linux-kernel - Re: [PATCH 9/9] random: simplify accounting code

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Message-ID: <20131206182503.GK8043@ringworld.MIT.EDU>
Date:	Fri, 6 Dec 2013 13:25:04 -0500
From:	Greg Price <price@....EDU>
To:	"Theodore Ts'o" <tytso@....edu>, linux-kernel@...r.kernel.org,
	Jiri Kosina <jkosina@...e.cz>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 9/9] random: simplify accounting code

On Thu, Dec 05, 2013 at 08:13:47PM -0500, Theodore Ts'o wrote:
> On Wed, Nov 13, 2013 at 03:08:41AM -0500, Greg Price wrote:
> > +	if (ibytes && cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
> > +		goto retry;
> 
> I wonder if we would be better dropping the test for ibytes here, so
> the above condition reads:
> 
> 	if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
> 		goto retry;
> 
> It further simplifies the code, and it means that if we it turns out
> that ibytes is zero (meaning there was no entropy available) but some
> additional entropy comes in, we might acutally end up retrying and
> successfully grabbing that entropy for the caller.

Sure, that'd be reasonable.  I didn't do that mainly because I wanted
to preserve existing behavior wherever possible in these cleanups, to
make them easy to read and review.

Greg

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