From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ursula Braun Subject: Re: [PATCH RESEND net-next 13/15] smc: receive data from RMBE Date: Fri, 2 Sep 2016 15:05:01 +0200 Message-ID: <7121effc-5f89-ac22-bbab-a8aedebae9fd@linux.vnet.ibm.com> References: <1470737580-43012-14-git-send-email-ubraun@linux.vnet.ibm.com> <20160809.143245.2022037008405834176.davem@davemloft.net> <653f839a-8098-da62-3437-8b002d929a50@linux.vnet.ibm.com> <20160810.104556.1507709019319192063.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160810.104556.1507709019319192063.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Archive: List-Post: To: David Miller Cc: netdev@vger.kernel.org, linux-s390@vger.kernel.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, utz.bacher@de.ibm.com List-ID: Dave, sorry for the late answer; I had to interrupt my SMC-R activities for a while; now I can continue ... On 08/10/2016 07:45 PM, David Miller wrote: > From: Ursula Braun > Date: Wed, 10 Aug 2016 15:44:00 +0200 > >> But there are still usages (and conn->rx_curs_confirmed is one of >> them), where I need an 8-byte cursor field to be read and written >> atomicaly, even though I do not care whether the write operation has >> been beaten or not. But I do care that reading the cursor does not >> return a partially updated cursor. Isn't xchg() a possible solution >> in this case? > > Either the cpu supports 64-bit stores or it does not. > > xchg() and atomicity have absolutely nothing to do with this. > Understood, I wrongly used xchg() for atomicity. I now realize that I would need cursor locking for 32-bit architectures - something I would like to defer. Thus I would like to come up with V2 of SMC-R with builds restricted to 64-bit architectures only, and thus no usage of xchg() anymore.