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Subject[tip:core/rcu] net: Add checking to rcu_dereference() primitives
Commit-ID:  a898def29e4119bc01ebe7ca97423181f4c0ea2d
Gitweb: http://git.kernel.org/tip/a898def29e4119bc01ebe7ca97423181f4c0ea2d
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
AuthorDate: Mon, 22 Feb 2010 17:04:49 -0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 25 Feb 2010 09:41:03 +0100

net: Add checking to rcu_dereference() primitives

Update rcu_dereference() primitives to use new lockdep-based
checking. The rcu_dereference() in __in6_dev_get() may be
protected either by rcu_read_lock() or RTNL, per Eric Dumazet.
The rcu_dereference() in __sk_free() is protected by the fact
that it is never reached if an update could change it. Check
for this by using rcu_dereference_check() to verify that the
struct sock's ->sk_wmem_alloc counter is zero.

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-5-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/rtnetlink.h | 3 +++
include/net/addrconf.h | 4 +++-
net/core/dev.c | 2 +-
net/core/filter.c | 6 +++---
net/core/rtnetlink.c | 8 ++++++++
net/core/sock.c | 3 ++-
net/decnet/dn_route.c | 14 +++++++-------
net/ipv4/route.c | 14 +++++++-------
net/packet/af_packet.c | 2 +-
9 files changed, 35 insertions(+), 21 deletions(-)
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 05330fc..5c52fa4 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -735,6 +735,9 @@ extern void rtnl_lock(void);
extern void rtnl_unlock(void);
extern int rtnl_trylock(void);
extern int rtnl_is_locked(void);
+#ifdef CONFIG_PROVE_LOCKING
+extern int lockdep_rtnl_is_held(void);
+#endif /* #ifdef CONFIG_PROVE_LOCKING */

extern void rtnetlink_init(void);
extern void __rtnl_unlock(void);
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 0f7c378..45375b4 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -177,7 +177,9 @@ extern int unregister_inet6addr_notifier(struct notifier_block *nb);
static inline struct inet6_dev *
__in6_dev_get(struct net_device *dev)
{
- return rcu_dereference(dev->ip6_ptr);
+ return rcu_dereference_check(dev->ip6_ptr,
+ rcu_read_lock_held() ||
+ lockdep_rtnl_is_held());
}

static inline struct inet6_dev *
diff --git a/net/core/dev.c b/net/core/dev.c
index ec87421..bb1f1da 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2041,7 +2041,7 @@ gso:
rcu_read_lock_bh();

txq = dev_pick_tx(dev, skb);
- q = rcu_dereference(txq->qdisc);
+ q = rcu_dereference_bh(txq->qdisc);

#ifdef CONFIG_NET_CLS_ACT
skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_EGRESS);
diff --git a/net/core/filter.c b/net/core/filter.c
index 08db7b9..3541aa4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -86,7 +86,7 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
return err;

rcu_read_lock_bh();
- filter = rcu_dereference(sk->sk_filter);
+ filter = rcu_dereference_bh(sk->sk_filter);
if (filter) {
unsigned int pkt_len = sk_run_filter(skb, filter->insns,
filter->len);
@@ -521,7 +521,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
}

rcu_read_lock_bh();
- old_fp = rcu_dereference(sk->sk_filter);
+ old_fp = rcu_dereference_bh(sk->sk_filter);
rcu_assign_pointer(sk->sk_filter, fp);
rcu_read_unlock_bh();

@@ -536,7 +536,7 @@ int sk_detach_filter(struct sock *sk)
struct sk_filter *filter;

rcu_read_lock_bh();
- filter = rcu_dereference(sk->sk_filter);
+ filter = rcu_dereference_bh(sk->sk_filter);
if (filter) {
rcu_assign_pointer(sk->sk_filter, NULL);
sk_filter_delayed_uncharge(sk, filter);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 794bcb8..4c7d3f6 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -89,6 +89,14 @@ int rtnl_is_locked(void)
}
EXPORT_SYMBOL(rtnl_is_locked);

+#ifdef CONFIG_PROVE_LOCKING
+int lockdep_rtnl_is_held(void)
+{
+ return lockdep_is_held(&rtnl_mutex);
+}
+EXPORT_SYMBOL(lockdep_rtnl_is_held);
+#endif /* #ifdef CONFIG_PROVE_LOCKING */
+
static struct rtnl_link *rtnl_msg_handlers[NPROTO];

static inline int rtm_msgindex(int msgtype)
diff --git a/net/core/sock.c b/net/core/sock.c
index e1f6f22..305cba4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1073,7 +1073,8 @@ static void __sk_free(struct sock *sk)
if (sk->sk_destruct)
sk->sk_destruct(sk);

