From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755446AbbG1HsE (ORCPT ); Tue, 28 Jul 2015 03:48:04 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:35192 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755416AbbG1HsA (ORCPT ); Tue, 28 Jul 2015 03:48:00 -0400 Date: Tue, 28 Jul 2015 08:47:55 +0100 From: Lee Jones To: Andy Shevchenko Cc: linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, Greg Kroah-Hartman , Vinod Koul , Mika Westerberg , linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Heikki Krogerus , Jarkko Nikula , "Wysocki, Rafael J" , mturquette@baylibre.com, sboyd@codeaurora.org Subject: Re: [PATCH v6 4/8] klist: implement klist_prev() Message-ID: <20150728074755.GR21114@x1> References: <1438009443-55317-1-git-send-email-andriy.shevchenko@linux.intel.com> <1438009443-55317-5-git-send-email-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1438009443-55317-5-git-send-email-andriy.shevchenko@linux.intel.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 Mon, 27 Jul 2015, Andy Shevchenko wrote: > klist_prev() gets the previous element in the list. It is useful to traverse > through the list in reverse order, for example, to provide LIFO (last in first > out) variant of access. > > Signed-off-by: Andy Shevchenko > Acked-by: Greg Kroah-Hartman > --- > include/linux/klist.h | 1 + > lib/klist.c | 41 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 42 insertions(+) Applied, thanks. Pull request to follow. > diff --git a/include/linux/klist.h b/include/linux/klist.h > index 61e5b72..953f283 100644 > --- a/include/linux/klist.h > +++ b/include/linux/klist.h > @@ -63,6 +63,7 @@ extern void klist_iter_init(struct klist *k, struct klist_iter *i); > extern void klist_iter_init_node(struct klist *k, struct klist_iter *i, > struct klist_node *n); > extern void klist_iter_exit(struct klist_iter *i); > +extern struct klist_node *klist_prev(struct klist_iter *i); > extern struct klist_node *klist_next(struct klist_iter *i); > > #endif > diff --git a/lib/klist.c b/lib/klist.c > index 89b485a..d74cf7a 100644 > --- a/lib/klist.c > +++ b/lib/klist.c > @@ -324,6 +324,47 @@ static struct klist_node *to_klist_node(struct list_head *n) > } > > /** > + * klist_prev - Ante up prev node in list. > + * @i: Iterator structure. > + * > + * First grab list lock. Decrement the reference count of the previous > + * node, if there was one. Grab the prev node, increment its reference > + * count, drop the lock, and return that prev node. > + */ > +struct klist_node *klist_prev(struct klist_iter *i) > +{ > + void (*put)(struct klist_node *) = i->i_klist->put; > + struct klist_node *last = i->i_cur; > + struct klist_node *prev; > + > + spin_lock(&i->i_klist->k_lock); > + > + if (last) { > + prev = to_klist_node(last->n_node.prev); > + if (!klist_dec_and_del(last)) > + put = NULL; > + } else > + prev = to_klist_node(i->i_klist->k_list.prev); > + > + i->i_cur = NULL; > + while (prev != to_klist_node(&i->i_klist->k_list)) { > + if (likely(!knode_dead(prev))) { > + kref_get(&prev->n_ref); > + i->i_cur = prev; > + break; > + } > + prev = to_klist_node(prev->n_node.prev); > + } > + > + spin_unlock(&i->i_klist->k_lock); > + > + if (put && last) > + put(last); > + return i->i_cur; > +} > +EXPORT_SYMBOL_GPL(klist_prev); > + > +/** > * klist_next - Ante up next node in list. > * @i: Iterator structure. > * -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog