On Thu, 2019-01-03 at 14:59 +0200, Jarkko Sakkinen wrote:
> On Mon, Dec 31, 2018 at 10:27:31AM -0800, James Bottomley wrote:
> > Ever since 627448e85c766 "tpm: separate cmd_ready/go_idle from
> > runtime_pm" we have been returning success from tpm_try_transmit()
> > even if an error occurred. The reason is that the introduction of
> > rc
> > = tpm_go_idle() at the end of processing overwrites the value of rc
> > if
> > it contains an error code (mostly with success). Fix this by
> > writing
> > the return to a new variable rc1 instead.
> >
> > Fixes: 627448e85c766 "tpm: separate cmd_ready/go_idle from
> > runtime_pm"
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.c
> > om>
> >
> > ---
> >
> > Note: the goto out looks fishy as well. The only go_idle
> > implementor
> > is tpm_crb and that can return a timeout as -ETIME, so it looks
> > like it
> > would then loop forever
> >
> > diff --git a/drivers/char/tpm/tpm-interface.c
> > b/drivers/char/tpm/tpm-interface.c
> > index 129f640424b7..ac7ebab6140c 100644
> > --- a/drivers/char/tpm/tpm-interface.c
> > +++ b/drivers/char/tpm/tpm-interface.c
> > @@ -432,7 +432,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> > *chip,
> > unsigned int flags)
> > {
> > struct tpm_output_header *header = (void *)buf;
> > - int rc;
> > + int rc, rc1;
> > ssize_t len = 0;
> > u32 count, ordinal;
> > unsigned long stop;
> > @@ -547,8 +547,8 @@ static ssize_t tpm_try_transmit(struct tpm_chip
> > *chip,
> > dev_err(&chip->dev, "tpm2_commit_space: error
> > %d\n", rc);
> >
> > out:
> > - rc = tpm_go_idle(chip, flags);
> > - if (rc)
> > + rc1 = tpm_go_idle(chip, flags);
> > + if (rc1)
> > goto out;
> >
> > if (need_locality)
>
> Thanks James and sorry for latency (holiday season). Just a small
> suggestion. I would just:
>
> if (tpm_go_idle(chip, flags))
> goto out;
>
> What do you think?
That it doesn't solve the loop forever with no warning problem. If
anything, I think the correct thing is probably
rc1 = tpm_go_idle(chip, flags);
if (rc1)
dev_err(&chip->dev, "go idle failed with %d\n", rc1);
so we log the problem and move on. If it is a timeout, it will likely
show up on the next TPM operation. Since this is the only caller of
tpm_go_idle(), I think all looping should be done inside that function,
but we should probably wait for Tomas to comment since he wrote it.
James
