linux-kernel - Re: [PATCH v2] crypto: remove instance when test failed

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Message-ID: <12421064.DcDv9fIrjP@tachyon.chronox.de>
Date:	Fri, 03 Apr 2015 21:29:44 +0200
From:	Stephan Mueller <smueller@...onox.de>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] crypto: remove instance when test failed

Am Freitag, 3. April 2015, 23:52:46 schrieb Herbert Xu:

Hi Herbert,

> On Fri, Apr 03, 2015 at 05:17:13PM +0200, Stephan Mueller wrote:
> > Wpuldn't crypto_del_alg suffer from the same issue? I see that the
> > cra_refcnt is checked. But I guess there would be the same kind of race?
> 
> You're quite right.  It too needs to take a ref count on the
> algorithm in crypto_alg_match before releasing the mutex.
> 

What about moving the current crypto_unregister_instance into 
__crypto_unregister_instance and creating a new crypto_unregister_instance 
that takes the ref count and once it got it, it calls 
__crypto_unregister_instance. If it did not get the ref count, it simply 
returns because the inst apparently was already removed.

Only the crypto_unregister_instance is EXPORT_SYMBOL whereas the 
__crypto_unregister_instance is static.

> Cheers,

-- 
Ciao
Stephan
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