Re: [PATCH] list.h: implement list_for_each_entry_safe

[Arnaldo Carvalho de Melo <acme@conectiva.com.br>]

Em Sun, May 04, 2003 at 05:50:32AM -0700, David S. Miller escreveu:
> On Sun, 2003-05-04 at 00:57, Arnaldo Carvalho de Melo wrote:
> > ChangeSet@1.1219, 2003-05-04 04:39:21-03:00, acme@conectiva.com.br
> >   o list.h: implement list_for_each_entry_safe
> 
> Exists already, there is even a _rcu version.

Huh? Where is that? :-)

There is list_for_each_entry and list_for_each_entry_rcu, but not
list_for_each_entry_safe nor, for that matter, list_for_each_entry_safe_rcu.

list_for_each_entry was introduced not so long ago by Rusty, AFAIK, so that we
can simplify traversing lists that before, with just list_for_each & _safe and
_rcu variations required that we use a struct list_head as the loop iteration
variable and have as well another variable of the type contained in the list,
like this:

struct llc_sap *llc_sap_find(u8 sap_value)
{
        struct llc_sap* sap = NULL;
        struct list_head *entry;

        list_for_each(entry, &llc_main_station.sap_list.list) {
                sap = list_entry(entry, struct llc_sap, node);
                if (sap->laddr.lsap == sap_value)
                        goto out;
        }
	sap = NULL;
out:
        return sap;
}

Using the _entry variation this can (and will) be converted to

struct llc_sap *llc_sap_find(u8 sap_value)
{
        struct llc_sap* sap;

        list_for_each_entry(sap, &llc_main_station.sap_list.list, node)
                if (sap->laddr.lsap == sap_value)
                        goto out;
	sap = NULL;
out:
        return sap;
}

But then we need (at least I need for IPX, maybe others) the _entry_safe (and
most likely, at least initially for completeness, the _entry_safe_rcu)
variations. This is what I'm submitting :)

- Arnaldo