linux-kernel - Re: [PATCH v6 4/8] klist: implement klist

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150728074755.GR21114@x1>
Date:	Tue, 28 Jul 2015 08:47:55 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Vinod Koul <vinod.koul@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	mturquette@...libre.com, sboyd@...eaurora.org
Subject: Re: [PATCH v6 4/8] klist: implement klist_prev()

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 <andriy.shevchenko@...ux.intel.com>
> Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/