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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH RESEND net-next 13/15] smc: receive data from RMBE
Date: Wed, 10 Aug 2016 10:45:56 -0700 (PDT)
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From: Ursula Braun <ubraun@linux.vnet.ibm.com>
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.