Timer handlers do not imply rcu_read_lock(), so my recent fix
triggered a LOCKDEP warning when SYNACK is retransmit.
Lets add rcu_read_lock()/rcu_read_unlock() pairs around ireq->ireq_opt
usages instead of guessing what is done by callers, since it is
not worth the pain.
Get rid of ireq_opt_deref() helper since it hides the logic
without real benefit, since it is now a standard rcu_dereference().
Fixes: 1ad98e9d1bdf ("tcp/dccp: fix lockdep issue when SYN is backlogged")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Reported-by: Willem de Bruijn <will...@google.com>
---
include/net/inet_sock.h | 5 -----
net/dccp/ipv4.c | 4 +++-
net/ipv4/inet_connection_sock.c | 5 ++++-
net/ipv4/tcp_ipv4.c | 4 +++-
4 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index
a8cd5cf9ff5b6ddc50bd2e70d3f9103afa32a3b5..a80fd0ac4563283246f4f53cea1ac0cd17b41dab
100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -130,11 +130,6 @@ static inline int inet_request_bound_dev_if(const struct
sock *sk,
return sk->sk_bound_dev_if;
}
-static inline struct ip_options_rcu *ireq_opt_deref(const struct
inet_request_sock *ireq)
-{
- return rcu_dereference(ireq->ireq_opt);
-}
-
struct inet_cork {
unsigned int flags;
__be32 addr;
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index
b08feb219b44b67eadf408a33649d8c7ec9db2d0..8e08cea6f17866b5fb1619f570de747c6a837cbd
100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -493,9 +493,11 @@ static int dccp_v4_send_response(const struct sock *sk,
struct request_sock *req
dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->ir_loc_addr,
ireq->ir_rmt_addr);
+ rcu_read_lock();
err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
ireq->ir_rmt_addr,
- ireq_opt_deref(ireq));
+ rcu_dereference(ireq->ireq_opt));
+ rcu_read_unlock();
err = net_xmit_eval(err);
}
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index
dfd5009f96ef7111a593651a48f73c4a92c3ed15..15e7f7915a21e0fbce09d5d2c17d877eae499e03
100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -544,7 +544,8 @@ struct dst_entry *inet_csk_route_req(const struct sock *sk,
struct ip_options_rcu *opt;
struct rtable *rt;
- opt = ireq_opt_deref(ireq);
+ rcu_read_lock();
+ opt = rcu_dereference(ireq->ireq_opt);
flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
@@ -558,11 +559,13 @@ struct dst_entry *inet_csk_route_req(const struct sock
*sk,
goto no_route;
if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
goto route_err;
+ rcu_read_unlock();
return &rt->dst;
route_err:
ip_rt_put(rt);
no_route:
+ rcu_read_unlock();
__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
return NULL;
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index
44c09eddbb781c03da2417aaa925e360de01a6e9..cd426313a29819b34648086b551fe9390d8a0b0a
100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -943,9 +943,11 @@ static int tcp_v4_send_synack(const struct sock *sk,
struct dst_entry *dst,
if (skb) {
__tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
+ rcu_read_lock();
err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
ireq->ir_rmt_addr,
- ireq_opt_deref(ireq));
+ rcu_dereference(ireq->ireq_opt));
+ rcu_read_unlock();
err = net_xmit_eval(err);
}
--
2.19.0.605.g01d371f741-goog