- filter = rcu_dereference(sk->sk_filter);
+ filter = rcu_dereference_check(sk->sk_filter,
+ atomic_read(&sk->sk_wmem_alloc) == 0);
if (filter) {
sk_filter_uncharge(sk, filter);
rcu_assign_pointer(sk->sk_filter, NULL);
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index a032840..a7bf03c 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1155,8 +1155,8 @@ static int __dn_route_output_key(struct dst_entry **pprt, const struct flowi *fl

if (!(flags & MSG_TRYHARD)) {
rcu_read_lock_bh();
- for(rt = rcu_dereference(dn_rt_hash_table[hash].chain); rt;
- rt = rcu_dereference(rt->u.dst.dn_next)) {
+ for (rt = rcu_dereference_bh(dn_rt_hash_table[hash].chain); rt;
+ rt = rcu_dereference_bh(rt->u.dst.dn_next)) {
if ((flp->fld_dst == rt->fl.fld_dst) &&
(flp->fld_src == rt->fl.fld_src) &&
(flp->mark == rt->fl.mark) &&
@@ -1618,9 +1618,9 @@ int dn_cache_dump(struct sk_buff *skb, struct netlink_callback *cb)
if (h > s_h)
s_idx = 0;
rcu_read_lock_bh();
- for(rt = rcu_dereference(dn_rt_hash_table[h].chain), idx = 0;
+ for(rt = rcu_dereference_bh(dn_rt_hash_table[h].chain), idx = 0;
rt;
- rt = rcu_dereference(rt->u.dst.dn_next), idx++) {
+ rt = rcu_dereference_bh(rt->u.dst.dn_next), idx++) {
if (idx < s_idx)
continue;
skb_dst_set(skb, dst_clone(&rt->u.dst));
@@ -1654,12 +1654,12 @@ static struct dn_route *dn_rt_cache_get_first(struct seq_file *seq)

for(s->bucket = dn_rt_hash_mask; s->bucket >= 0; --s->bucket) {
rcu_read_lock_bh();
- rt = dn_rt_hash_table[s->bucket].chain;
+ rt = rcu_dereference_bh(dn_rt_hash_table[s->bucket].chain);
if (rt)
break;
rcu_read_unlock_bh();
}
- return rcu_dereference(rt);
+ return rt;
}

static struct dn_route *dn_rt_cache_get_next(struct seq_file *seq, struct dn_route *rt)
@@ -1674,7 +1674,7 @@ static struct dn_route *dn_rt_cache_get_next(struct seq_file *seq, struct dn_rou
rcu_read_lock_bh();
rt = dn_rt_hash_table[s->bucket].chain;
}
- return rcu_dereference(rt);
+ return rcu_dereference_bh(rt);
}

static void *dn_rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d62b05d..4f11faa 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -287,12 +287,12 @@ static struct rtable *rt_cache_get_first(struct seq_file *seq)
if (!rt_hash_table[st->bucket].chain)
continue;
rcu_read_lock_bh();
- r = rcu_dereference(rt_hash_table[st->bucket].chain);
+ r = rcu_dereference_bh(rt_hash_table[st->bucket].chain);
while (r) {
if (dev_net(r->u.dst.dev) == seq_file_net(seq) &&
r->rt_genid == st->genid)
return r;
- r = rcu_dereference(r->u.dst.rt_next);
+ r = rcu_dereference_bh(r->u.dst.rt_next);
}
rcu_read_unlock_bh();
}
@@ -314,7 +314,7 @@ static struct rtable *__rt_cache_get_next(struct seq_file *seq,
rcu_read_lock_bh();
r = rt_hash_table[st->bucket].chain;
}
- return rcu_dereference(r);
+ return rcu_dereference_bh(r);
}

static struct rtable *rt_cache_get_next(struct seq_file *seq,
@@ -2689,8 +2689,8 @@ int __ip_route_output_key(struct net *net, struct rtable **rp,
hash = rt_hash(flp->fl4_dst, flp->fl4_src, flp->oif, rt_genid(net));

rcu_read_lock_bh();
- for (rth = rcu_dereference(rt_hash_table[hash].chain); rth;
- rth = rcu_dereference(rth->u.dst.rt_next)) {
+ for (rth = rcu_dereference_bh(rt_hash_table[hash].chain); rth;
+ rth = rcu_dereference_bh(rth->u.dst.rt_next)) {
if (rth->fl.fl4_dst == flp->fl4_dst &&
rth->fl.fl4_src == flp->fl4_src &&
rth->fl.iif == 0 &&
@@ -3008,8 +3008,8 @@ int ip_rt_dump(struct sk_buff *skb, struct netlink_callback *cb)
if (!rt_hash_table[h].chain)
continue;
rcu_read_lock_bh();
- for (rt = rcu_dereference(rt_hash_table[h].chain), idx = 0; rt;
- rt = rcu_dereference(rt->u.dst.rt_next), idx++) {
+ for (rt = rcu_dereference_bh(rt_hash_table[h].chain), idx = 0; rt;
+ rt = rcu_dereference_bh(rt->u.dst.rt_next), idx++) {
if (!net_eq(dev_net(rt->u.dst.dev), net) || idx < s_idx)
continue;
if (rt_is_expired(rt))
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index f126d18..939471e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -508,7 +508,7 @@ static inline unsigned int run_filter(struct sk_buff *skb, struct sock *sk,
struct sk_filter *filter;

rcu_read_lock_bh();
- filter = rcu_dereference(sk->sk_filter);
+ filter = rcu_dereference_bh(sk->sk_filter);
if (filter != NULL)
res = sk_run_filter(skb, filter->insns, filter->len);
rcu_read_unlock_bh();

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