Date: Mon, 11 Jun 2018 22:46:34 +0200
From: Michael =?UTF-8?B?QsO8c2No?= <m@bues.ch>
To: Wirz <spam@lukas-wirz.de>
Cc: b43-dev@lists.infradead.org,
        linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: b43 crashes on rmmod (bcm4331)
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On Mon, 11 Jun 2018 23:09:06 +0300
Wirz <spam@lukas-wirz.de> wrote:

> the bisection leads to
>=20
> 142a27f0a731ddcf467546960a5585970ca98e21 is the first bad commit
> commit 142a27f0a731ddcf467546960a5585970ca98e21
> Author: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
> Date:   Fri Oct 27 22:34:04 2017 +0530
>=20
>     hwrng: core - Reset user selected rng by writing "" to rng_current
>=20
>     User is able to select a chosen rng by writing its name to rng_current
>     but there is no way to reset it without unbinding the rng. Let user
>     write "" to rng_current and delesect the chosen rng.
>=20
>     Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
>     reviewed-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
>     Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>=20
> :040000 040000 f61e5cc501c99fb09bae5f203528b9f4c3479f8a
> 785262813cfb02c9606fd72274f0f7b44f2289d7 M	drivers


Thanks a lot for bisecting this.

This commit introduces a bug, if b43 is the only RNG in the system. But
that is unlikely on modern systems and it's fixed by
0e4b52942b1c76f89e0dcb829f72e123d0678f54, which is in 4.16.

Other than that I currently can't see why this crashes.

But the crash should go away, if you disable CONFIG_B43_HWRNG.
That's not a solution, but it may help, if you would like to get rid of
the crashes.
Could you please verify whether disabling CONFIG_B43_HWRNG avoids the
crash, just to make sure we are not after a red herring here?

Thanks.

--=20
Michael

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