Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v3 1/4] tpm: Use a threaded interrupt handler
To:     Jarkko Sakkinen <jarkko@kernel.org>
Cc:     peterhuewe@gmx.de, jgg@ziepe.ca, stefanb@linux.vnet.ibm.com,
        James.Bottomley@hansenpartnership.com, keescook@chromium.org,
        jsnitsel@redhat.com, ml.linux@elloe.vision,
        linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        Stefan Berger <stefanb@linux.ibm.com>
References: <20210501135727.17747-1-LinoSanfilippo@gmx.de>
 <20210501135727.17747-2-LinoSanfilippo@gmx.de> <YJATRNMqzyAprCbL@kernel.org>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
Message-ID: <1364a268-7173-7253-543e-792ff2104e98@gmx.de>
Date:   Wed, 5 May 2021 00:54:37 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <YJATRNMqzyAprCbL@kernel.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
Precedence: bulk


Hi,


On 03.05.21 at 17:14, Jarkko Sakkinen wrote:
> On Sat, May 01, 2021 at 03:57:24PM +0200, Lino Sanfilippo wrote:
>> The interrupt handler uses tpm_tis_read32() and tpm_tis_write32() to ac=
cess
>> the interrupt status register. In case of SPI those accesses are done w=
ith
>> the spi_bus_lock mutex held. This means that the status register cannot
>> be read or written in interrupt context.
>>
>> For this reason request a threaded interrupt handler so that the requir=
ed
>> accesses can be done in process context.
>>
>> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
>> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
>
> No fixes tag.
>
> The short summary scopes now the whole TPM subsystem ("tpm:"), but the f=
ix
> is targetted *only* for tpm_tis_spi. How about "tpm, tpm_tis_spi: Allow =
to
> sleep in the interrupt handler"?
>
> This also changes the semantics tpm_tis_*, not just tpm_tis_spi, which i=
s
> not acceptable. We cannot backport a fix like this.
>
> Probably you should just add a parameter to tpm_tis_core_init() to hint
> that threaded IRQ is required, and then only conditionally do so.
>

Sure, this is doable although to be honest I dont see the issue with also =
the
non-SPI code running in the threaded interrupt handler. The functionality =
should
not change (especially since interrupts are not even working right now) an=
d it would
save us a special treatment of the SPI case.


Regards,
Lino