From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: jgg@ziepe.ca, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] tpm: add support for partial reads
Date: Mon, 19 Nov 2018 19:28:24 +0200 [thread overview]
Message-ID: <20181119172824.GB16252@linux.intel.com> (raw)
In-Reply-To: <b0efbbf8-6242-a48d-d984-b49d5fb20bb8@intel.com>
On Mon, Nov 19, 2018 at 08:44:49AM -0800, Tadeusz Struk wrote:
> On 11/19/18 5:58 AM, Jarkko Sakkinen wrote:
> > Please explain a scenario where "!ret_size" would no work given that
> > both size and partial_data have always positive value?
>
> Right, I only looked at the one line above before responding.
> I'll change it to !ret_size
>
> >
> > I don't understand. In order to maintain backwards compatibility you can
> > send a new command at any time.
>
> No, currently it is not possible to send a new command until the previous
> response is consumed. -EBUSY is returned if one sends a new command before
> reading the previous response (or at least part of it). See:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/tpm/tpm-dev-common.c#n128
Ah, you are correct.
You should add a boolean flag instead of introducing a new variable for
holding amount that has been read because obviously one read operation
is enough for backwards compatibility.
The code could read the code to data_pending and then set
priv->data_read = false;
We do not need the original amount for anything.
/Jarkko
next prev parent reply other threads:[~2018-11-19 17:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-16 17:51 [PATCH 1/2] tpm: rename data_pending to transmit_result Tadeusz Struk
2018-11-16 17:51 ` [PATCH v4 2/2] tpm: add support for partial reads Tadeusz Struk
2018-11-18 7:48 ` Jarkko Sakkinen
2018-11-19 3:05 ` Tadeusz Struk
2018-11-19 13:58 ` Jarkko Sakkinen
2018-11-19 16:44 ` Tadeusz Struk
2018-11-19 17:28 ` Jarkko Sakkinen [this message]
2018-11-19 17:43 ` Tadeusz Struk
2018-11-18 7:41 ` [PATCH 1/2] tpm: rename data_pending to transmit_result Jarkko Sakkinen
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