Re: [PATCH RESEND net-next 13/15] smc: receive data from RMBE

[Ursula Braun <ubraun@linux.vnet.ibm.com>]

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 <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.
>

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.