diff mbox series

[net-next,v3,12/15] mptcp: pm: reuse sending nlmsg code in get_addr

Message ID 20250207-net-next-mptcp-pm-misc-cleanup-2-v3-12-71753ed957de@kernel.org (mailing list archive)
State Accepted
Commit 8556f4aecc9a0620c1e411d6da1fe232d1c14138
Delegated to: Netdev Maintainers
Headers show
Series mptcp: pm: misc cleanups, part 2 | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 19 this patch: 19
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 3 this patch: 3
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 192 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-07--21-00 (tests: 890)

Commit Message

Matthieu Baerts Feb. 7, 2025, 1:59 p.m. UTC 
From: Geliang Tang <tanggeliang@kylinos.cn>

The netlink messages are sent both in mptcp_pm_nl_get_addr() and
mptcp_userspace_pm_get_addr(), this makes the code somewhat repetitive.
This is because the netlink PM and userspace PM use different locks to
protect the address entry that needs to be sent via the netlink message.
The former uses rcu read lock, and the latter uses msk->pm.lock.

The current get_addr() flow looks like this:

	lock();
	entry = get_entry();
	send_nlmsg(entry);
	unlock();

After holding the lock, get the entry from the list, send the entry, and
finally release the lock.

This patch changes the process by getting the entry while holding the lock,
then making a copy of the entry so that the lock can be released. Finally,
the copy of the entry is sent without locking:

	lock();
	entry = get_entry();
	*copy = *entry;
	unlock();

	send_nlmsg(copy);

This way we can reuse the send_nlmsg() code in get_addr() interfaces
between the netlink PM and userspace PM. They only need to implement their
own get_addr() interfaces to hold the different locks, get the entry from
the different lists, then release the locks.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/pm.c           | 39 +++++++++++++++++++++++++++++++++++----
 net/mptcp/pm_netlink.c   | 40 ++++++----------------------------------
 net/mptcp/pm_userspace.c | 42 +++++-------------------------------------
 net/mptcp/protocol.h     |  6 ++++--
 4 files changed, 50 insertions(+), 77 deletions(-)

Comments

Simon Horman Feb. 10, 2025, 7:52 p.m. UTC | #1 
On Fri, Feb 07, 2025 at 02:59:30PM +0100, Matthieu Baerts (NGI0) wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> The netlink messages are sent both in mptcp_pm_nl_get_addr() and
> mptcp_userspace_pm_get_addr(), this makes the code somewhat repetitive.
> This is because the netlink PM and userspace PM use different locks to
> protect the address entry that needs to be sent via the netlink message.
> The former uses rcu read lock, and the latter uses msk->pm.lock.
> 
> The current get_addr() flow looks like this:
> 
> 	lock();
> 	entry = get_entry();
> 	send_nlmsg(entry);
> 	unlock();
> 
> After holding the lock, get the entry from the list, send the entry, and
> finally release the lock.
> 
> This patch changes the process by getting the entry while holding the lock,
> then making a copy of the entry so that the lock can be released. Finally,
> the copy of the entry is sent without locking:
> 
> 	lock();
> 	entry = get_entry();
> 	*copy = *entry;
> 	unlock();
> 
> 	send_nlmsg(copy);
> 
> This way we can reuse the send_nlmsg() code in get_addr() interfaces
> between the netlink PM and userspace PM. They only need to implement their
> own get_addr() interfaces to hold the different locks, get the entry from
> the different lists, then release the locks.
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

Reviewed-by: Simon Horman <horms@kernel.org>
diff mbox series

Patch

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index caf5bfc3cd1ddeb22799c28dec3d19b30467b169..ba22d17c145186476c984d1eb27b102af986a0cd 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -434,17 +434,20 @@  bool mptcp_pm_is_backup(struct mptcp_sock *msk, struct sock_common *skc)
 	return mptcp_pm_nl_is_backup(msk, &skc_local);
 }
 
-static int mptcp_pm_get_addr(u8 id, struct genl_info *info)
+static int mptcp_pm_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
+			     struct genl_info *info)
 {
 	if (info->attrs[MPTCP_PM_ATTR_TOKEN])
-		return mptcp_userspace_pm_get_addr(id, info);
-	return mptcp_pm_nl_get_addr(id, info);
+		return mptcp_userspace_pm_get_addr(id, addr, info);
+	return mptcp_pm_nl_get_addr(id, addr, info);
 }
 
 int mptcp_pm_nl_get_addr_doit(struct sk_buff *skb, struct genl_info *info)
 {
 	struct mptcp_pm_addr_entry addr;
 	struct nlattr *attr;
+	struct sk_buff *msg;
+	void *reply;
 	int ret;
 
 	if (GENL_REQ_ATTR_CHECK(info, MPTCP_PM_ENDPOINT_ADDR))
@@ -455,7 +458,35 @@  int mptcp_pm_nl_get_addr_doit(struct sk_buff *skb, struct genl_info *info)
 	if (ret < 0)
 		return ret;
 
