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Subject: Re: pull-request: mac80211 2021-01-18.2
To:     "Peer, Ilan" <ilan.peer@intel.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        "Coelho, Luciano" <luciano.coelho@intel.com>
References: <20210118204750.7243-1-johannes@sipsolutions.net>
 <77c606d4-a78a-1fa3-5937-b270c3d0bbd3@redhat.com>
 <b83f6cf001c4e3df97eeaed710b34fda0a08265f.camel@sipsolutions.net>
 <BN7PR11MB2610052E380E676ED5CCCC67E9BE9@BN7PR11MB2610.namprd11.prod.outlook.com>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <348210d8-6940-ca8d-e3b1-f049330a2087@redhat.com>
Date:   Sun, 24 Jan 2021 11:54:39 +0100
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Hi,

On 1/24/21 10:12 AM, Peer, Ilan wrote:
>> -----Original Message-----
>> From: Johannes Berg <johannes@sipsolutions.net>
>> Sent: Sunday, January 24, 2021 00:16
>> To: Hans de Goede <hdegoede@redhat.com>; netdev@vger.kernel.org
>> Cc: linux-wireless@vger.kernel.org; Peer, Ilan <ilan.peer@intel.com>;
>> Coelho, Luciano <luciano.coelho@intel.com>
>> Subject: Re: pull-request: mac80211 2021-01-18.2
>>
>> On Sat, 2021-01-23 at 22:31 +0100, Hans de Goede wrote:
>>>
>>> So I'm afraid that I have some bad news about this patch, it fixes the
>>> RCU warning which I reported:
>>>
>>> https://lore.kernel.org/linux-wireless/20210104170713.66956-1-hdegoede
>>> @redhat.com/
>>>
>>> But it introduces a deadlock. See:
>>>
>>> https://lore.kernel.org/linux-wireless/d839ab62-e4bc-56f0-d861-f172bf1
>>> 9c4b3@redhat.com/
>>>
>>> for details. Note we really should fix this new deadlock before 5.11
>>> is released. This is worse then the RCU warning which this patch fixes.
>>
>> Ouch. Thanks for the heads-up. I guess I'll revert both patches for now,
>> unless we can quickly figure out a way to get all these paths in order.
>>
> 
> Thanks Hans and Johannes for handling this. I'll try to come up with a solution.

Great, thank you for looking into this. Let me know if you have a patch
which you want me to test on a RTL8723BS adapter.

One thing which I forgot to mention earlier, it is not just lockdep complaining
this appears to be a real deadlock, the wifi no longer functions, where
as it does function with the patch drops.

Regards,

Hans