From: Herbert Xu <herbert@gondor.apana.org.au>
To: Harald Freudenberger <hfreude@linux.vnet.ibm.com>
Cc: linux-crypto@vger.kernel.org,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Ingo Tuchscherer <ingo.tuchscherer@linux.vnet.ibm.com>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>
Subject: Re: [PATCH] s390/crypto: fix aes ctr concurrency issue
Date: Fri, 29 Nov 2013 09:50:23 +0800 [thread overview]
Message-ID: <20131129015023.GA5381@gondor.apana.org.au> (raw)
In-Reply-To: <1385653183.3131.14.camel@myubuntu10>
On Thu, Nov 28, 2013 at 04:39:43PM +0100, Harald Freudenberger wrote:
>
> > You can't use mutex_lock because you may be in a non-sleepable
> > context. Perhaps just fall back to doing it block-by-block, like
> > we do in aesni-intel on x86?
>
> The first attempt to lock the mutex is done with mutex_trylock() which
> should be safe for non-sleepable context. If this fails, an attempt is
> made to allocate a fresh page __get_free_page(GFP_ATOMIC). If this also
> fails, well what could be done then ? I think, it is valid to wait for
> the preallocated page to get released with an mutex_lock(). Should I
> really add code here for handling the 3rd level of the exceptional
> path ?
If it's wrong per se, how does hiding it behind two if's make it
OK?
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2013-11-29 1:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 10:22 [PATCH] s390/crypto: fix aes ctr concurrency issue Harald Freudenberger
2013-11-19 10:22 ` Harald Freudenberger
2013-11-28 14:00 ` Herbert Xu
2013-11-28 15:39 ` Harald Freudenberger
2013-11-29 1:50 ` Herbert Xu [this message]
2013-11-29 8:58 ` Harald Freudenberger
2013-11-22 13:58 ` Gerald Schaefer
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