mptcp: Implement path manager interface commands

Fill in more path manager functionality by adding a worker function and
modifying the related stub functions to schedule the worker.
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/pm.c

@@ -15,7 +15,11 @@ static struct workqueue_struct *pm_wq;
 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 			   const struct mptcp_addr_info *addr)
 {
-	return -ENOTSUPP;
+	pr_debug("msk=%p, local_id=%d", msk, addr->id);
+
+	msk->pm.local = *addr;
+	WRITE_ONCE(msk->pm.addr_signal, true);
+	return 0;
 }
 
 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
@@ -41,13 +45,58 @@ void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
 
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
 {
-	pr_debug("msk=%p", msk);
+	struct mptcp_pm_data *pm = &msk->pm;
+	int ret;
+
+	pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
+		 pm->subflows_max, READ_ONCE(pm->accept_subflow));
+
+	/* try to avoid acquiring the lock below */
+	if (!READ_ONCE(pm->accept_subflow))
+		return false;
+
+	spin_lock_bh(&pm->lock);
+	ret = pm->subflows < pm->subflows_max;
+	if (ret && ++pm->subflows == pm->subflows_max)
+		WRITE_ONCE(pm->accept_subflow, false);
+	spin_unlock_bh(&pm->lock);
+
+	return ret;
+}
+
+/* return true if the new status bit is currently cleared, that is, this event
+ * can be server, eventually by an already scheduled work
+ */
+static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
+				   enum mptcp_pm_status new_status)
+{
+	pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
+		 BIT(new_status));
+	if (msk->pm.status & BIT(new_status))
 		return false;
+
+	msk->pm.status |= BIT(new_status);
+	if (queue_work(pm_wq, &msk->pm.work))
+		sock_hold((struct sock *)msk);
+	return true;
 }
 
 void mptcp_pm_fully_established(struct mptcp_sock *msk)
 {
+	struct mptcp_pm_data *pm = &msk->pm;
+
 	pr_debug("msk=%p", msk);
+
+	/* try to avoid acquiring the lock below */
+	if (!READ_ONCE(pm->work_pending))
+		return;
+
+	spin_lock_bh(&pm->lock);
+
+	if (READ_ONCE(pm->work_pending))
+		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
+
+	spin_unlock_bh(&pm->lock);
 }
 
 void mptcp_pm_connection_closed(struct mptcp_sock *msk)
@@ -58,7 +107,19 @@ void mptcp_pm_connection_closed(struct mptcp_sock *msk)
 void mptcp_pm_subflow_established(struct mptcp_sock *msk,
 				  struct mptcp_subflow_context *subflow)
 {
+	struct mptcp_pm_data *pm = &msk->pm;
+
 	pr_debug("msk=%p", msk);
+
+	if (!READ_ONCE(pm->work_pending))
+		return;
+
+	spin_lock_bh(&pm->lock);
+
+	if (READ_ONCE(pm->work_pending))
+		mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
+
+	spin_unlock_bh(&pm->lock);
 }
 
 void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
@@ -69,7 +130,23 @@ void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 				const struct mptcp_addr_info *addr)
 {
-	pr_debug("msk=%p, remote_id=%d", msk, addr->id);
+	struct mptcp_pm_data *pm = &msk->pm;
+
+	pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
+		 READ_ONCE(pm->accept_addr));
+
+	/* avoid acquiring the lock if there is no room for fouther addresses */
+	if (!READ_ONCE(pm->accept_addr))
+		return;
+
+	spin_lock_bh(&pm->lock);
+
+	/* be sure there is something to signal re-checking under PM lock */
+	if (READ_ONCE(pm->accept_addr) &&
+	    mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED))
+		pm->remote = *addr;
+
+	spin_unlock_bh(&pm->lock);
 }
 
 /* path manager helpers */
@@ -77,7 +154,24 @@ void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 			  struct mptcp_addr_info *saddr)
 {
-	return false;
+	int ret = false;
+
+	spin_lock_bh(&msk->pm.lock);
+
+	/* double check after the lock is acquired */
+	if (!mptcp_pm_should_signal(msk))
+		goto out_unlock;
+
+	if (remaining < mptcp_add_addr_len(msk->pm.local.family))
+		goto out_unlock;
+
+	*saddr = msk->pm.local;
+	WRITE_ONCE(msk->pm.addr_signal, false);
+	ret = true;
+
+out_unlock:
+	spin_unlock_bh(&msk->pm.lock);
+	return ret;
 }
 
 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
@@ -87,6 +181,28 @@ int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 
 static void pm_worker(struct work_struct *work)
 {
+	struct mptcp_pm_data *pm = container_of(work, struct mptcp_pm_data,
+						work);
+	struct mptcp_sock *msk = container_of(pm, struct mptcp_sock, pm);
+	struct sock *sk = (struct sock *)msk;
+
+	lock_sock(sk);
+	spin_lock_bh(&msk->pm.lock);
+
+	pr_debug("msk=%p status=%x", msk, pm->status);
+	if (pm->status & BIT(MPTCP_PM_ADD_ADDR_RECEIVED)) {
+		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
+	}
+	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
+		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
+	}
+	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
+		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
+	}
+
+	spin_unlock_bh(&msk->pm.lock);
+	release_sock(sk);
+	sock_put(sk);
 }
 
 void mptcp_pm_data_init(struct mptcp_sock *msk)
@@ -105,6 +221,12 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
 	INIT_WORK(&msk->pm.work, pm_worker);
 }
 
+void mptcp_pm_close(struct mptcp_sock *msk)
+{
+	if (cancel_work_sync(&msk->pm.work))
+		sock_put((struct sock *)msk);
+}
+
 void mptcp_pm_init(void)
 {
 	pm_wq = alloc_workqueue("pm_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);

net/mptcp/protocol.c

@@ -833,6 +833,7 @@ static void mptcp_close(struct sock *sk, long timeout)
 	}
 
 	mptcp_cancel_work(sk);
+	mptcp_pm_close(msk);
 
 	__skb_queue_purge(&sk->sk_receive_queue);
 

net/mptcp/protocol.h

@@ -330,6 +330,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);
 
 void mptcp_pm_init(void);
 void mptcp_pm_data_init(struct mptcp_sock *msk);
+void mptcp_pm_close(struct mptcp_sock *msk);
 void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side);
 void mptcp_pm_fully_established(struct mptcp_sock *msk);
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk);