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From: Jarkko Sakkinen <jarkko@kernel.org>
To: Lino Sanfilippo <LinoSanfilippo@gmx.de>
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>
Subject: Re: [PATCH v3 1/4] tpm: Use a threaded interrupt handler
Date: Thu, 6 May 2021 04:46:47 +0300	[thread overview]
Message-ID: <YJNKh2HGbURNBter@kernel.org> (raw)
In-Reply-To: <1364a268-7173-7253-543e-792ff2104e98@gmx.de>

On Wed, May 05, 2021 at 12:54:37AM +0200, Lino Sanfilippo wrote:
> 
> 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 access
> >> the interrupt status register. In case of SPI those accesses are done with
> >> 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 required
> >> 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 fix
> > 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 is
> > 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) and it would
> save us a special treatment of the SPI case.

It's violation of "3) Separate your changes" [*].

E.g. we do not want to introduce "improvements" or "simplifications" to
stable kernels on purpose.

[*] https://www.kernel.org/doc/html/v5.11/process/submitting-patches.html> 

/Jarkko

  reply	other threads:[~2021-05-06  1:47 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-01 13:57 [PATCH v3 0/4] Fixes for TPM interrupt handling Lino Sanfilippo
2021-05-01 13:57 ` [PATCH v3 1/4] tpm: Use a threaded interrupt handler Lino Sanfilippo
2021-05-03 15:14   ` Jarkko Sakkinen
2021-05-04 22:54     ` Lino Sanfilippo
2021-05-06  1:46       ` Jarkko Sakkinen [this message]
2021-05-01 13:57 ` [PATCH v3 2/4] tpm: Simplify locality handling Lino Sanfilippo
2021-05-03 15:50   ` Jarkko Sakkinen
2021-05-04 23:15     ` Lino Sanfilippo
2021-05-06  1:47       ` Jarkko Sakkinen
2022-03-24 17:04         ` [PATCH v3 0/4] Fixes for TPM interrupt handling Michael Niewöhner
2022-03-25  2:14           ` Jarkko Sakkinen
2022-03-25 12:32             ` Michael Niewöhner
2022-03-26  3:24               ` Lino Sanfilippo
2022-03-26  8:59                 ` Michael Niewöhner
2022-03-30 15:19                 ` Jarkko Sakkinen
2022-04-20  5:30                 ` Jarkko Sakkinen
2022-04-20  5:32                   ` Jarkko Sakkinen
2022-04-24  2:22                   ` Lino Sanfilippo
2022-04-25 13:57                     ` Jarkko Sakkinen
2022-03-30 15:18               ` Jarkko Sakkinen
2021-05-01 13:57 ` [PATCH v3 3/4] tpm: Fix test for interrupts Lino Sanfilippo
2021-05-03 15:52   ` Jarkko Sakkinen
2021-05-04 23:18     ` Lino Sanfilippo
2021-05-01 13:57 ` [PATCH v3 4/4] tpm: Only enable supported irqs Lino Sanfilippo
2021-05-01 19:09   ` Stefan Berger
2021-05-02  3:15     ` Lino Sanfilippo
2021-05-03 15:52   ` Jarkko Sakkinen

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