linux-kernel - Re: [tpmdd-devel] [PATCH 09/13] tpm: Pull everything related to sysfs into tpm-sysfs.c

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Message-ID: <20130923193633.GA9194@obsidianresearch.com>
Date:	Mon, 23 Sep 2013 13:36:33 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Daniel De Graaf <dgdegra@...ho.nsa.gov>
Cc:	tpmdd-devel@...ts.sourceforge.net,
	Leonidas Da Silva Barbosa <leosilva@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, Rajiv Andrade <mail@...jiv.net>,
	Sirrix AG <tpmdd@...rix.com>
Subject: Re: [tpmdd-devel] [PATCH 09/13] tpm: Pull everything related to
 sysfs into tpm-sysfs.c

On Mon, Sep 23, 2013 at 02:54:21PM -0400, Daniel De Graaf wrote:
> On 09/23/2013 02:14 PM, Jason Gunthorpe wrote:
> >CLASS-sysfs.c is a common idiom for linux subsystems.
> >
> >This pulls all the sysfs attribute functions and related code
> >into tpm-sysfs.c. To support this change some constants are moved
> >from tpm.c to tpm.h and __tpm_pcr_read is made non-static and is
> >called tpm_pcr_read_dev.
> >
> >Signed-off-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
> [...]
> >diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
> >index 12a4ab2..7892557 100644
> >+++ b/drivers/char/tpm/xen-tpmfront.c
> [...]
> >-static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
> >-static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
> >-static DEVICE_ATTR(locality, S_IRUGO | S_IWUSR, tpm_show_locality,
> >-		tpm_store_locality);
> 
> This patch drops the "locality" sysfs attribute from xen-tpmfront. Since
> that attribute is currently only implemented for the xen TPM driver, it
> is best to leave it there for now (and its show/store functions could
> also be made static, an oversight I just noticed now). If this attribute
> is later made available on other TPM drivers, it may need to contain
> device-specific logic, but such an implementation is well outside the
> scope of this series.

Okay, I see what you are talking about, the compiler didn't warn
because of the missing static.

This really is a core functionality. Lots of other drivers support
locality, but none have dared actually expose the functionality. IHMO,
it is a mistake to just jam a locality attribute in one driver.

Sorry, I would have said something when the driver was posted if it
was obvious this was hiding in there :|

It looks like this driver was introduced in the 3.12 merge window, we
could drop the attribute, and try to merge a core supported locality
API in 3.13? What do you think?

But, if you say it is needed, it is easy enough to adjust this patch
series.

Thanks,
Jason
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