mptcp: pm: in-kernel: rename 'subflows_max' to 'limit_extra_subflows'

A few variables linked to the in-kernel Path-Manager are confusing, and
it would help current and future developers, to clarify them.

One of them is 'subflows_max', which in fact represents the limit of
extra subflows: the limit set via 'ip mptcp limit subflows X' for
example. It is not linked to the maximum number of created / possible
subflows.

While at it, add an additional name for the corresponding variable in
MPTCP INFO: mptcpi_limit_extra_subflows. Not to break the current uAPI,
the new name is added as a 'define' pointing to the former name. This
will then also help userspace devs.

No functional changes intended.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250925-net-next-mptcp-c-flag-laminar-v1-6-ad126cc47c6b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h
index f807c8dba56e7eb278fce0ad3184de3d0e24399b..314200c61f150da445ff87debb154bfd98f324fc 100644 (file)
--- a/include/uapi/linux/mptcp.h
+++ b/include/uapi/linux/mptcp.h
@@ -46,6 +46,7 @@ struct mptcp_info {
        __u8    mptcpi_add_addr_signal;
        __u8    mptcpi_add_addr_accepted;
        __u8    mptcpi_subflows_max;
+       #define mptcpi_limit_extra_subflows mptcpi_subflows_max
        __u8    mptcpi_add_addr_signal_max;
        __u8    mptcpi_add_addr_accepted_max;
        __u32   mptcpi_flags;

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 332e96bdadc0b936704188e5c9666cba97817b16..502f6c235e06c3f6fdca9dcf3a1d7b8e97fb9df6 100644 (file)
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -483,7 +483,7 @@ void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int
 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
 {
        struct mptcp_pm_data *pm = &msk->pm;
-       unsigned int subflows_max;
+       unsigned int limit_extra_subflows;
        int ret = 0;
 
        if (mptcp_pm_is_userspace(msk)) {
@@ -496,10 +496,10 @@ bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
                return false;
        }
 
-       subflows_max = mptcp_pm_get_subflows_max(msk);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        pr_debug("msk=%p subflows=%d max=%d allow=%d\n", msk,
-                pm->extra_subflows, subflows_max,
+                pm->extra_subflows, limit_extra_subflows,
                 READ_ONCE(pm->accept_subflow));
 
        /* try to avoid acquiring the lock below */
@@ -508,8 +508,8 @@ bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
 
        spin_lock_bh(&pm->lock);
        if (READ_ONCE(pm->accept_subflow)) {
-               ret = pm->extra_subflows < subflows_max;
-               if (ret && ++pm->extra_subflows == subflows_max)
+               ret = pm->extra_subflows < limit_extra_subflows;
+               if (ret && ++pm->extra_subflows == limit_extra_subflows)
                        WRITE_ONCE(pm->accept_subflow, false);
        }
        spin_unlock_bh(&pm->lock);
@@ -1029,7 +1029,7 @@ void mptcp_pm_data_reset(struct mptcp_sock *msk)
        WRITE_ONCE(pm->pm_type, pm_type);
 
        if (pm_type == MPTCP_PM_TYPE_KERNEL) {
-               bool subflows_allowed = !!mptcp_pm_get_subflows_max(msk);
+               bool subflows_allowed = !!mptcp_pm_get_limit_extra_subflows(msk);
 
                /* pm->work_pending must be only be set to 'true' when
                 * pm->pm_type is set to MPTCP_PM_TYPE_KERNEL

diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
index 20bee6fc06259a0211782c94c1693ffe79dae1b6..db0d254d0e6b903fd8b920eb4cda628a811f7d58 100644 (file)
--- a/net/mptcp/pm_kernel.c
+++ b/net/mptcp/pm_kernel.c
@@ -23,7 +23,7 @@ struct pm_nl_pernet {
        unsigned int            add_addr_signal_max;
        unsigned int            add_addr_accept_max;
        unsigned int            local_addr_max;
-       unsigned int            subflows_max;
+       unsigned int            limit_extra_subflows;
        unsigned int            next_id;
        DECLARE_BITMAP(id_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
 };
@@ -62,13 +62,13 @@ unsigned int mptcp_pm_get_add_addr_accept_max(const struct mptcp_sock *msk)
 }
 EXPORT_SYMBOL_GPL(mptcp_pm_get_add_addr_accept_max);
 
