linux-kernel - Re: [REGRESSION] suspend to ram fails in 6.2-rc1 due to tpm errors

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Date:   Thu, 29 Dec 2022 05:16:59 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     James Bottomley <James.Bottomley@...senPartnership.com>
Cc:     Vlastimil Babka <vbabka@...e.cz>, Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>, Jan Dabros <jsd@...ihalf.com>,
        regressions@...ts.linux.dev, LKML <linux-kernel@...r.kernel.org>,
        linux-integrity@...r.kernel.org,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [REGRESSION] suspend to ram fails in 6.2-rc1 due to tpm errors

On Thu, Dec 29, 2022 at 05:03:44AM +0100, Jason A. Donenfeld wrote:
> I recall seeing something pretty similar to this report with the
> selftest as well. Basically, the call to tpm1_do_selftest can race with
> the call to tpm1_get_random, presumably because tpm1_get_random doesn't
> do any locking on its own. So it might be a good idea to make sure that
> tpm1_get_random() isn't running before tpm1_do_selftest() or any other
> TPM commands run.

The other locking angle is that tpm1_pm_suspend() should wait for
tpm1_get_random() to finish or cancel tpm1_get_random(), if that's not
already happening. IIRC, the selftest gets tripped up when it's
triggered on resume due to an already in-flight tpm1_get_random() from
prior to sleep, that never completed.