Many usages of seq_file use RCU protected lists, so non RCU iterators will not work safely. Needed to make __hlist_for_each_rcu macro (like __list_for_each_rcu). Also indented prototypes to match existing style. Signed-off-by: Stephen Hemminger --- fs/seq_file.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/rculist.h | 5 ++ include/linux/seq_file.h | 27 +++++++++----- 3 files changed, 111 insertions(+), 9 deletions(-) --- a/fs/seq_file.c 2010-02-18 15:08:53.228872265 -0800 +++ b/fs/seq_file.c 2010-02-18 15:37:09.660996801 -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 +782,59 @@ 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_head_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) +{ + struct hlist_node *node = v; + + ++*ppos; + if (v == SEQ_START_TOKEN) + return rcu_dereference(head->first); + else + return rcu_dereference(node->next); +} +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 15:33:26.352872829 -0800 @@ -406,6 +406,11 @@ static inline void hlist_add_after_rcu(s n->next->pprev = &n->next; } +#define __hlist_for_each_rcu(pos, head) \ + for (pos = rcu_dereference((head)->first); \ + pos && ({ prefetch(pos->next); 1; }); \ + pos = rcu_dereference(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/