Re: [PATCH 10/19] workqueue: update cwq alignement and make onemore flag bit available

[Alan Cox]

On Thu, 01 Oct 2009 14:05:20 +0100
David Howells <dhowells@xxxxxxxxxx> wrote:

> Tejun Heo <tj@xxxxxxxxxx> wrote:
> 
> > +enum {
> > +	WORK_STRUCT_PENDING	= 0,	/* work item is pending execution */
> > +
> > +	/*
> > +	 * Reserve 3bits off of cwq pointer.  This is enough and
> > +	 * provides acceptable alignment on both 32 and 64bit
> > +	 * machines.
> > +	 */
> > +	WORK_STRUCT_FLAG_BITS	= 3,
> > +
> > +	WORK_STRUCT_FLAG_MASK	= (1UL << WORK_STRUCT_FLAG_BITS) - 1,
> > +	WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
> > +};
> 
> There's some great enum abuse going on here:-)

Its actually a very sensible use of enum - enum constants don't contain
the deathtraps that CPP constants do.

Alan
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