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 15:58:00 +0200 [thread overview]
Message-ID: <20181119135800.GE8755@linux.intel.com> (raw)
In-Reply-To: <90072f09-6388-b1f7-387b-42f056f8893d@intel.com>
On Sun, Nov 18, 2018 at 07:05:19PM -0800, Tadeusz Struk wrote:
> > When ret_size < 0? Shouldn't this be just "if (!ret_size)"?
>
> What we want to check here is if ret_size is positive, which is a valid
> value, or if it is negative or zero, which is an invalid value, so in
> this case (!ret_size) will not work.
Please explain a scenario where "!ret_size" would no work given that
both size and partial_data have always positive value?
> >> /* Holds the resul of the last successful call to tpm_transmit() */
> >> size_t transmit_result;
> >> + /* Holds the count how much of the response is still unread */
> >> + size_t partial_data;
> > I'm otherwise happy how this look like but why call it partial_data.
> > You cannot really tell from the name anything about its contents as
> > data is very abstract term.
>
> so I will rename these two to response_length and response_length_rem,
> how does this sound?
Yes, assuming that there would be a hard requirement to even have two
variables in the first place.
> > BTW, why you need the new variable anyway and not just decrease the
> > variable where the length is original stored?
>
> We need to have two variables, otherwise how do we tell if some part of
> response was consumed to allow sending a new command?
I don't understand. In order to maintain backwards compatibility you can
send a new command at any time.
> The transmit_result is used for that. If it is zero then one can transmit
> a new command even if the whole response is not consumed. The new variable
> tracks how much of the response is still to be read.
AFAIK you only need to track the latter, not both.
/Jarkko
next prev parent reply other threads:[~2018-11-19 13:58 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 [this message]
2018-11-19 16:44 ` Tadeusz Struk
2018-11-19 17:28 ` Jarkko Sakkinen
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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