[PATCH v6.1.y 3/4] net: dst: introduce dst->dev_rcu
"Miguel Gazquez (Schneider Electric)" <[email protected]>
| Newsgroups | gmane.comp.security.firewalls.netfilter.devel,gmane.linux.kernel.stable,gmane.linux.network,gmane.linux.kernel |
|---|---|
| Message-ID | <[email protected]> |
From: Eric Dumazet <[email protected]> [ Upstream commit caedcc5b6df1b2e2b5f39079e3369c1d4d5c5f50 ] Followup of commit 88fe14253e18 ("net: dst: add four helpers to annotate data-races around dst->dev"). We want to gradually add explicit RCU protection to dst->dev, including lockdep support. Add an union to alias dst->dev_rcu and dst->dev. Add dst_dev_net_rcu() helper. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet <[email protected]> Reviewed-by: David Ahern <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]> Signed-off-by: Miguel Gazquez <[email protected]> --- include/net/dst.h | 16 +++++++++++----- net/core/dst.c | 2 +- net/ipv4/route.c | 4 ++-- 3 files changed, 14 insertions(+), 8 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index 7c0cf856154d..96dd65a941c5 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -23,7 +23,10 @@ struct sk_buff; struct dst_entry { - struct net_device *dev; + union { + struct net_device *dev; + struct net_device __rcu *dev_rcu; + }; struct dst_ops *ops; unsigned long _metrics; unsigned long expires; @@ -562,9 +565,12 @@ static inline struct net_device *dst_dev(const struct dst_entry *dst) static inline struct net_device *dst_dev_rcu(const struct dst_entry *dst) { - /* In the future, use rcu_dereference(dst->dev) */ - WARN_ON_ONCE(!rcu_read_lock_held()); - return READ_ONCE(dst->dev); + return rcu_dereference(dst->dev_rcu); +} + +static inline struct net *dst_dev_net_rcu(const struct dst_entry *dst) +{ + return dev_net_rcu(dst_dev_rcu(dst)); } static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) @@ -584,7 +590,7 @@ static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) { - return dev_net_rcu(skb_dst_dev(skb)); + return dev_net_rcu(skb_dst_dev_rcu(skb)); } struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie); diff --git a/net/core/dst.c b/net/core/dst.c index 24a1cc3d2a08..cbb6888aa32b 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -151,7 +151,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev, true); dst->input = dst_discard; dst->output = dst_discard_out; - WRITE_ONCE(dst->dev, blackhole_netdev); + rcu_assign_pointer(dst->dev_rcu, blackhole_netdev); netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker, GFP_ATOMIC); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index a2985265c792..e3cce307e0e9 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1069,7 +1069,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) return; rcu_read_lock(); - net = dev_net_rcu(dst_dev(dst)); + net = dst_dev_net_rcu(dst); if (mtu < net->ipv4.ip_rt_min_pmtu) { lock = true; mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu); @@ -1367,7 +1367,7 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst) struct net *net; rcu_read_lock(); - net = dev_net_rcu(dst_dev(dst)); + net = dst_dev_net_rcu(dst); advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size, net->ipv4.ip_rt_min_advmss); rcu_read_unlock(); -- 2.55.0