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From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH] ppp: add 64 bit stats
Date: Tue, 24 Jul 2012 08:22:34 +0200
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On Mon, 2012-07-23 at 21:53 -0400, Kevin Groeneveld wrote:
> On Mon, Jul 23, 2012 at 11:59 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >> Would proper synchronization in this case just be wrapping the updates
> >> in a spin_lock/spin_unlock?
> >
> > Would be fine (if the proper BH safe variant is used), or you could also
> > use atomic64_t.
> 
> Which would you recommend, spin locks or atomic64_t?
> 
> atomic64_t seems like it would be simpler.

Simpler but a bit more expensive when two counters are changed at the
same time.

(two atomic ops instead of a single one for the spinlock)