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26 results

pvr_device.c

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  • pm.c 5.55 KiB
    // SPDX-License-Identifier: GPL-2.0
    /* Multipath TCP
     *
     * Copyright (c) 2019, Intel Corporation.
     */
    #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();
    }