Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754019AbZDNPe3 (ORCPT ); Tue, 14 Apr 2009 11:34:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752240AbZDNPeU (ORCPT ); Tue, 14 Apr 2009 11:34:20 -0400 Received: from mx2.redhat.com ([66.187.237.31]:41566 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752087AbZDNPeU (ORCPT ); Tue, 14 Apr 2009 11:34:20 -0400 Date: Tue, 14 Apr 2009 17:33:57 +0200 From: Jiri Pirko To: linux-kernel@vger.kernel.org Cc: dipankar@in.ibm.com, paulmck@linux.vnet.ibm.com, mingo@elte.hu Subject: [PATCH] rculist.h: introduce list_entry_rcu and list_first_entry_rcu Message-ID: <20090414153356.GC3999@psychotron.englab.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2619 Lines: 68 I've run into the situation where I need to use list_first_entry with rcu-guarded list. This patch introduces this. Also changed list_for_each_entry_rcu to use new list_entry_rcu instead of list_entry. Jirka Signed-off-by: Jiri Pirko --- include/linux/rculist.h | 30 ++++++++++++++++++++++++++++-- 1 files changed, 28 insertions(+), 2 deletions(-) diff --git a/include/linux/rculist.h b/include/linux/rculist.h index e649bd3..5710f43 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -198,6 +198,32 @@ static inline void list_splice_init_rcu(struct list_head *list, at->prev = last; } +/** + * list_entry_rcu - get the struct for this entry + * @ptr: the &struct list_head pointer. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct within the struct. + * + * This primitive may safely run concurrently with the _rcu list-mutation + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). + */ +#define list_entry_rcu(ptr, type, member) \ + container_of(rcu_dereference(ptr), type, member) + +/** + * list_first_entry_rcu - get the first element from a list + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct within the struct. + * + * Note, that list is expected to be not empty. + * + * This primitive may safely run concurrently with the _rcu list-mutation + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). + */ +#define list_first_entry_rcu(ptr, type, member) \ + list_entry_rcu((ptr)->next, type, member) + #define __list_for_each_rcu(pos, head) \ for (pos = rcu_dereference((head)->next); \ pos != (head); \ @@ -214,9 +240,9 @@ static inline void list_splice_init_rcu(struct list_head *list, * as long as the traversal is guarded by rcu_read_lock(). */ #define list_for_each_entry_rcu(pos, head, member) \ - for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \ + for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ prefetch(pos->member.next), &pos->member != (head); \ - pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member)) + pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) /** -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/