linux-kernel - Re: [PATCH] tpm: Revert "tpm: fix invalid locking in NONBLOCKING mode"

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Message-ID: <CAJ7-PMaoFyi89OFgYsNknc2d0Fr4RHLmmHo-puNiKchM=0mU6w@mail.gmail.com>
Date:   Tue, 26 May 2020 16:31:01 -0700
From:   Alex Guzman <alex@...man.io>
To:     James Bottomley <James.Bottomley@...senpartnership.com>
Cc:     Mario Limonciello <Mario.Limonciello@...l.com>,
        Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jeffrin Jose T <jeffrin@...agiritech.edu.in>
Subject: Re: [PATCH] tpm: Revert "tpm: fix invalid locking in NONBLOCKING mode"

On Tue, May 26, 2020 at 4:06 PM James Bottomley
<James.Bottomley@...senpartnership.com> wrote:
>
> On Tue, 2020-05-26 at 15:19 -0700, Alex Guzman wrote:
> [...]
> > When using your patch, I get a hang when trying to use tpm2_getcap,
> > and dmesg shows some info.
>
> Are you sure it's all applied?  This
>
> > [  570.913803]  tpm_tcg_write_bytes+0x2f/0x40
> > [  570.913805]  release_locality+0x49/0x220
> > [  570.913807]  tpm_relinquish_locality+0x1f/0x40
> > [  570.913808]  tpm_chip_stop+0x21/0x40
> > [  570.913810]  tpm_put_ops+0x9/0x30
> > [  570.913811]  tpm_common_write+0x179/0x190
> > [  570.913813]  vfs_write+0xb1/0x1a0
>
> Implies an unmatched tpm_put_ops() in the async write path, as though
> this hunk:
>
> > @@ -211,11 +202,19 @@ ssize_t tpm_common_write(struct file *file,
> > const char __user *buf,
> >         if (file->f_flags & O_NONBLOCK) {
> >                 priv->command_enqueued = true;
> >                 queue_work(tpm_dev_wq, &priv->async_work);
> > -               tpm_put_ops(priv->chip);
> >                 mutex_unlock(&priv->buffer_mutex);
> >                 return size;
> >         }
>
> Is missing.  I actually booted the patch in my TPM based VM and it all
> seems to work OK when I execute tpm2_getcap (I verified it's using
> O_NONBLOCK) and tssgetcapability in sync mode.
>
> James
>

Oh, I did miss that bit. The patch had issues applying for some reason
and I missed the single-line removal when I was looking at the diff.

I gave it a spin on my machine again. getcap seems to work correctly
with and without having the async config flag set for tpm2-tss. The
pkcs11 plugin seems to work correctly again too. :)