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Date:   Tue, 12 Nov 2019 07:24:18 -0700
From:   Jerry Snitselaar <jsnitsel@redhat.com>
To:     Stefan Berger <stefanb@linux.ibm.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: question about setting TPM_CHIP_FLAG_IRQ in tpm_tis_core_init
Message-ID: <20191112142418.3wwa4iukas4h2glp@cantor>
Reply-To: Jerry Snitselaar <jsnitsel@redhat.com>
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        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue Nov 12 19, Stefan Berger wrote:
>On 11/11/19 10:36 PM, Jerry Snitselaar wrote:
>>Question about 1ea32c83c699 ("tpm_tis_core: Set TPM_CHIP_FLAG_IRQ=20
>>before probing for interrupts").
>>Doesn't tpm_tis_send set this flag, and setting it here in=20
>>tpm_tis_core_init short circuits what
>>tpm_tis_send was doing before? There is a bug report of an interrupt=20
>>storm from a tpm on a t490s laptop
>>with the Fedora 31 kernel (5.3), and I'm wondering if this change=20
>>could cause that. Before they got
>>the warning about interrupts not working, and using polling instead.
>>
>I set this flag for the TIS because it wasn't set anywhere else.=20
>tpm_tis_send() wouldn't set the flag but go via the path:
>
>if (!(chip->flags & TPM_CHIP_FLAG_IRQ) || priv->irq_tested)
>
>=A0=A0=A0=A0=A0=A0=A0 return tpm_tis_send_main(chip, buf, len);
>
>the only other line for the TIS to set the IRQ flag was in the same=20
>function further below, though that wouldn't be reached due to the=20
>above:
>
>[...]
>
>priv->irq =3D irq;
>
>chip->flags |=3D TPM_CHIP_FLAG_IRQ;
>
>
>=A0=A0 Stefan
>
>

Ugh, you're right I was reading that as ! around both the flag and priv->ir=
q_tested.

Should the flag be cleared if tpm_tis_probe_irq_single fails prior to calli=
ng
tpm_tis_gen_interrupt?