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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Fri, 24 Jun 2022 01:47:35 +0200
Message-ID: <CAHmME9otPsJz5WUq_S2NuJFy0RzjUKEaU=4mZx-dAgfJF8P-yQ@mail.gmail.com>
Subject: Re: ath9k: hwrng blocks for several minutes when phy is un-associated
To:     Gregory Erwin <gregerwin256@gmail.com>
Cc:     Rui Salvaterra <rsalvaterra@gmail.com>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        linux-wireless <linux-wireless@vger.kernel.org>
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Hey Gregory,

On Fri, Jun 24, 2022 at 1:36 AM Gregory Erwin <gregerwin256@gmail.com> wrote:
>
> No luck.
>
> The first patch caused a warning and oops with ath9k_rng_read() at the
> top of the call stack when reading from /dev/hwrng:
>   WARNING: CPU: 1 PID: 454 at kernel/kthread.c:75 kthread_should_stop+0x2a/0x30
>   BUG: kernel NULL pointer dereference, address: 0000000000000000
>
> The second didn't have a noticeable effect, for better or worse.

Alright. That's actually getting us somewhere. So the path in question
here is from reading /dev/hwrng, not from the kthread that's doing the
same read.

Can you do a `cat /dev/hwrng > /dev/null`, and then do whatever it is
you do that causes everything to hang, and then while things are hung
in the bad way, look at the contents of /proc/[the pid of the cat you
just ran]/stack?

Jason