net/mptcp/pm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Multipath TCP
   3  *
   4  * Copyright (c) 2019, Intel Corporation.
   5  */
   6 #define pr_fmt(fmt) "MPTCP: " fmt
   7
   8 #include <linux/kernel.h>
   9 #include <net/tcp.h>
  10 #include <net/mptcp.h>
  11 #include "protocol.h"
  12
  13 static struct workqueue_struct *pm_wq;
  14
  15 /* path manager command handlers */
  16
  17 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
  18                            const struct mptcp_addr_info *addr)
  19 {
  20         pr_debug("msk=%p, local_id=%d", msk, addr->id);
  21
  22         msk->pm.local = *addr;
  23         WRITE_ONCE(msk->pm.addr_signal, true);
  24         return 0;
  25 }
  26
  27 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
  28 {
  29         return -ENOTSUPP;
  30 }
  31
  32 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id)
  33 {
  34         return -ENOTSUPP;
  35 }
  36
  37 /* path manager event handlers */
  38
  39 void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
  40 {
  41         struct mptcp_pm_data *pm = &msk->pm;
  42
  43         pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
  44
  45         WRITE_ONCE(pm->server_side, server_side);
  46 }
  47
  48 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
  49 {
  50         struct mptcp_pm_data *pm = &msk->pm;
  51         int ret;
  52
  53         pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
  54                  pm->subflows_max, READ_ONCE(pm->accept_subflow));
  55
  56         /* try to avoid acquiring the lock below */
  57         if (!READ_ONCE(pm->accept_subflow))
  58                 return false;
  59
  60         spin_lock_bh(&pm->lock);
  61         ret = pm->subflows < pm->subflows_max;
  62         if (ret && ++pm->subflows == pm->subflows_max)
  63                 WRITE_ONCE(pm->accept_subflow, false);
  64         spin_unlock_bh(&pm->lock);
  65
  66         return ret;
  67 }
  68
  69 /* return true if the new status bit is currently cleared, that is, this event
  70  * can be server, eventually by an already scheduled work
  71  */
  72 static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
  73                                    enum mptcp_pm_status new_status)
  74 {
  75         pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
  76                  BIT(new_status));
  77         if (msk->pm.status & BIT(new_status))
  78                 return false;
  79
  80         msk->pm.status |= BIT(new_status);
  81         if (queue_work(pm_wq, &msk->pm.work))
  82                 sock_hold((struct sock *)msk);
  83         return true;
  84 }
  85
  86 void mptcp_pm_fully_established(struct mptcp_sock *msk)
  87 {
  88         struct mptcp_pm_data *pm = &msk->pm;
  89
  90         pr_debug("msk=%p", msk);
  91
  92         /* try to avoid acquiring the lock below */
  93         if (!READ_ONCE(pm->work_pending))
  94                 return;
  95
  96         spin_lock_bh(&pm->lock);
  97
  98         if (READ_ONCE(pm->work_pending))
  99                 mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 100
 101         spin_unlock_bh(&pm->lock);
 102 }
 103
 104 void mptcp_pm_connection_closed(struct mptcp_sock *msk)
 105 {
 106         pr_debug("msk=%p", msk);
 107 }
 108
 109 void mptcp_pm_subflow_established(struct mptcp_sock *msk,
 110                                   struct mptcp_subflow_context *subflow)
 111 {
 112         struct mptcp_pm_data *pm = &msk->pm;
 113
 114         pr_debug("msk=%p", msk);
 115
 116         if (!READ_ONCE(pm->work_pending))
 117                 return;
 118
 119         spin_lock_bh(&pm->lock);
 120
 121         if (READ_ONCE(pm->work_pending))
 122                 mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
 123
 124         spin_unlock_bh(&pm->lock);
 125 }
 126
 127 void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
 128 {
 129         pr_debug("msk=%p", msk);
 130 }
 131
