Re: [PATCH -mm] [2/3] add list_merge to list.h

[Steven Rostedt]

On Thu, 3 Aug 2006, Andrew Morton wrote:

> On Thu, 3 Aug 2006 19:15:15 -0700
> "Nate Diller" <nate.diller@xxxxxxxxx> wrote:
>
> > +/**
> > + * list_merge - merge two headless lists
> > + * @list: the new list to merge.
> > + * @head: the place to add it in the first list.
> > + *
> > + * This is similar to list_splice(), except it merges every item onto @list,
> > + * not excluding @head itself.  It is a noop if @head already immediately
> > + * preceeds @list.
>
> "precedes"
>
> > + */
> > +static inline void list_merge(struct list_head *list, struct list_head *head)
> > +{
> > +	struct list_head *last = list->prev;
> > +	struct list_head *at = head->next;
> > +
> > +	list->prev = head;
> > +	head->next = list;
> > +
> > +	last->next = at;
> > +	at->prev = last;
> > +}
>
> Interesting.  I didn't realise that none of the existing functions could do
> this.  I wonder if we can flesh the comment out a bit: define "headless" a
> little more verbosely.
>
> Should we call it list_splice_headless() or something?  list_merge is a bit
> vague.
>

Yes, please do explicitly mention headless.  I could see someone using
this for something with a head and causing some strange bugs.

Also, it might be a good idea to get rid of the "head" in the parameter.
Perhaps call it "start" or something else.  It's a little confusing to
have a headless list operation that calls the start of a list "head".

-- Steve

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