-unsigned int mptcp_pm_get_subflows_max(const struct mptcp_sock *msk)
+unsigned int mptcp_pm_get_limit_extra_subflows(const struct mptcp_sock *msk)
 {
        struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk);
 
-       return READ_ONCE(pernet->subflows_max);
+       return READ_ONCE(pernet->limit_extra_subflows);
 }
-EXPORT_SYMBOL_GPL(mptcp_pm_get_subflows_max);
+EXPORT_SYMBOL_GPL(mptcp_pm_get_limit_extra_subflows);
 
 unsigned int mptcp_pm_get_local_addr_max(const struct mptcp_sock *msk)
 {
@@ -190,10 +190,10 @@ fill_remote_addresses_fullmesh(struct mptcp_sock *msk,
        DECLARE_BITMAP(unavail_id, MPTCP_PM_MAX_ADDR_ID + 1);
        struct sock *sk = (struct sock *)msk, *ssk;
        struct mptcp_subflow_context *subflow;
-       unsigned int subflows_max;
+       unsigned int limit_extra_subflows;
        int i = 0;
 
-       subflows_max = mptcp_pm_get_subflows_max(msk);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        /* Forbid creation of new subflows matching existing ones, possibly
         * already created by incoming ADD_ADDR
@@ -221,7 +221,7 @@ fill_remote_addresses_fullmesh(struct mptcp_sock *msk,
                msk->pm.extra_subflows++;
                i++;
 
-               if (msk->pm.extra_subflows >= subflows_max)
+               if (msk->pm.extra_subflows >= limit_extra_subflows)
                        break;
        }
 
@@ -274,18 +274,18 @@ __lookup_addr(struct pm_nl_pernet *pernet, const struct mptcp_addr_info *info)
 static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 {
        struct sock *sk = (struct sock *)msk;
+       unsigned int limit_extra_subflows;
        unsigned int add_addr_signal_max;
        bool signal_and_subflow = false;
        unsigned int local_addr_max;
        struct pm_nl_pernet *pernet;
        struct mptcp_pm_local local;
-       unsigned int subflows_max;
 
        pernet = pm_nl_get_pernet(sock_net(sk));
 
        add_addr_signal_max = mptcp_pm_get_add_addr_signal_max(msk);
        local_addr_max = mptcp_pm_get_local_addr_max(msk);
-       subflows_max = mptcp_pm_get_subflows_max(msk);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        /* do lazy endpoint usage accounting for the MPC subflows */
        if (unlikely(!(msk->pm.status & BIT(MPTCP_PM_MPC_ENDPOINT_ACCOUNTED))) && msk->first) {
@@ -313,7 +313,7 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
        pr_debug("local %d:%d signal %d:%d subflows %d:%d\n",
                 msk->pm.local_addr_used, local_addr_max,
                 msk->pm.add_addr_signaled, add_addr_signal_max,
-                msk->pm.extra_subflows, subflows_max);
+                msk->pm.extra_subflows, limit_extra_subflows);
 
