Re: [dpdk-dev] [PATCH v3 01/15] eal: introduce atomic exchange operation

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 11 Jan 2018 17:01:10 +0000
Ferruh Yigit <ferruh.yigit@intel.com> wrote:

> On 1/8/2018 5:45 PM, Stephen Hemminger wrote:
> > To handle atomic update of link status (64 bit), every driver
> > was doing its own version using cmpset.
> > Atomic exchange is a useful primitive in its own right;
> > therefore make it a EAL routine.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>  
> 
> <...>
> 
> > @@ -98,6 +98,18 @@ rte_atomic64_cmpset(volatile uint64_t *dst, uint64_t exp, uint64_t src)
> >  	return res;
> >  }
> >  
> > +static inline uint64_t
> > +rte_atomic64_exchange(volatile uint64_t *dest, uint64_t val)
> > +{
> > +	uint64_t old;
> > +
> > +	do {
> > +		old = *dest;
> > +	} while (rte_atomic64_t_cmpset(dest, old, val));  
> 
> rte_atomic64_cmpset ? (without _t)
> 
> > +
> > +	return old;
> > +}  
> 
> <...>
> 

Addressed in followup patch, needed to build on 32bit.

Will fold into next version.