From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds a .subflow_established interface for struct mptcp_pm_ops,
and calls pm->ops->subflow_established in from mptcp_pm_worker(). Then
get rid of the corresponding code from __mptcp_pm_kernel_worker().

Since mptcp_pm_addr_send_ack() is a sleepable kfunc, which is invoked
by mptcp_pm_create_subflow_or_signal_addr(), .subflow_established()
interface of BPF PM should be invoked by __bpf_prog_enter_sleepable(),
which can't be invoked under a lock. This patch unlocks the pm lock
before invoking this interface in mptcp_pm_worker(), while holding this
lock in mptcp_pm_kernel_subflow_established().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/mptcp.h   |  1 +
 net/mptcp/pm.c        | 13 ++++++++++---
 net/mptcp/pm_kernel.c |  9 +++------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 97a237c9bfe0..1eae68c9e662 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -127,6 +127,7 @@ struct mptcp_pm_ops {
 
 	/* optional, call from the msk context */
 	void (*established)(struct mptcp_sock *msk);
+	void (*subflow_established)(struct mptcp_sock *msk);
 
 	char			name[MPTCP_PM_NAME_MAX];
 	struct module		*owner;
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 8dcf61a77b7d..39842f7786db 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -533,7 +533,7 @@ void mptcp_pm_subflow_established(struct mptcp_sock *msk)
 
 	pr_debug("msk=%p\n", msk);
 
-	if (!READ_ONCE(pm->work_pending))
+	if (!READ_ONCE(pm->work_pending) || !pm->ops->subflow_established)
 		return;
 
 	spin_lock_bh(&pm->lock);
@@ -560,7 +560,8 @@ void mptcp_pm_subflow_check_next(struct mptcp_sock *msk,
 		return;
 	}
 
-	if (!READ_ONCE(pm->work_pending) && !update_subflows)
+	if (!pm->ops->subflow_established ||
+	    (!READ_ONCE(pm->work_pending) && !update_subflows))
 		return;
 
 	spin_lock_bh(&pm->lock);
@@ -618,7 +619,7 @@ void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
 
 	pr_debug("msk=%p\n", msk);
 
-	if (!READ_ONCE(pm->work_pending))
+	if (!READ_ONCE(pm->work_pending) || !pm->ops->subflow_established)
 		return;
 
 	spin_lock_bh(&pm->lock);
@@ -963,6 +964,12 @@ void mptcp_pm_worker(struct mptcp_sock *msk)
 		spin_unlock_bh(&pm->lock);
 		pm->ops->established(msk);
 	}
+	if (status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
+		spin_lock_bh(&pm->lock);
+		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
+		spin_unlock_bh(&pm->lock);
+		pm->ops->subflow_established(msk);
+	}
 	spin_lock_bh(&pm->lock);
 	__mptcp_pm_kernel_worker(msk);
 	spin_unlock_bh(&pm->lock);
diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
index 5444565c8cf2..e37cee9d38d7 100644
--- a/net/mptcp/pm_kernel.c
+++ b/net/mptcp/pm_kernel.c
@@ -379,9 +379,9 @@ static void mptcp_pm_kernel_established(struct mptcp_sock *msk)
 	mptcp_pm_create_subflow_or_signal_addr(msk);
 }
 
-static void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk)
+static void mptcp_pm_kernel_subflow_established(struct mptcp_sock *msk)
 {
-	__mptcp_pm_create_subflow_or_signal_addr(msk);
+	mptcp_pm_create_subflow_or_signal_addr(msk);
 }
 
 /* Fill all the local addresses into the array addrs[],
@@ -1355,10 +1355,6 @@ void __mptcp_pm_kernel_worker(struct mptcp_sock *msk)
 		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
 		mptcp_pm_nl_add_addr_received(msk);
 	}
-	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
-		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
-		mptcp_pm_nl_subflow_established(msk);
-	}
 }
 
 static int __net_init pm_nl_init_net(struct net *net)
@@ -1451,6 +1447,7 @@ struct mptcp_pm_ops mptcp_pm_kernel = {
 	.get_priority		= mptcp_pm_kernel_get_priority,
 	.accept_new_subflow	= mptcp_pm_kernel_accept_new_subflow,
 	.established		= mptcp_pm_kernel_established,
+	.subflow_established	= mptcp_pm_kernel_subflow_established,
 	.init			= mptcp_pm_kernel_init,
 	.name			= "kernel",
 	.owner			= THIS_MODULE,
-- 
2.43.0