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From:   Valentin Schneider <vschneid@redhat.com>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     linux-wireless <linux-wireless@vger.kernel.org>,
        Kalle Valo <kvalo@kernel.org>,
        Rui Salvaterra <rsalvaterra@gmail.com>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        stable <stable@vger.kernel.org>,
        Gregory Erwin <gregerwin256@gmail.com>,
        Toke =?utf-8?Q?H=C3=B8iland-J?= =?utf-8?Q?=C3=B8rgensen?= 
        <toke@toke.dk>, Herbert Xu <herbert@gondor.apana.org.au>
Subject: Re: [PATCH v10] ath9k: let sleep be interrupted when unregistering
 hwrng
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Date:   Mon, 25 Jul 2022 11:08:58 +0100
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Hi Jason,

On 22/07/22 22:13, Jason A. Donenfeld wrote:
> Hi Valentin,
>
> On Fri, Jul 22, 2022 at 10:09 PM Valentin Schneider <vschneid@redhat.com> wrote:
>> I had initially convinced myself this would be somewhat involved, but
>> writing the above I thought maybe not... The below is applied on top of
>> your v10, would you be able to test whether it actually works?
>> It does however mean patching up any sleeping hwrng (a quick search tells
>> me there are more, e.g. npcm-rng does readb_poll_timeout())
>
> I'm not able to test this easily, no (I don't own any hardware), and
> I'm not going to put in the effort to rewrite/audit every sleeping
> hwrng. That's not a good use of time, given the numerous other
> problems the framework has (briefly discussed with Eric). Instead,
> maybe at some point I'll look into overhauling all of this so that
> none of this will be required anyway. So I think v10 is my final
> submission on this.
>

I think that's fair, I hope I didn't discourage you too much from
contributing in that area.

> But if you'd like to attempt more comprehensive changes throughout the
> tree on all the drivers and do something large, I guess you can do
> that independently (since you mentioned your thing works on top of
> v10). And this way v10 still exists to fix the actual bug that's
> currently reeking havoc. On the other hand, maybe don't bother, and we
> can look into fixing the whole rats nest properly in some months when
> I'm more motivated to jump into hwrng.
>

Just to make sure I'm on the same page as you - is your patch solely for
ath9k, or is it supposed to fix other drivers?

AFAICT your changes to hw_random/core.c work with any hwnrg driver that
does a variant of schedule_timeout() during rng_get_data(), whereas what I
suggested only works for "opted-in" drivers (just ath9k ATM), but it
doesn't break the other drivers in any way.

So if ath9k is widely used / a problem for lots of folks, we could just fix
that one and leave the others TBD. What do you think?