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Commit c2ecba71 authored by Pavel Emelianov's avatar Pavel Emelianov Committed by David S. Miller
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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: default avatarDavid S. Miller <davem@davemloft.net>
parent 5e7d7fa5

include/linux/skbuff.h

+7 −0
Original line number Diff line number Diff line
@@ -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.

 *

net/core/neighbour.c

+4 −1
Original line number Diff line number Diff line
@@ -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;