[PATCH] list.h: implement list_for_each_entry_safe

[PATCH] list.h: implement list_for_each_entry_safe

[Arnaldo Carvalho de Melo]

Hi Linus,

	Please consider pulling from:

bk://kernel.bkbits.net/acme/list-2.5

	I started converting IPX to struct list_head and also to use
list_for_eache_entry to simplify the code in the network families I maintain,
and in IPX I need the _safe variation for list_for_eache_entry.

- Arnaldo

You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.

===================================================================


ChangeSet@1.1219, 2003-05-04 04:39:21-03:00, acme@conectiva.com.br
  o list.h: implement list_for_each_entry_safe


 list.h |   13 +++++++++++++
 1 files changed, 13 insertions(+)


diff -Nru a/include/linux/list.h b/include/linux/list.h
--- a/include/linux/list.h	Sun May  4 04:43:59 2003
+++ b/include/linux/list.h	Sun May  4 04:43:59 2003
@@ -297,6 +297,19 @@
 		     prefetch(pos->member.next))
 
 /**
+ * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @pos:	the type * to use as a loop counter.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member)			\
+	for (pos = list_entry((head)->next, typeof(*pos), member),	\
+		n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head); 					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
  * list_for_each_rcu	-	iterate over an rcu-protected list
  * @pos:	the &struct list_head to use as a loop counter.
  * @head:	the head for your list.

===================================================================


This BitKeeper patch contains the following changesets:
1.1219
## Wrapped with gzip_uu ##


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Re: [PATCH] list.h: implement list_for_each_entry_safe

[David S. Miller]

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.

-- 
David S. Miller <davem@redhat.com>

Re: [PATCH] list.h: implement list_for_each_entry_safe

[David S. Miller]

   From: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   Date: Sun, 4 May 2003 18:24:38 -0300

   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? :-)
   
I misread your email, sorry.  Your patch is ok.

Re: [PATCH] list.h: implement list_for_each_entry_safe

[Arnaldo Carvalho de Melo]

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