linux-kernel - Re: [PATCH v9 3/5] crypto: drbg

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Message-ID: <23102012.0an2QbkQix@tachyon.chronox.de>
Date:	Thu, 21 May 2015 08:10:13 +0200
From:	Stephan Mueller <smueller@...onox.de>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	pebolle@...cali.nl, andreas.steffen@...ongswan.org, tytso@....edu,
	sandyinchina@...il.com, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 3/5] crypto: drbg - add async seeding operation

Am Donnerstag, 21. Mai 2015, 05:44:08 schrieb Herbert Xu:

Hi Herbert,

> On Wed, May 20, 2015 at 10:03:45PM +0200, Stephan Mueller wrote:
> >> @@ -1487,6 +1514,7 @@ unlock:
> >   */
> >  
> >  static int drbg_uninstantiate(struct drbg_state *drbg)
> >  {
> > 
> > +	cancel_work_sync(&drbg->seed_work);
> 
> This will just block until the work is done, i.e., until the
> pool is ready.  It's no different to an uninterruptible sleep.
> 
> So either just do an uninterruptible sleep, or allow the async
> seed to fail.
> 
The cancel operation is needed as otherwise my drbg context handle will be 
removed by the crypto API during the sleep. That is the whole reason why 
wait_event_interruptible is used.

So, even when using an uninterruptible sleep, the crypto API has no knowledge 
about it and I have to serialize the destruction code path with the async 
callback.

-- 
Ciao
Stephan
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