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authorEric Dumazet <edumazet@google.com>2012-06-05 03:00:18 +0000
committerDavid S. Miller <davem@davemloft.net>2012-06-06 10:45:15 -0700
commit55432d2b543a4b6dfae54f5c432a566877a85d90 (patch)
treef830eb5150e38be149fcfce74f68716f5bf2641a
parentnet: sierra_net: device IDs for Aircard 320U++ (diff)
downloadlinux-dev-55432d2b543a4b6dfae54f5c432a566877a85d90.tar.xz
linux-dev-55432d2b543a4b6dfae54f5c432a566877a85d90.zip
inetpeer: fix a race in inetpeer_gc_worker()
commit 5faa5df1fa2024 (inetpeer: Invalidate the inetpeer tree along with the routing cache) added a race : Before freeing an inetpeer, we must respect a RCU grace period, and make sure no user will attempt to increase refcnt. inetpeer_invalidate_tree() waits for a RCU grace period before inserting inetpeer tree into gc_list and waking the worker. At that time, no concurrent lookup can find a inetpeer in this tree. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/inetpeer.h5
-rw-r--r--net/ipv4/inetpeer.c16
2 files changed, 16 insertions, 5 deletions
diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
index b94765e38e80..2040bff945d4 100644
--- a/include/net/inetpeer.h
+++ b/include/net/inetpeer.h
@@ -40,7 +40,10 @@ struct inet_peer {
u32 pmtu_orig;
u32 pmtu_learned;
struct inetpeer_addr_base redirect_learned;
- struct list_head gc_list;
+ union {
+ struct list_head gc_list;
+ struct rcu_head gc_rcu;
+ };
/*
* Once inet_peer is queued for deletion (refcnt == -1), following fields
* are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index d4d61b694fab..dfba343b2509 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -560,6 +560,17 @@ bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
}
EXPORT_SYMBOL(inet_peer_xrlim_allow);
+static void inetpeer_inval_rcu(struct rcu_head *head)
+{
+ struct inet_peer *p = container_of(head, struct inet_peer, gc_rcu);
+
+ spin_lock_bh(&gc_lock);
+ list_add_tail(&p->gc_list, &gc_list);
+ spin_unlock_bh(&gc_lock);
+
+ schedule_delayed_work(&gc_work, gc_delay);
+}
+
void inetpeer_invalidate_tree(int family)
{
struct inet_peer *old, *new, *prev;
@@ -576,10 +587,7 @@ void inetpeer_invalidate_tree(int family)
prev = cmpxchg(&base->root, old, new);
if (prev == old) {
base->total = 0;
- spin_lock(&gc_lock);
- list_add_tail(&prev->gc_list, &gc_list);
- spin_unlock(&gc_lock);
- schedule_delayed_work(&gc_work, gc_delay);
+ call_rcu(&prev->gc_rcu, inetpeer_inval_rcu);
}
out: