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From: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
To: Narayana Prasad Athreya <pathreya@caviumnetworks.com>
Cc: Seth Jennings <sjenning@redhat.com>,
	Mahipal Challa <mahipalreddy2006@gmail.com>,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	linux-crypto@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	pathreya@cavium.com, vnair@cavium.com,
	Mahipal Challa <Mahipal.Challa@cavium.com>,
	Vishnu Nair <Vishnu.Nair@cavium.com>
Subject: Re: [RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support
Date: Wed, 15 Feb 2017 22:12:08 +0000	[thread overview]
Message-ID: <20170215221208.GA820@silv-gc1.ir.intel.com> (raw)
In-Reply-To: <58A45E4A.8080508@caviumnetworks.com>

On Wed, Feb 15, 2017 at 07:27:30PM +0530, Narayana Prasad Athreya wrote:
> > I assume all of these crypto_acomp_[compress|decompress] calls are
> > actually synchronous,
> > not asynchronous as the name suggests.  Otherwise, this would blow up
> > quite spectacularly
> > since all the resources we use in the call get derefed/unmapped below.
> > 
> > Could an async algorithm be implement/used that would break this assumption?
> 
> The callback is set to NULL using acomp_request_set_callback(). This implies
> synchronous mode of operation. So the underlying implementation must
> complete the operation synchronously.
This assumption is not correct. An asynchronous implementation, when
it finishes processing a request, will call acomp_request_complete() which
in turn calls the callback.
If the callback is set to NULL, this function will dereference a NULL
pointer.

Regards,

-- 
Giovanni 

--
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WARNING: multiple messages have this Message-ID (diff)
From: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
To: Narayana Prasad Athreya <pathreya@caviumnetworks.com>
Cc: Seth Jennings <sjenning@redhat.com>,
	Mahipal Challa <mahipalreddy2006@gmail.com>,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	linux-crypto@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	pathreya@cavium.com, vnair@cavium.com,
	Mahipal Challa <Mahipal.Challa@cavium.com>,
	Vishnu Nair <Vishnu.Nair@cavium.com>
Subject: Re: [RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support
Date: Wed, 15 Feb 2017 22:12:08 +0000	[thread overview]
Message-ID: <20170215221208.GA820@silv-gc1.ir.intel.com> (raw)
In-Reply-To: <58A45E4A.8080508@caviumnetworks.com>

On Wed, Feb 15, 2017 at 07:27:30PM +0530, Narayana Prasad Athreya wrote:
> > I assume all of these crypto_acomp_[compress|decompress] calls are
> > actually synchronous,
> > not asynchronous as the name suggests.  Otherwise, this would blow up
> > quite spectacularly
> > since all the resources we use in the call get derefed/unmapped below.
> > 
> > Could an async algorithm be implement/used that would break this assumption?
> 
> The callback is set to NULL using acomp_request_set_callback(). This implies
> synchronous mode of operation. So the underlying implementation must
> complete the operation synchronously.
This assumption is not correct. An asynchronous implementation, when
it finishes processing a request, will call acomp_request_complete() which
in turn calls the callback.
If the callback is set to NULL, this function will dereference a NULL
pointer.

Regards,

-- 
Giovanni 

  reply	other threads:[~2017-02-15 22:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-14 15:40 [RFC PATCH v1 0/1] mm: zswap - crypto acomp/scomp support Mahipal Challa
2017-02-14 15:40 ` Mahipal Challa
2017-02-14 15:40 ` [RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support Mahipal Challa
2017-02-14 15:40   ` Mahipal Challa
2017-02-14 16:20   ` Seth Jennings
2017-02-14 16:20     ` Seth Jennings
2017-02-15 13:57     ` Narayana Prasad Athreya
2017-02-15 13:57       ` Narayana Prasad Athreya
2017-02-15 22:12       ` Giovanni Cabiddu [this message]
2017-02-15 22:12         ` Giovanni Cabiddu
2017-02-20  9:52         ` Nair, Vishnu

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