Re: [RFC][PATCH 5/7] irq_work, smp: Allow irq_work on call_single_queue

[Peter Zijlstra]

On Fri, Jun 05, 2020 at 05:02:08PM +0200, Frederic Weisbecker wrote:
> On Fri, Jun 05, 2020 at 11:37:04AM +0200, Peter Zijlstra wrote:
> >  struct irq_work {
> > -	struct llist_node llnode;
> > -	atomic_t flags;
> > +	union {
> > +		struct __call_single_node node;
> > +		struct {
> > +			struct llist_node llnode;
> > +			atomic_t flags;
> > +		};
> > +	};
> 
> So why not just embed struct __call_single_node in
> struct irq_work and struct __call_single_data ?
> 
> Is the point of that anonymous second union layer to
> shorten the lines while accessing members?

To cut down on all the churn. irq_work is small and could easily be
fixed up, but csd is used in quite a few places.