Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752450Ab0BRXa6 (ORCPT ); Thu, 18 Feb 2010 18:30:58 -0500 Received: from mail.vyatta.com ([76.74.103.46]:59359 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752114Ab0BRXa5 (ORCPT ); Thu, 18 Feb 2010 18:30:57 -0500 Date: Thu, 18 Feb 2010 15:30:41 -0800 From: Stephen Hemminger To: "David S. Miller" , "Paul E. McKenney" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] seq_file: add RCU versions of new hlist/list iterators Message-ID: <20100218153041.2f722db8@nehalam> Organization: Vyatta X-Mailer: Claws Mail 3.7.2 (GTK+ 2.18.3; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5202 Lines: 169 Many usages of seq_file use RCU protected lists, so non RCU iterators will not work safely. Signed-off-by: Stephen Hemminger --- fs/seq_file.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/rculist.h | 5 ++ include/linux/seq_file.h | 27 ++++++++++----- 3 files changed, 105 insertions(+), 9 deletions(-) --- a/fs/seq_file.c 2010-02-18 15:08:53.228872265 -0800 +++ b/fs/seq_file.c 2010-02-18 15:26:21.157402219 -0800 @@ -695,6 +695,38 @@ struct list_head *seq_list_next(void *v, } EXPORT_SYMBOL(seq_list_next); +struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos) +{ + struct list_head *lh; + + __list_for_each_rcu(lh, head) + if (pos-- == 0) + return lh; + + return NULL; +} +EXPORT_SYMBOL(seq_list_start_rcu); + +struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos) +{ + if (!pos) + return head; + + return seq_list_start_rcu(head, pos - 1); +} +EXPORT_SYMBOL(seq_list_start_head_rcu); + +struct list_head *seq_list_next_rcu(void *v, struct list_head *head, + loff_t *ppos) +{ + struct list_head *lh = v; + + lh = rcu_dereference(lh->next); + ++*ppos; + return lh == head ? NULL : lh; +} +EXPORT_SYMBOL(seq_list_next_rcu); + /** * seq_hlist_start - start an iteration of a hlist * @head: the head of the hlist @@ -750,3 +782,53 @@ struct hlist_node *seq_hlist_next(void * return node->next; } EXPORT_SYMBOL(seq_hlist_next); + +/** + * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). + */ +struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head, loff_t pos) +{ + struct hlist_node *node; + + __hlist_for_each_rcu(node, head) + if (pos-- == 0) + return node; + return NULL; +} +EXPORT_SYMBOL(seq_hlist_start_rcu); + +/** + * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU + * @head: the head of the hlist + * @pos: the start position of the sequence + * + * Called at seq_file->op->start(). Call this function if you want to + * print a header at the top of the output. + */ +struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head, loff_t pos) +{ + if (!pos) + return SEQ_START_TOKEN; + + return seq_hlist_start_rcu(head, pos - 1); +} +EXPORT_SYMBOL(seq_hlist_start_rcu); + +/** + * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU + * @v: the current iterator + * @head: the head of the hlist + * @pos: the current posision + * + * Called at seq_file->op->next(). + */ +struct hlist_node *seq_hlist_next_rcu(void *v, struct hlist_head *head, + loff_t *ppos) +{ + return rcu_dereference(seq_hlist_next(v, head, ppos)); +} +EXPORT_SYMBOL(seq_hlist_next_rcu); --- a/include/linux/seq_file.h 2010-02-18 15:08:53.256872028 -0800 +++ b/include/linux/seq_file.h 2010-02-18 15:09:14.128997914 -0800 @@ -127,23 +127,32 @@ int seq_release_private(struct inode *, /* * Helpers for iteration over list_head-s in seq_files */ - extern struct list_head *seq_list_start(struct list_head *head, - loff_t pos); + loff_t pos); extern struct list_head *seq_list_start_head(struct list_head *head, - loff_t pos); + loff_t pos); extern struct list_head *seq_list_next(void *v, struct list_head *head, - loff_t *ppos); - + loff_t *ppos); +extern struct list_head *seq_list_start_rcu(struct list_head *head, + loff_t pos); +extern struct list_head *seq_list_start_head_rcu(struct list_head *head, + loff_t pos); +extern struct list_head *seq_list_next_rcu(void *v, struct list_head *head, + loff_t *ppos); /* * Helpers for iteration over hlist_head-s in seq_files */ - extern struct hlist_node *seq_hlist_start(struct hlist_head *head, - loff_t pos); + loff_t pos); extern struct hlist_node *seq_hlist_start_head(struct hlist_head *head, - loff_t pos); + loff_t pos); extern struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head, - loff_t *ppos); + loff_t *ppos); +extern struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head, + loff_t pos); +extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head, + loff_t pos); +extern struct hlist_node *seq_hlist_next_rcu(void *v, struct hlist_head *head, + loff_t *ppos); #endif --- a/include/linux/rculist.h 2010-02-18 15:25:03.681496691 -0800 +++ b/include/linux/rculist.h 2010-02-18 15:26:13.909286656 -0800 @@ -406,6 +406,11 @@ static inline void hlist_add_after_rcu(s n->next->pprev = &n->next; } +#define __hlist_for_each(pos, head) \ + for (pos = rcu_dereference((head)->first); \ + pos && ({ prefetch(pos->next); 1; }); \ + pos = rcu_derference(pos->next)) + /** * hlist_for_each_entry_rcu - iterate over rcu list of given type * @tpos: the type * to use as a loop cursor. -- 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/