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Date:   Wed, 24 May 2023 18:30:27 +0300
Message-Id: <CSUM65JDEX5D.8GL20PUI2XDV@suppilovahvero>
Cc:     <jsnitsel@redhat.com>, <hdegoede@redhat.com>,
        <oe-lkp@lists.linux.dev>, <lkp@intel.com>,
        <peter.ujfalusi@linux.intel.com>, <peterz@infradead.org>,
        <linux@mniewoehner.de>, <linux-integrity@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <l.sanfilippo@kunbus.com>,
        <lukas@wunner.de>, <p.rosenberger@kunbus.com>
Subject: Re: [PATCH 1/2] tpm, tpm_tis: Handle interrupt storm
From:   "Jarkko Sakkinen" <jarkko@kernel.org>
To:     "Jarkko Sakkinen" <jarkko@kernel.org>,
        "Lino Sanfilippo" <LinoSanfilippo@gmx.de>, <peterhuewe@gmx.de>,
        <jgg@ziepe.ca>
References: <20230522143105.8617-1-LinoSanfilippo@gmx.de>
 <CSU7G2UZSZ8K.22EGXU5CJTZBB@suppilovahvero>
In-Reply-To: <CSU7G2UZSZ8K.22EGXU5CJTZBB@suppilovahvero>
Precedence: bulk

On Wed May 24, 2023 at 6:58 AM EEST, Jarkko Sakkinen wrote:
> >  	rc =3D tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrup=
t);
> >  	if (rc < 0)
> > -		return IRQ_NONE;
> > +		goto unhandled;
> > =20
> >  	if (interrupt =3D=3D 0)
> > -		return IRQ_NONE;
> > +		goto unhandled;
> > =20
> >  	set_bit(TPM_TIS_IRQ_TESTED, &priv->flags);
> >  	if (interrupt & TPM_INTF_DATA_AVAIL_INT)
> > @@ -780,10 +829,14 @@ static irqreturn_t tis_int_handler(int dummy, voi=
d *dev_id)
> >  	rc =3D tpm_tis_write32(priv, TPM_INT_STATUS(priv->locality), interrup=
t);
> >  	tpm_tis_relinquish_locality(chip, 0);
> >  	if (rc < 0)
> > -		return IRQ_NONE;
> > +		goto unhandled;
> > =20
> >  	tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &interrupt);
> >  	return IRQ_HANDLED;
> > +
> > +unhandled:
> > +	tpm_tis_process_unhandled_interrupt(chip);
> > +	return IRQ_HANDLED;
> >  }

Some minor glitches I noticed.

You could simplify the flow by making the helper to return IRQ_NONE.

E.g.=20

	tpm_tis_relinquish_locality(chip, 0);
	if (rc < 0)
		return tpm_tis_process_unhandled_interrupt(chip);

I'd recommend changing the function name simply tpm_tis_rollback_interrupt(=
).

Also tpm_tis_handle_irq_storm() is a pretty bad function name=20
because handle also can mean anything. You are resetting to the
polling mode, right?

So perhaps that could be e.g. tpm_tis_reenable_polling? I'm open
for any other name but it really needs to give a hint what the
function does.

BR, Jarkko