From: Felix Fietkau <nbd@nbd.name>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
linux-wireless <linux-wireless@vger.kernel.org>,
Ryder Lee <ryder.lee@mediatek.com>, Roy Luo <royluo@google.com>
Subject: Re: [PATCH 5.3] mt76: mt76x0e: don't use hw encryption for MT7630E
Date: Wed, 21 Aug 2019 11:03:00 +0200 [thread overview]
Message-ID: <433c1d1f-3590-375f-ed8d-c9de2af873d5@nbd.name> (raw)
In-Reply-To: <20190821084724.GB20223@redhat.com>
On 2019-08-21 10:47, Stanislaw Gruszka wrote:
> On Tue, Aug 20, 2019 at 01:24:39PM +0200, Stanislaw Gruszka wrote:
>> > Can you test if disabling hw encryption only for shared or only for
>> > pairwise keys makes any difference?
>>
>> Disabling only pairwise keys helps. Disabling only shared keys does
>> not help.
>>
>> Not sure if this will be helpful information or make things more
>> confusing, but seems the difference between mt76_txq_schedule()
>> and tasklet_schedule() in mt76_wake_tx_queue() is that on
>> mt76_txq_schedule() some tx packets are serialized by dev->rx_lock
>> (because some ARP and TCP packets are sent via network stack as response
>> of incoming packet within ieee80211_rx_napi() call). Removing
>> spin_lock(&dev->rx_lock) in mt76_rx_complete() make the problem
>> reproducible again with mt76_txq_schedule() & HW encryption.
>
> So, I think this is FW/HW issue related with encryption and ordering
> and we should apply patch originally posted in this thread that
> disable HW encryption for MT7630E.
>
> I do not think we should disable HW encryption only for pairwise keys,
> because FW/HW can have the same bug for shared keys, but is not
> triggered in my test, as we do not sent lot of group frames.
I'm still not convinced that this is just the hardware implementation of
hw crypto being faulty. I think it's more likely that there's a bug in
the tx path somewhere, which causes hangs on MT7630E but remains hidden
(or at least recoverable) on other devices.
I'm currently reviewing key handling in the mac80211 fast-xmit codepath
and get the feeling that something might be racy there.
I will let you know when I make some progress with that review.
If we can't find the bug soon, then I'm fine with merging this patch.
Right now, I would like to see first if we can fix it properly.
- Felix
next prev parent reply other threads:[~2019-08-21 9:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 13:36 [PATCH 5.3] mt76: mt76x0e: don't use hw encryption for MT7630E Stanislaw Gruszka
2019-08-14 9:50 ` Lorenzo Bianconi
2019-08-15 10:09 ` Stanislaw Gruszka
2019-08-15 10:20 ` Felix Fietkau
2019-08-19 11:06 ` Stanislaw Gruszka
2019-08-20 10:31 ` Felix Fietkau
2019-08-20 11:24 ` Stanislaw Gruszka
2019-08-21 8:47 ` Stanislaw Gruszka
2019-08-21 9:03 ` Felix Fietkau [this message]
2019-08-21 10:40 ` Felix Fietkau
2019-08-21 11:22 ` Stanislaw Gruszka
2019-08-22 7:23 ` Felix Fietkau
2019-09-03 13:49 ` Kalle Valo
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