From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH][NETNS] Use list_for_each_entry_continue_reverse in setup_net Date: Mon, 17 Sep 2007 07:07:42 -0600 Message-ID: References: <46EE5EDD.1030005@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , Linux Netdev List , devel@openvz.org To: Pavel Emelyanov Return-path: Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:55323 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753511AbXIQNHy (ORCPT ); Mon, 17 Sep 2007 09:07:54 -0400 In-Reply-To: <46EE5EDD.1030005@openvz.org> (Pavel Emelyanov's message of "Mon, 17 Sep 2007 15:02:53 +0400") Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Pavel Emelyanov writes: > I proposed introducing a list_for_each_entry_continue_reverse > macro to be used in setup_net() when unrolling the failed > ->init callback. > > Here is the macro and some more cleanup in the setup_net() itself > to remove one variable from the stack :) Minor, but the code > looks nicer. > > Signed-off-by: Pavel Emelyanov > Acked-by: "Eric W. Biederman" Pavel if you are going down this route. Could you look at cleanup_net as well. The reverse walk there could probably benefit from being list_for_each_entry_reverse. Eric > > --- > > include/linux/list.h | 14 ++++++++++++++ > net/core/net_namespace.c | 8 +++----- > 2 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/include/linux/list.h b/include/linux/list.h > index f29fc9c..ad9dcb9 100644 > --- a/include/linux/list.h > +++ b/include/linux/list.h > @@ -525,6 +525,20 @@ static inline void list_splice_init_rcu( > pos = list_entry(pos->member.next, typeof(*pos), member)) > > /** > + * list_for_each_entry_continue_reverse - iterate backwards from the given > point > + * @pos: the type * to use as a loop cursor. > + * @head: the head for your list. > + * @member: the name of the list_struct within the struct. > + * > + * Start to iterate over list of given type backwards, continuing after > + * the current position. > + */ > +#define list_for_each_entry_continue_reverse(pos, head, member) \ > + for (pos = list_entry(pos->member.prev, typeof(*pos), member); \ > + prefetch(pos->member.prev), &pos->member != (head); \ > + pos = list_entry(pos->member.prev, typeof(*pos), member)) > + > +/** > * list_for_each_entry_from - iterate over list of given type from the current > point > * @pos: the type * to use as a loop cursor. > * @head: the head for your list. > diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c > index 1fc513c..a9dd261 100644 > --- a/net/core/net_namespace.c > +++ b/net/core/net_namespace.c > @@ -102,7 +102,6 @@ static int setup_net(struct net *net) > { > /* Must be called with net_mutex held */ > struct pernet_operations *ops; > - struct list_head *ptr; > int error; > > memset(net, 0, sizeof(struct net)); > @@ -110,8 +109,7 @@ static int setup_net(struct net *net) > atomic_set(&net->use_count, 0); > > error = 0; > - list_for_each(ptr, &pernet_list) { > - ops = list_entry(ptr, struct pernet_operations, list); > + list_for_each_entry(ops, &pernet_list, list) { > if (ops->init) { > error = ops->init(net); > if (error < 0) > @@ -120,12 +118,12 @@ static int setup_net(struct net *net) > } > out: > return error; > + > out_undo: > /* Walk through the list backwards calling the exit functions > * for the pernet modules whose init functions did not fail. > */ > - for (ptr = ptr->prev; ptr != &pernet_list; ptr = ptr->prev) { > - ops = list_entry(ptr, struct pernet_operations, list); > + list_for_each_entry_continue_reverse(ops, &pernet_list, list) { > if (ops->exit) > ops->exit(net); > }