Re: [PATCH] [char] random: fix priming of last_data

From: Jarod Wilson
Date: Tue Mar 19 2013 - 13:12:29 EST

On Tue, Mar 19, 2013 at 12:18:09PM -0400, Jarod Wilson wrote:
> Commit ec8f02da9e added priming of last_data per fips requirements.
> Unfortuantely, it did so in a way that can lead to multiple threads all
> incrementing nbytes, but only one actually doing anything with the extra
> data, which leads to some fun random corruption and panics.
> The fix is to simply do everything needed to prime last_data in a single
> shot, so there's no window for multiple cpus to increment nbytes -- in
> fact, we won't even increment or decrement nbytes anymore, we'll just
> extract the needed EXTRACT_BYTES one time per pool and then carry on with

Error in the description, if anyone actually cares. Oops.

> the normal routine.
> All these changes have been tested across multiple hosts and architectures
> where panics were previously encoutered. The code changes are are strictly
> limited to areas only touched when when booted in fips mode.
> This change should also go into 3.8-stable, to make the myriads of fips
> users on 3.8.x happy.

Jarod Wilson

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