-	return mptcp_pm_get_addr(addr.addr.id, info);
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
+				  info->genlhdr->cmd);
+	if (!reply) {
+		GENL_SET_ERR_MSG(info, "not enough space in Netlink message");
+		ret = -EMSGSIZE;
+		goto fail;
+	}
+
+	ret = mptcp_pm_get_addr(addr.addr.id, &addr, info);
+	if (ret) {
+		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
+		goto fail;
+	}
+
+	ret = mptcp_nl_fill_addr(msg, &addr);
+	if (ret)
+		goto fail;
+
+	genlmsg_end(msg, reply);
+	ret = genlmsg_reply(msg, info);
+	return ret;
+
+fail:
+	nlmsg_free(msg);
+	return ret;
 }
 
 static int mptcp_pm_dump_addr(struct sk_buff *msg, struct netlink_callback *cb)
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 5a6c33d0063df7e741b9a83a624099adab1611f6..25b66674171fc39d73d88948ba952816b504051e 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1773,49 +1773,21 @@  int mptcp_nl_fill_addr(struct sk_buff *skb,
 	return -EMSGSIZE;
 }
 
-int mptcp_pm_nl_get_addr(u8 id, struct genl_info *info)
+int mptcp_pm_nl_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
+			 struct genl_info *info)
 {
-	struct nlattr *attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct pm_nl_pernet *pernet = genl_info_pm_nl(info);
 	struct mptcp_pm_addr_entry *entry;
-	struct sk_buff *msg;
-	void *reply;
-	int ret;
-
-	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-	if (!msg)
-		return -ENOMEM;
-
-	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
-				  info->genlhdr->cmd);
-	if (!reply) {
-		GENL_SET_ERR_MSG(info, "not enough space in Netlink message");
-		ret = -EMSGSIZE;
-		goto fail;
-	}
+	int ret = -EINVAL;
 
 	rcu_read_lock();
 	entry = __lookup_addr_by_id(pernet, id);
-	if (!entry) {
-		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
-		ret = -EINVAL;
-		goto unlock_fail;
+	if (entry) {
+		*addr = *entry;
+		ret = 0;
 	}
-
-	ret = mptcp_nl_fill_addr(msg, entry);
-	if (ret)
-		goto unlock_fail;
-
-	genlmsg_end(msg, reply);
-	ret = genlmsg_reply(msg, info);
-	rcu_read_unlock();
-	return ret;
-
-unlock_fail:
 	rcu_read_unlock();
 
-fail:
-	nlmsg_free(msg);
 	return ret;
 }
 
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 99e882a5a67180bc912818ec0952fd50ed601ac4..80d75df18b039dc60ca5c4432da44a1a9dbf33f1 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -684,15 +684,13 @@  int mptcp_userspace_pm_dump_addr(struct sk_buff *msg,
 	return ret;
 }
 
-int mptcp_userspace_pm_get_addr(u8 id, struct genl_info *info)
+int mptcp_userspace_pm_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
+				struct genl_info *info)
 {
-	struct nlattr *attr = attr = info->attrs[MPTCP_PM_ENDPOINT_ADDR];
 	struct mptcp_pm_addr_entry *entry;
 	struct mptcp_sock *msk;
-	struct sk_buff *msg;
 	int ret = -EINVAL;
 	struct sock *sk;
-	void *reply;
 
 	msk = mptcp_userspace_pm_get_sock(info);
 	if (!msk)
@@ -700,46 +698,16 @@  int mptcp_userspace_pm_get_addr(u8 id, struct genl_info *info)
 
 	sk = (struct sock *)msk;
 
-	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-	if (!msg) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	reply = genlmsg_put_reply(msg, info, &mptcp_genl_family, 0,
-				  info->genlhdr->cmd);
-	if (!reply) {
-		GENL_SET_ERR_MSG(info, "not enough space in Netlink message");
-		ret = -EMSGSIZE;
-		goto fail;
-	}
-
 	lock_sock(sk);
 	spin_lock_bh(&msk->pm.lock);
 	entry = mptcp_userspace_pm_lookup_addr_by_id(msk, id);
-	if (!entry) {
-		NL_SET_ERR_MSG_ATTR(info->extack, attr, "address not found");
-		ret = -EINVAL;
-		goto unlock_fail;
+	if (entry) {
+		*addr = *entry;
+		ret = 0;
 	}
-
-	ret = mptcp_nl_fill_addr(msg, entry);
-	if (ret)
-		goto unlock_fail;
-
-	genlmsg_end(msg, reply);
-	ret = genlmsg_reply(msg, info);
 	spin_unlock_bh(&msk->pm.lock);
 	release_sock(sk);
-	sock_put(sk);
-	return ret;
 
-unlock_fail:
-	spin_unlock_bh(&msk->pm.lock);
-	release_sock(sk);
-fail:
-	nlmsg_free(msg);
-out:
 	sock_put(sk);
 	return ret;
 }
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ffe370245ec55fe64b1215b48878d1bdaabd3248..e18ecd77a7f76b5e4d010170532f7b9e913ec78b 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1134,8 +1134,10 @@  int mptcp_pm_nl_dump_addr(struct sk_buff *msg,
 			  struct netlink_callback *cb);
 int mptcp_userspace_pm_dump_addr(struct sk_buff *msg,
 				 struct netlink_callback *cb);
-int mptcp_pm_nl_get_addr(u8 id, struct genl_info *info);
-int mptcp_userspace_pm_get_addr(u8 id, struct genl_info *info);
+int mptcp_pm_nl_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
+			 struct genl_info *info);
+int mptcp_userspace_pm_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
+				struct genl_info *info);
 
 static inline u8 subflow_get_local_id(const struct mptcp_subflow_context *subflow)
 {