1 files changed, 244 insertions, 0 deletions
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
new file mode 100644
index 000000000000..977d9c8b1453
--- /dev/null
+++ b/net/mptcp/pm.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2019, Intel Corporation.
+ */
+#define pr_fmt(fmt) "MPTCP: " fmt
+
+#include <linux/kernel.h>
+#include <net/tcp.h>
+#include <net/mptcp.h>
+#include "protocol.h"
+
+static struct workqueue_struct *pm_wq;
+
+/* path manager command handlers */
+
+int mptcp_pm_announce_addr(struct mptcp_sock *msk,
+			   const struct mptcp_addr_info *addr)
+{
+	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)
+{
+	return -ENOTSUPP;
+}
+
+int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id)
+{
+	return -ENOTSUPP;
+}
+
+/* path manager event handlers */
+
+void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
+{
+	struct mptcp_pm_data *pm = &msk->pm;
+
+	pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
+
+	WRITE_ONCE(pm->server_side, server_side);
+}
+
+bool mptcp_pm_allow_new_subflow(struct mptcp_sock *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)
+{
+	pr_debug("msk=%p", 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)
+{
+	pr_debug("msk=%p", msk);
+}
+
+void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
+				const struct mptcp_addr_info *addr)
+{
+	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 */
+
+bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
+			  struct mptcp_addr_info *saddr)
+{
+	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)
+{
+	return mptcp_pm_nl_get_local_id(msk, 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);
+		mptcp_pm_nl_add_addr_received(msk);
+	}
+	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
+		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
+		mptcp_pm_nl_fully_established(msk);
+	}
+	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
+		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
+		mptcp_pm_nl_subflow_established(msk);
+	}
+
+	spin_unlock_bh(&msk->pm.lock);
+	release_sock(sk);
+	sock_put(sk);
+}
+
+void mptcp_pm_data_init(struct mptcp_sock *msk)
+{
+	msk->pm.add_addr_signaled = 0;
+	msk->pm.add_addr_accepted = 0;
+	msk->pm.local_addr_used = 0;
+	msk->pm.subflows = 0;
+	WRITE_ONCE(msk->pm.work_pending, false);
+	WRITE_ONCE(msk->pm.addr_signal, false);
+	WRITE_ONCE(msk->pm.accept_addr, false);
+	WRITE_ONCE(msk->pm.accept_subflow, false);
+	msk->pm.status = 0;
+
+	spin_lock_init(&msk->pm.lock);
+	INIT_WORK(&msk->pm.work, pm_worker);
+
+	mptcp_pm_nl_data_init(msk);
+}
+
+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);
+	if (!pm_wq)
+		panic("Failed to allocate workqueue");
+
+	mptcp_pm_nl_init();
+}