diff options
| -rw-r--r-- | fs/seq_file.c | 71 | ||||
| -rw-r--r-- | include/linux/rculist.h | 5 | ||||
| -rw-r--r-- | include/linux/seq_file.h | 15 |
3 files changed, 87 insertions, 4 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c index f65b16f02da3..5afd554efad3 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -750,3 +750,74 @@ struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head, 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(). + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +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. + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +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(). + * + * This list-traversal primitive may safely run concurrently with + * the _rcu list-mutation primitives such as hlist_add_head_rcu() + * as long as the traversal is guarded by rcu_read_lock(). + */ +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); diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 1bf0f708c4fc..701fe9cb552a 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -406,6 +406,11 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev, 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. diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index c95bcdc18f4c..03c0232b4169 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -140,10 +140,17 @@ extern struct list_head *seq_list_next(void *v, struct list_head *head, */ 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 |