
>
> Ah, but it does, just hard to understand.
>
> However, this does mean what I suspected on the other patch is true -
> you're calling ieee80211_update_rssi_config() here, and that uses the
> sta->rssi_tholds array without any protection, while a concurrent
> change
> of configuration can free the data.
>
yes, I'll add a protection mechanism.
> You need to sort that out. I would suggest to stick all the sta->rssi_*
> fields you add into a new struct (you even had an empty one), and
> protect that struct using RCU. That also saves the memory in case it's
> not assigned at all. Something like
>
> struct sta_mon_rssi_config {
> struct rcu_head rcu_head;
> int n_thresholds;
> s32 low, high;
> u32 hyst;
> s32 last_value;
> s32 thresholds[];
> };
>
> then you can kfree_rcu() it, and just do a single allocation using
> struct_size() for however many entries you need.
>
Yes correct. I'll change it.
>> + * @count_rx_signal: Number of data frames used in averaging station
>> signal.
>> + * This can be used to avoid generating less reliable station rssi
>> cross
>> + * events that would be based only on couple of received frames.
>> */
>> struct sta_info {
>> /* General information, mostly static */
>> @@ -600,6 +603,7 @@ struct sta_info {
>> s32 rssi_high;
>> u32 rssi_hyst;
>> s32 last_rssi_event_value;
>> + unsigned int count_rx_signal;
>
> I guess that would also move into the new struct.
>
Okay.
Thanks,
Tamizh.
prev parent reply other threads:[~2018-11-11 14:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 17:57 [PATCH 0/3] cfg80211/mac80211: Add support to configure and monitor station's rssi threshold Tamizh chelvam
2018-10-15 17:57 ` [PATCH 1/3] cfg80211: Add support to configure station specific RSSI threshold for AP mode Tamizh chelvam
2018-10-16 11:28 ` Sergey Matyukevich
2018-10-16 12:47 ` [EXTERNAL] " Tamizh Chelvam Raja
2018-11-09 11:44 ` Johannes Berg
2018-11-11 13:34 ` Tamizh chelvam
2018-10-15 17:57 ` [PATCH 2/3] mac80211: Implement API to configure station specific rssi threshold Tamizh chelvam
2018-11-09 11:49 ` Johannes Berg
2018-11-11 13:57 ` Tamizh chelvam
2018-10-15 17:57 ` [PATCH 3/3] mac80211: Implement functionality to monitor station's signal stregnth Tamizh chelvam
2018-10-16 11:49 ` Sergey Matyukevich
2018-11-09 11:55 ` Johannes Berg
2018-11-11 14:03 ` Tamizh chelvam [this message]
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