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

From: James Bottomley
Date: Tue May 26 2020 - 20:18:26 EST


On Tue, 2020-05-26 at 16:31 -0700, Alex Guzman wrote:
> On Tue, May 26, 2020 at 4:06 PM James Bottomley
> <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> 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.

Sorry, that's likely my fault: I did it on top of my current TPM tree.
I'll prepare a version against the vanilla kernel with a real
changelog.

> 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. :)

Great, thanks! I'll add your tested-by to the above.

James