Re: [PATCH] mac80211: Ensure vif queues are operational after start

[Ben Greear <greearb@candelatech.com>]

On 9/15/22 1:06 PM, Alexander Wetzel wrote:
>>
>> I've got some doubts that my fix is correct...
>> While it fixes the problem in my tests it looks like we'll need another queue restart to get the queues working again.
>>
>> After all IEEE80211_TXQ_STOP_NETIF_TX will not be cleared when it has been set by __ieee80211_stop_queue().
>>
>> I'll update the patch and skip setting vif.txqs_stopped when SDATA_STATE_RUNNING is not set. Not having IEEE80211_TXQ_STOP_NETIF_TX set looks harmless, having 
>> it set when it should less problematic...
> 
> Scratch that: The patch should be ok as it is: IEEE80211_TXQ_STOP_NETIF_TX is not set on stop, the patch should be ok as it is.
> 
> Sorry for the noise.
> 
> Alexander
> 

To add to the noise...

 From reading the original patch description, it was to stop an NPE when AP was stopped.  I have been testing
this patch below and it fixes the problems I saw with multiple vdevs.  I was worried that
the code in the 'list_for_each_entry_rcu(sta, &local->sta_list, list) {' might still need to run
to keep everything in sync (and my patch allows that to happen), but I do not know if that is true or not.

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index c768e583aad4..2b5dafe9f4cc 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -370,12 +370,6 @@ static void __ieee80211_wake_txqs(struct ieee80211_sub_if_data *sdata, int ac)
         local_bh_disable();
         spin_lock(&fq->lock);

-       if (!test_bit(SDATA_STATE_RUNNING, &sdata->state))
-               goto out;
-
-       if (sdata->vif.type == NL80211_IFTYPE_AP)
-               ps = &sdata->bss->ps;
-
         sdata->vif.txqs_stopped[ac] = false;

         list_for_each_entry_rcu(sta, &local->sta_list, list) {
@@ -408,6 +402,10 @@ static void __ieee80211_wake_txqs(struct ieee80211_sub_if_data *sdata, int ac)

         txqi = to_txq_info(vif->txq);

+       if (test_bit(SDATA_STATE_RUNNING, &sdata->state))
+               if (sdata->vif.type == NL80211_IFTYPE_AP)
+                       ps = &sdata->bss->ps;
+
         if (!test_and_clear_bit(IEEE80211_TXQ_STOP_NETIF_TX, &txqi->flags) ||
             (ps && atomic_read(&ps->num_sta_ps)) || ac != vif->txq->ac)
                 goto out;


Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com