        /* check first for announce */
        if (msk->pm.add_addr_signaled < add_addr_signal_max) {
@@ -353,7 +353,7 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 subflow:
        /* check if should create a new subflow */
        while (msk->pm.local_addr_used < local_addr_max &&
-              msk->pm.extra_subflows < subflows_max) {
+              msk->pm.extra_subflows < limit_extra_subflows) {
                struct mptcp_addr_info addrs[MPTCP_PM_ADDR_MAX];
                bool fullmesh;
                int i, nr;
@@ -402,14 +402,15 @@ fill_local_addresses_vec_fullmesh(struct mptcp_sock *msk,
                                  bool c_flag_case)
 {
        struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk);
-       unsigned int subflows_max = mptcp_pm_get_subflows_max(msk);
        struct sock *sk = (struct sock *)msk;
        struct mptcp_pm_addr_entry *entry;
+       unsigned int limit_extra_subflows;
        struct mptcp_addr_info mpc_addr;
        struct mptcp_pm_local *local;
        int i = 0;
 
        mptcp_local_address((struct sock_common *)msk, &mpc_addr);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        rcu_read_lock();
        list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
@@ -444,7 +445,7 @@ fill_local_addresses_vec_fullmesh(struct mptcp_sock *msk,
                msk->pm.extra_subflows++;
                i++;
 
-               if (msk->pm.extra_subflows >= subflows_max)
+               if (msk->pm.extra_subflows >= limit_extra_subflows)
                        break;
        }
        rcu_read_unlock();
@@ -459,13 +460,14 @@ fill_local_addresses_vec_c_flag(struct mptcp_sock *msk,
 {
        unsigned int local_addr_max = mptcp_pm_get_local_addr_max(msk);
        struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk);
-       unsigned int subflows_max = mptcp_pm_get_subflows_max(msk);
        struct sock *sk = (struct sock *)msk;
+       unsigned int limit_extra_subflows;
        struct mptcp_addr_info mpc_addr;
        struct mptcp_pm_local *local;
        int i = 0;
 
        mptcp_local_address((struct sock_common *)msk, &mpc_addr);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        while (msk->pm.local_addr_used < local_addr_max) {
                local = &locals[i];
@@ -486,7 +488,7 @@ fill_local_addresses_vec_c_flag(struct mptcp_sock *msk,
                msk->pm.extra_subflows++;
                i++;
 
-               if (msk->pm.extra_subflows >= subflows_max)
+               if (msk->pm.extra_subflows >= limit_extra_subflows)
                        break;
        }
 
@@ -544,14 +546,14 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
 {
        struct mptcp_pm_local locals[MPTCP_PM_ADDR_MAX];
        struct sock *sk = (struct sock *)msk;
+       unsigned int limit_extra_subflows;
        unsigned int add_addr_accept_max;
        struct mptcp_addr_info remote;
-       unsigned int subflows_max;
        bool sf_created = false;
        int i, nr;
 
        add_addr_accept_max = mptcp_pm_get_add_addr_accept_max(msk);
-       subflows_max = mptcp_pm_get_subflows_max(msk);
+       limit_extra_subflows = mptcp_pm_get_limit_extra_subflows(msk);
 
        pr_debug("accepted %d:%d remote family %d\n",
                 msk->pm.add_addr_accepted, add_addr_accept_max,
@@ -586,7 +588,7 @@ static void mptcp_pm_nl_add_addr_received(struct mptcp_sock *msk)
                if (remote.id)
                        msk->pm.add_addr_accepted++;
                if (msk->pm.add_addr_accepted >= add_addr_accept_max ||
-                   msk->pm.extra_subflows >= subflows_max)
+                   msk->pm.extra_subflows >= limit_extra_subflows)
                        WRITE_ONCE(msk->pm.accept_addr, false);
        }
 }
@@ -1285,13 +1287,13 @@ int mptcp_pm_nl_set_limits_doit(struct sk_buff *skb, struct genl_info *info)
        if (ret)
                goto unlock;
 
-       subflows = pernet->subflows_max;
+       subflows = pernet->limit_extra_subflows;
        ret = parse_limit(info, MPTCP_PM_ATTR_SUBFLOWS, &subflows);
        if (ret)
                goto unlock;
 
