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Message-ID: <20250616233417.1153427-15-kuni1840@gmail.com>
Date: Mon, 16 Jun 2025 16:28:43 -0700
From: Kuniyuki Iwashima <kuni1840@...il.com>
To: "David S. Miller" <davem@...emloft.net>,
David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>,
Kuniyuki Iwashima <kuniyu@...gle.com>,
Kuniyuki Iwashima <kuni1840@...il.com>,
netdev@...r.kernel.org
Subject: [PATCH v1 net-next 14/15] ipv6: anycast: Don't hold RTNL for IPV6_JOIN_ANYCAST.
From: Kuniyuki Iwashima <kuniyu@...gle.com>
inet6_sk(sk)->ipv6_ac_list is protected by lock_sock().
In ipv6_sock_ac_join(), only __dev_get_by_index(), __dev_get_by_flags(),
and __in6_dev_get() require RTNL.
__dev_get_by_flags() is only used by ipv6_sock_ac_join() and can be
converted to RCU version.
Let's replace RCU version helper and drop RTNL from IPV6_JOIN_ANYCAST.
setsockopt_needs_rtnl() will be removed in the next patch.
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
include/linux/netdevice.h | 4 ++--
net/core/dev.c | 30 +++++++++++++++---------------
net/ipv6/anycast.c | 17 ++++++++++-------
net/ipv6/ipv6_sockglue.c | 4 ----
4 files changed, 27 insertions(+), 28 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9cbc4e54b7e4..ec410f434d39 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3329,8 +3329,8 @@ int dev_get_iflink(const struct net_device *dev);
int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb);
int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
struct net_device_path_stack *stack);
-struct net_device *__dev_get_by_flags(struct net *net, unsigned short flags,
- unsigned short mask);
+struct net_device *dev_get_by_flags(struct net *net, unsigned short flags,
+ unsigned short mask);
struct net_device *dev_get_by_name(struct net *net, const char *name);
struct net_device *dev_get_by_name_rcu(struct net *net, const char *name);
struct net_device *__dev_get_by_name(struct net *net, const char *name);
diff --git a/net/core/dev.c b/net/core/dev.c
index 5baa4691074f..17b57f1990b3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1267,33 +1267,33 @@ struct net_device *dev_getfirstbyhwtype(struct net *net, unsigned short type)
EXPORT_SYMBOL(dev_getfirstbyhwtype);
/**
- * __dev_get_by_flags - find any device with given flags
- * @net: the applicable net namespace
- * @if_flags: IFF_* values
- * @mask: bitmask of bits in if_flags to check
+ * dev_get_by_flags - find any device with given flags
+ * @net: the applicable net namespace
+ * @if_flags: IFF_* values
+ * @mask: bitmask of bits in if_flags to check
+ *
+ * Search for any interface with the given flags.
*
- * Search for any interface with the given flags. Returns NULL if a device
- * is not found or a pointer to the device. Must be called inside
- * rtnl_lock(), and result refcount is unchanged.
+ * Returns: NULL if a device is not found or a pointer to the device.
*/
-
-struct net_device *__dev_get_by_flags(struct net *net, unsigned short if_flags,
- unsigned short mask)
+struct net_device *dev_get_by_flags(struct net *net, unsigned short if_flags,
+ unsigned short mask)
{
- struct net_device *dev, *ret;
-
- ASSERT_RTNL();
+ struct net_device *dev, *ret = NULL;
- ret = NULL;
+ rcu_read_lock();
for_each_netdev(net, dev) {
if (((dev->flags ^ if_flags) & mask) == 0) {
ret = dev;
+ dev_hold(ret);
break;
}
}
+ rcu_read_unlock();
+
return ret;
}
-EXPORT_SYMBOL(__dev_get_by_flags);
+EXPORT_IPV6_MOD(dev_get_by_flags);
/**
* dev_valid_name - check if name is okay for network device
diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index e0a1f9d7622c..954c8cbb70f9 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -73,15 +73,13 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
struct inet6_dev *idev;
int err = 0, ishost;
- ASSERT_RTNL();
-
if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
return -EPERM;
if (ipv6_addr_is_multicast(addr))
return -EINVAL;
if (ifindex)
- dev = __dev_get_by_index(net, ifindex);
+ dev = dev_get_by_index(net, ifindex);
if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE)) {
err = -EINVAL;
@@ -105,14 +103,15 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
rt = rt6_lookup(net, addr, NULL, 0, NULL, 0);
if (rt) {
dev = rt->dst.dev;
+ dev_hold(dev);
ip6_rt_put(rt);
} else if (ishost) {
err = -EADDRNOTAVAIL;
goto error;
} else {
/* router, no matching interface: just pick one */
- dev = __dev_get_by_flags(net, IFF_UP,
- IFF_UP | IFF_LOOPBACK);
+ dev = dev_get_by_flags(net, IFF_UP,
+ IFF_UP | IFF_LOOPBACK);
}
}
@@ -121,7 +120,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
goto error;
}
- idev = __in6_dev_get(dev);
+ idev = in6_dev_get(dev);
if (!idev) {
if (ifindex)
err = -ENODEV;
@@ -143,7 +142,7 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
if (ishost)
err = -EADDRNOTAVAIL;
if (err)
- goto error;
+ goto error_idev;
}
err = __ipv6_dev_ac_inc(idev, addr);
@@ -153,7 +152,11 @@ int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr)
pac = NULL;
}
+error_idev:
+ in6_dev_put(idev);
error:
+ dev_put(dev);
+
if (pac)
sock_kfree_s(sk, pac, sizeof(*pac));
return err;
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 3d891aa6e7f5..702dc33e50ad 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -119,10 +119,6 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk,
static bool setsockopt_needs_rtnl(int optname)
{
- switch (optname) {
- case IPV6_JOIN_ANYCAST:
- return true;
- }
return false;
}
--
2.49.0
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