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| author | Eric Dumazet <edumazet@google.com> | 2025-12-15 21:51:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-12-18 13:55:22 +0100 |
| commit | 90c47a1a526c285157be733d4b94d9b1dc339a6f (patch) | |
| tree | 53974939fc9d12780f557f7936a09afde622bd46 | |
| parent | 8401fe8638491c0c06157f7b926bed778d0fe402 (diff) | |
| download | linux-90c47a1a526c285157be733d4b94d9b1dc339a6f.tar.gz linux-90c47a1a526c285157be733d4b94d9b1dc339a6f.tar.bz2 linux-90c47a1a526c285157be733d4b94d9b1dc339a6f.zip | |
net: dst: introduce dst->dev_rcu
[ Upstream commit caedcc5b6df1b2e2b5f39079e3369c1d4d5c5f50 ]
Followup of commit 88fe14253e1818 ("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()")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250828195823.3958522-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 50c127a69cd62 ("Replace three dst_dev() with a lockdep enabled helper.")
Signed-off-by: Gyokhan Kochmarla <gyokhan@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/net/dst.h | 16 | ||||
| -rw-r--r-- | net/core/dst.c | 2 | ||||
| -rw-r--r-- | 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 e5c9ea188383..e7c1eb69570e 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -24,7 +24,10 @@ 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; @@ -568,9 +571,12 @@ 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) @@ -590,7 +596,7 @@ 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 9a0ddef8bee4..8dbb54148c03 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -150,7 +150,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev); WRITE_ONCE(dst->input, dst_discard); WRITE_ONCE(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 e219bb423c3a..7579001d5b29 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1030,7 +1030,7 @@ 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); @@ -1328,7 +1328,7 @@ 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(); |