 132 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 133                                 const struct mptcp_addr_info *addr)
 134 {
 135         struct mptcp_pm_data *pm = &msk->pm;
 136
 137         pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
 138                  READ_ONCE(pm->accept_addr));
 139
 140         /* avoid acquiring the lock if there is no room for fouther addresses */
 141         if (!READ_ONCE(pm->accept_addr))
 142                 return;
 143
 144         spin_lock_bh(&pm->lock);
 145
 146         /* be sure there is something to signal re-checking under PM lock */
 147         if (READ_ONCE(pm->accept_addr) &&
 148             mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED))
 149                 pm->remote = *addr;
 150
 151         spin_unlock_bh(&pm->lock);
 152 }
 153
 154 /* path manager helpers */
 155
 156 bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 157                           struct mptcp_addr_info *saddr)
 158 {
 159         int ret = false;
 160
 161         spin_lock_bh(&msk->pm.lock);
 162
 163         /* double check after the lock is acquired */
 164         if (!mptcp_pm_should_signal(msk))
 165                 goto out_unlock;
 166
 167         if (remaining < mptcp_add_addr_len(msk->pm.local.family))
 168                 goto out_unlock;
 169
 170         *saddr = msk->pm.local;
 171         WRITE_ONCE(msk->pm.addr_signal, false);
 172         ret = true;
 173
 174 out_unlock:
 175         spin_unlock_bh(&msk->pm.lock);
 176         return ret;
 177 }
 178
 179 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 180 {
 181         return mptcp_pm_nl_get_local_id(msk, skc);
 182 }
 183
 184 static void pm_worker(struct work_struct *work)
 185 {
 186         struct mptcp_pm_data *pm = container_of(work, struct mptcp_pm_data,
 187                                                 work);
 188         struct mptcp_sock *msk = container_of(pm, struct mptcp_sock, pm);
 189         struct sock *sk = (struct sock *)msk;
 190
 191         lock_sock(sk);
 192         spin_lock_bh(&msk->pm.lock);
 193
 194         pr_debug("msk=%p status=%x", msk, pm->status);
 195         if (pm->status & BIT(MPTCP_PM_ADD_ADDR_RECEIVED)) {
 196                 pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
 197                 mptcp_pm_nl_add_addr_received(msk);
 198         }
 199         if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
 200                 pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
 201                 mptcp_pm_nl_fully_established(msk);
 202         }
 203         if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
 204                 pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
 205                 mptcp_pm_nl_subflow_established(msk);
 206         }
 207
 208         spin_unlock_bh(&msk->pm.lock);
 209         release_sock(sk);
 210         sock_put(sk);
 211 }
 212
 213 void mptcp_pm_data_init(struct mptcp_sock *msk)
 214 {
 215         msk->pm.add_addr_signaled = 0;
 216         msk->pm.add_addr_accepted = 0;
 217         msk->pm.local_addr_used = 0;
 218         msk->pm.subflows = 0;
 219         WRITE_ONCE(msk->pm.work_pending, false);
 220         WRITE_ONCE(msk->pm.addr_signal, false);
 221         WRITE_ONCE(msk->pm.accept_addr, false);
 222         WRITE_ONCE(msk->pm.accept_subflow, false);
 223         msk->pm.status = 0;
 224
 225         spin_lock_init(&msk->pm.lock);
 226         INIT_WORK(&msk->pm.work, pm_worker);
 227
 228         mptcp_pm_nl_data_init(msk);
 229 }
 230
 231 void mptcp_pm_close(struct mptcp_sock *msk)
 232 {
 233         if (cancel_work_sync(&msk->pm.work))
 234                 sock_put((struct sock *)msk);
 235 }
 236
 237 void mptcp_pm_init(void)
 238 {
 239         pm_wq = alloc_workqueue("pm_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);
 240         if (!pm_wq)
 241                 panic("Failed to allocate workqueue");
 242
 243         mptcp_pm_nl_init();
 244 }