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[NET]: Set a separate lockdep class for neighbour table's proxy_queue 

Otherwise the following calltrace will lead to a wrong
lockdep warning:

  neigh_proxy_process()
    `- lock(neigh_table->proxy_queue.lock);
  arp_redo /* via tbl->proxy_redo */
  arp_process
  neigh_event_ns
  neigh_update
  skb_queue_purge
    `- lock(neighbor->arp_queue.lock);

This is not a deadlock actually, as neighbor table's proxy_queue
and the neighbor's arp_queue are different queues.

Lockdep thinks there is a deadlock as both queues are initialized
with skb_queue_head_init() and thus have a common class.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelianov 2007-04-17 12:45:31 -07:00 committed by David S. Miller
parent 5e7d7fa573
commit c2ecba7171
2 changed files with 11 additions and 1 deletions
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7
include/linux/skbuff.h
View File

@ -619,6 +619,13 @@ static inline void skb_queue_head_init(struct sk_buff_head *list)
list->qlen = 0;
}
static inline void skb_queue_head_init_class(struct sk_buff_head *list,
struct lock_class_key *class)
{
skb_queue_head_init(list);
lockdep_set_class(&list->lock, class);
}
/*
* Insert an sk_buff at the start of a list.
*

5
net/core/neighbour.c
View File

@ -1331,6 +1331,8 @@ void neigh_parms_destroy(struct neigh_parms *parms)
kfree(parms);
}
static struct lock_class_key neigh_table_proxy_queue_class;
void neigh_table_init_no_netlink(struct neigh_table *tbl)
{
unsigned long now = jiffies;
@ -1379,7 +1381,8 @@ void neigh_table_init_no_netlink(struct neigh_table *tbl)
init_timer(&tbl->proxy_timer);
tbl->proxy_timer.data = (unsigned long)tbl;
tbl->proxy_timer.function = neigh_proxy_process;
skb_queue_head_init(&tbl->proxy_queue);
skb_queue_head_init_class(&tbl->proxy_queue,
&neigh_table_proxy_queue_class);
tbl->last_flush = now;
tbl->last_rand = now + tbl->parms.reachable_time * 20;