From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754885AbdERCD6 (ORCPT ); Wed, 17 May 2017 22:03:58 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:36742 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754109AbdERCDy (ORCPT ); Wed, 17 May 2017 22:03:54 -0400 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Thu, 18 May 2017 11:03:44 +0900 From: Byungchul Park To: peterz@infradead.org Cc: linux-kernel@vger.kernel.org, kernel-team@lge.com, ying.huang@intel.com Subject: Re: [RESEND PATCH] llist: Provide a safe version for llist_for_each Message-ID: <20170518020344.GE28017@X58A-UD3R> References: <1494549416-10539-1-git-send-email-byungchul.park@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1494549416-10539-1-git-send-email-byungchul.park@lge.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 12, 2017 at 09:36:56AM +0900, Byungchul Park wrote: > Sometimes we have to dereference next field of llist node before entering > loop becasue the node might be deleted or the next field might be > modified within the loop. So this adds the safe version of llist_for_each, > that is, llist_for_each_safe. +cc ying.huang@intel.com > > Signed-off-by: Byungchul Park > Reviewed-by: "Huang, Ying" > --- > include/linux/llist.h | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/include/linux/llist.h b/include/linux/llist.h > index fd4ca0b..b90c9f2 100644 > --- a/include/linux/llist.h > +++ b/include/linux/llist.h > @@ -105,6 +105,25 @@ static inline void init_llist_head(struct llist_head *list) > for ((pos) = (node); pos; (pos) = (pos)->next) > > /** > + * llist_for_each_safe - iterate over some deleted entries of a lock-less list > + * safe against removal of list entry > + * @pos: the &struct llist_node to use as a loop cursor > + * @n: another &struct llist_node to use as temporary storage > + * @node: the first entry of deleted list entries > + * > + * In general, some entries of the lock-less list can be traversed > + * safely only after being deleted from list, so start with an entry > + * instead of list head. > + * > + * If being used on entries deleted from lock-less list directly, the > + * traverse order is from the newest to the oldest added entry. If > + * you want to traverse from the oldest to the newest, you must > + * reverse the order by yourself before traversing. > + */ > +#define llist_for_each_safe(pos, n, node) \ > + for ((pos) = (node); (pos) && ((n) = (pos)->next, true); (pos) = (n)) > + > +/** > * llist_for_each_entry - iterate over some deleted entries of lock-less list of given type > * @pos: the type * to use as a loop cursor. > * @node: the fist entry of deleted list entries. > -- > 1.9.1