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// 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();
}
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