        WRITE_ONCE(pernet->add_addr_accept_max, rcv_addrs);
-       WRITE_ONCE(pernet->subflows_max, subflows);
+       WRITE_ONCE(pernet->limit_extra_subflows, subflows);
 
 unlock:
        spin_unlock_bh(&pernet->lock);
@@ -1318,7 +1320,7 @@ int mptcp_pm_nl_get_limits_doit(struct sk_buff *skb, struct genl_info *info)
                goto fail;
 
        if (nla_put_u32(msg, MPTCP_PM_ATTR_SUBFLOWS,
-                       READ_ONCE(pernet->subflows_max)))
+                       READ_ONCE(pernet->limit_extra_subflows)))
                goto fail;
 
        genlmsg_end(msg, reply);
@@ -1427,7 +1429,7 @@ bool mptcp_pm_nl_check_work_pending(struct mptcp_sock *msk)
 {
        struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk);
 
-       if (msk->pm.extra_subflows == mptcp_pm_get_subflows_max(msk) ||
+       if (msk->pm.extra_subflows == mptcp_pm_get_limit_extra_subflows(msk) ||
            (find_next_and_bit(pernet->id_bitmap, msk->pm.id_avail_bitmap,
                               MPTCP_PM_MAX_ADDR_ID + 1, 0) == MPTCP_PM_MAX_ADDR_ID + 1)) {
                WRITE_ONCE(msk->pm.work_pending, false);
@@ -1462,7 +1464,7 @@ static int __net_init pm_nl_init_net(struct net *net)
        INIT_LIST_HEAD_RCU(&pernet->local_addr_list);
 
        /* Cit. 2 subflows ought to be enough for anybody. */
-       pernet->subflows_max = 2;
+       pernet->limit_extra_subflows = 2;
        pernet->next_id = 1;
        pernet->stale_loss_cnt = 4;
        spin_lock_init(&pernet->lock);

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ca68f9a7580149e43139ec6cc61a1e0b966e7a22..4c777f87b0497ed623f0d51bf1f87cfa011cf0eb 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1182,13 +1182,13 @@ void mptcp_pm_worker(struct mptcp_sock *msk);
 void __mptcp_pm_kernel_worker(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_add_addr_signal_max(const struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_add_addr_accept_max(const struct mptcp_sock *msk);
-unsigned int mptcp_pm_get_subflows_max(const struct mptcp_sock *msk);
+unsigned int mptcp_pm_get_limit_extra_subflows(const struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_local_addr_max(const struct mptcp_sock *msk);
 
 /* called under PM lock */
 static inline void __mptcp_pm_close_subflow(struct mptcp_sock *msk)
 {
-       if (--msk->pm.extra_subflows < mptcp_pm_get_subflows_max(msk))
+       if (--msk->pm.extra_subflows < mptcp_pm_get_limit_extra_subflows(msk))
                WRITE_ONCE(msk->pm.accept_subflow, true);
 }
 
@@ -1204,7 +1204,7 @@ static inline bool mptcp_pm_add_addr_c_flag_case(struct mptcp_sock *msk)
        return READ_ONCE(msk->pm.remote_deny_join_id0) &&
               msk->pm.local_addr_used == 0 &&
               mptcp_pm_get_add_addr_accept_max(msk) == 0 &&
-              msk->pm.extra_subflows < mptcp_pm_get_subflows_max(msk);
+              msk->pm.extra_subflows < mptcp_pm_get_limit_extra_subflows(msk);
 }
 
 void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk);

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 17966da80239d731de925f3e4211b3ee00f802e4..4e82bcfcd34e3a1dffb05799cf181ee2940e75d7 100644 (file)
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -972,8 +972,8 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, struct mptcp_info *info)
 
        /* The following limits only make sense for the in-kernel PM */
        if (mptcp_pm_is_kernel(msk)) {
-               info->mptcpi_subflows_max =
-                       mptcp_pm_get_subflows_max(msk);
+               info->mptcpi_limit_extra_subflows =
+                       mptcp_pm_get_limit_extra_subflows(msk);
                info->mptcpi_add_addr_signal_max =
                        mptcp_pm_get_add_addr_signal_max(msk);
                info->mptcpi_add_addr_accepted_max =