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Message-ID: <20240122112603.3270097-8-edumazet@google.com>
Date: Mon, 22 Jan 2024 11:26:01 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>,
Martin KaFai Lau <kafai@...com>, Guillaume Nault <gnault@...hat.com>, netdev@...r.kernel.org,
eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 7/9] sock_diag: allow concurrent operation in sock_diag_rcv_msg()
TCPDIAG_GETSOCK and DCCPDIAG_GETSOCK diag are serialized
on sock_diag_table_mutex.
This is to make sure inet_diag module is not unloaded
while diag was ongoing.
It is time to get rid of this mutex and use RCU protection,
allowing full parallelism.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/linux/sock_diag.h | 9 ++++++--
net/core/sock_diag.c | 43 +++++++++++++++++++++++----------------
net/ipv4/inet_diag.c | 9 ++++++--
3 files changed, 40 insertions(+), 21 deletions(-)
diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index 7c07754d711b9bd04bc57f8ed08981849fcadb11..110978dc9af1b19194644151af5456b8c6644cf9 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -23,8 +23,13 @@ struct sock_diag_handler {
int sock_diag_register(const struct sock_diag_handler *h);
void sock_diag_unregister(const struct sock_diag_handler *h);
-void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
-void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));
+struct sock_diag_inet_compat {
+ struct module *owner;
+ int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh);
+};
+
+void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr);
+void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr);
u64 __sock_gen_cookie(struct sock *sk);
diff --git a/net/core/sock_diag.c b/net/core/sock_diag.c
index 72009e1f4380dfdcbf43ed08791e5039e74f5c54..5c3666431df49b3c278ef795f11ba542247796a6 100644
--- a/net/core/sock_diag.c
+++ b/net/core/sock_diag.c
@@ -17,8 +17,9 @@
#include <linux/sock_diag.h>
static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX];
-static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);
-static DEFINE_MUTEX(sock_diag_table_mutex);
+
+static struct sock_diag_inet_compat __rcu *inet_rcv_compat;
+
static struct workqueue_struct *broadcast_wq;
DEFINE_COOKIE(sock_cookie);
@@ -184,19 +185,20 @@ void sock_diag_broadcast_destroy(struct sock *sk)
queue_work(broadcast_wq, &bsk->work);
}
-void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
+void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr)
{
- mutex_lock(&sock_diag_table_mutex);
- inet_rcv_compat = fn;
- mutex_unlock(&sock_diag_table_mutex);
+ xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,
+ ptr);
}
EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);
-void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
+void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr)
{
- mutex_lock(&sock_diag_table_mutex);
- inet_rcv_compat = NULL;
- mutex_unlock(&sock_diag_table_mutex);
+ const struct sock_diag_inet_compat *old;
+
+ old = xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,
+ NULL);
+ WARN_ON_ONCE(old != ptr);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);
@@ -259,20 +261,27 @@ static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh)
static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
+ const struct sock_diag_inet_compat *ptr;
int ret;
switch (nlh->nlmsg_type) {
case TCPDIAG_GETSOCK:
case DCCPDIAG_GETSOCK:
- if (inet_rcv_compat == NULL)
+
+ if (!rcu_access_pointer(inet_rcv_compat))
sock_load_diag_module(AF_INET, 0);
- mutex_lock(&sock_diag_table_mutex);
- if (inet_rcv_compat != NULL)
- ret = inet_rcv_compat(skb, nlh);
- else
- ret = -EOPNOTSUPP;
- mutex_unlock(&sock_diag_table_mutex);
+ rcu_read_lock();
+ ptr = rcu_dereference(inet_rcv_compat);
+ if (ptr && !try_module_get(ptr->owner))
+ ptr = NULL;
+ rcu_read_unlock();
+
+ ret = -EOPNOTSUPP;
+ if (ptr) {
+ ret = ptr->fn(skb, nlh);
+ module_put(ptr->owner);
+ }
return ret;
case SOCK_DIAG_BY_FAMILY:
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 52ce20691e4ef1382da94473128e3c14c55bd542..2c2d8b9dd8e9bb502e52e30dffc70da36d9b1c74 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -1527,6 +1527,11 @@ void inet_diag_unregister(const struct inet_diag_handler *h)
}
EXPORT_SYMBOL_GPL(inet_diag_unregister);
+static const struct sock_diag_inet_compat inet_diag_compat = {
+ .owner = THIS_MODULE,
+ .fn = inet_diag_rcv_msg_compat,
+};
+
static int __init inet_diag_init(void)
{
const int inet_diag_table_size = (IPPROTO_MAX *
@@ -1545,7 +1550,7 @@ static int __init inet_diag_init(void)
if (err)
goto out_free_inet;
- sock_diag_register_inet_compat(inet_diag_rcv_msg_compat);
+ sock_diag_register_inet_compat(&inet_diag_compat);
out:
return err;
@@ -1560,7 +1565,7 @@ static void __exit inet_diag_exit(void)
{
sock_diag_unregister(&inet6_diag_handler);
sock_diag_unregister(&inet_diag_handler);
- sock_diag_unregister_inet_compat(inet_diag_rcv_msg_compat);
+ sock_diag_unregister_inet_compat(&inet_diag_compat);
kfree(inet_diag_table);
}
--
2.43.0.429.g432eaa2c6b-goog
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