linux-kernel - Re: [GIT PULL] New TPM driver, hwrng driver and fixes

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Message-ID: <20120727193654.GA11027@linux.vnet.ibm.com>
Date:	Fri, 27 Jul 2012 14:36:54 -0500
From:	Kent Yoder <key@...ux.vnet.ibm.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	James Morris <jmorris@...ei.org>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	tpmdd-devel@...ts.sourceforge.net,
	Peter Huewe <peter.huewe@...ineon.com>,
	Bryan Freed <bfreed@...omium.org>
Subject: Re: [GIT PULL] New TPM driver, hwrng driver and fixes


> Since you no longer modify *max anywhere in this function, why leave it
> a pointer?  Making it pass by value seems more logical at that point
> (and cleaner).
> 
> The only consumer which can make use of partial result is
> tpm_rng_read(), but that will now return zero unless the buffer is filled.
> 
> My suggestion would be to drop the pointer and instead return a positive
> result (number of bytes) if you read anything and a negative result
> (-errno) on error.

  Sounds good.  I'll make this change.

Kent

> That way, a caller which can only use an exact number of bytes should do:
> 
> 	rv = tpm_get_random(chip, buf, size);
> 	if (rv != size)
> 		/* error! */
> 
> ... and tpm_rng_read() can do something smarter.
> 
> 	-hpa
> 

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