[PATCH 1/2] lib: Provide generic atomic64_t implementation

[Paul Mackerras]

Mike Frysinger writes:

> On Sat, Jun 13, 2009 at 03:10, Paul Mackerras wrote:
> > +typedef struct {
> > +       long long counter;
> > +} atomic64_t;
> 
> lack of volatile seems odd compared to:
> include/linux/types.h:
> typedef struct {
>     volatile int counter;
> } atomic_t;
> -mike

It's only accessed under a spinlock, so I don't think it needs to be
volatile.  On UP it's accessed within local_irq_save/restore which
should also be compiler barriers and prevent memory access reordering,
so again volatile isn't needed.

Paul.