Subject: Re: [RFC PATCH v3 04/12] mac80211: Compatibility Extended Key ID
 support
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org
References: <20190210210620.31181-1-alexander@wetzel-home.de>
 <20190210210620.31181-5-alexander@wetzel-home.de>
 <0519f25cf73d8a91202e40b08e94de8d2520411e.camel@sipsolutions.net>
From:   Alexander Wetzel <alexander@wetzel-home.de>
Message-ID: <bad49ffb-5334-03f5-62e0-4f06d7c36242@wetzel-home.de>
Date:   Thu, 21 Feb 2019 21:07:13 +0100
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> 
>> +	if (!ext_native && key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
>> +		key->flags |= KEY_FLAG_RX_SW_CRYPTO;
>> +		/* Activate Rx crypto offload after max 10s when idle */
>> +		ieee80211_queue_delayed_work(&local->hw, &sta->ext_key_compat_wk,
>> +					     round_jiffies_relative(HZ * 10));
>> +	}
> 
> Is there much point in this?
> 
>> +		if (unlikely(rx->key->flags & KEY_FLAG_RX_SW_CRYPTO)) {
>> +			rx->key->flags &= ~KEY_FLAG_RX_SW_CRYPTO;
>> +			cancel_delayed_work(&rx->sta->ext_key_compat_wk);
>> +			ieee80211_queue_delayed_work(&rx->local->hw,
>> +						     &rx->sta->ext_key_compat_wk, 0);
>> +		}
> 
> We'll almost certainly do it from here, so never exercise the other
> path?

This is mostly to have a definite time we know the new key is used also 
for RX. In probably 99.9% of all cases it will be triggered from the Rx 
path.
Some special purpose devices may not send any packets for a long time 
and trigger the fallback, as (wrong) firewall rules. (I've e.g. tested 
it by dropping all outgoing packets on the remote sta.)

The idea was to be sure that a rekey intervall >10s prevents activating 
Rx crypt when rekeying the next key. Which now sounds kind of thin...

So I'll remove the 10s fallback.