Re: [TIP][RFC 2/7] futex: futex_top_waiter()

[Darren Hart]

Thomas Gleixner wrote:
> On Mon, 2 Mar 2009, Darren Hart wrote:
>
> > From: Darren Hart <dvhltc@xxxxxxxxxx>
> >
> > Improve legibility by wrapping finding the top waiter in a function.  This
> > will be used by the follow-on patches for enabling requeue pi.
> > +static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb,
> > +					union futex_key *key)
>
> Can we just have *head as argument instead of *hb ?
>
> > +{
> > +	struct plist_head *head;
> > +	struct futex_q *this;
> > +	struct futex_q *top_waiter = NULL;
>
>   	struct futex_q *this;
>
> > +	head = &hb->chain;
> > +	plist_for_each_entry(this, head, list) {
> > +		if (match_futex(&this->key, key)) {
>   		   	return this;		    
>
> > +			top_waiter = this;
> > +			break;
> > +		}
> > +	}
> > +	return top_waiter;
>
>   	return NULL;
>
> Makes the function half the size.

I'd prefer to keep a futex_hash_bucket in the signature as a plist_head 
doesn't help describe what the function does.  However, I believe I have
addressed your concerns as to length with the following.  Does this look
acceptable?  I'll be resending the entire V6 patch series soon.

/**
 * futex_top_waiter - return the highest priority waiter on a futex
 * @hb:     the hash bucket the futex_q's reside in
 * @key:    the futex key (to distinguish it from other futex futex_q's)
 *
 * Must be called with the hb lock held.
 **/
static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb,
					union futex_key *key)
{
	struct futex_q *this;

	plist_for_each_entry(this, &hb->chain, list) {
		if (match_futex(&this->key, key))
			return this;
	}
	return NULL;
}



--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/