From c2ecba71717c4f60671175fd26083c35a4b9ad58 Mon Sep 17 00:00:00 2001
From: Pavel Emelianov <xemul@sw.ru>
Date: Tue, 17 Apr 2007 12:45:31 -0700
Subject: [PATCH] [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>
---
include/linux/skbuff.h | 7 +++++++
net/core/neighbour.c | 5 ++++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 0e86b6007a0..5992f65b418 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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.
*
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index cfc60019cf9..841e3f32cab 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -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;
--
2.41.3