Browse Source

seq_file: add RCU versions of new hlist/list iterators (v3)

Many usages of seq_file use RCU protected lists, so non RCU
iterators will not work safely.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
master
stephen hemminger 12 years ago
committed by David S. Miller
parent
commit
1cc523271e
  1. 71
      fs/seq_file.c
  2. 5
      include/linux/rculist.h
  3. 15
      include/linux/seq_file.h

71
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);

5
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.

15
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

Loading…
Cancel
Save