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| author | Paolo Abeni <pabeni@redhat.com> | 2021-08-14 01:15:45 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-08-14 13:37:25 +0300 |
| commit | ff5a0b421cb23bf6b2898939ffef5b683045d9d3 (patch) | |
| tree | c5601da51b264d08d1ce35d14d7a6b051d6786a5 /net/mptcp/pm_netlink.c | |
| parent | 6da14d74e2bd07bca2cba10878dda5dc0485d59c (diff) | |
| download | linux-ff5a0b421cb23bf6b2898939ffef5b683045d9d3.tar.xz | |
mptcp: faster active backup recovery
The msk can use backup subflows to transmit in-sequence data
only if there are no other active subflow. On active backup
scenario, the MPTCP connection can do forward progress only
due to MPTCP retransmissions - rtx can pick backup subflows.
This patch introduces a new flag flow MPTCP subflows: if the
underlying TCP connection made no progresses for long time,
and there are other less problematic subflows available, the
given subflow become stale.
Stale subflows are not considered active: if all non backup
subflows become stale, the MPTCP scheduler can pick backup
subflows for plain transmissions.
Stale subflows can return in active state, as soon as any reply
from the peer is observed.
Active backup scenarios can now leverage the available b/w
with no restrinction.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/207
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mptcp/pm_netlink.c')
| -rw-r--r-- | net/mptcp/pm_netlink.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 56263c2c4014..c0eb14e05bea 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -46,6 +46,7 @@ struct pm_nl_pernet { spinlock_t lock; struct list_head local_addr_list; unsigned int addrs; + unsigned int stale_loss_cnt; unsigned int add_addr_signal_max; unsigned int add_addr_accept_max; unsigned int local_addr_max; @@ -899,6 +900,42 @@ static const struct nla_policy mptcp_pm_policy[MPTCP_PM_ATTR_MAX + 1] = { [MPTCP_PM_ATTR_SUBFLOWS] = { .type = NLA_U32, }, }; +void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk) +{ + struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk); + struct sock *sk = (struct sock *)msk; + unsigned int active_max_loss_cnt; + struct net *net = sock_net(sk); + unsigned int stale_loss_cnt; + bool slow; + + stale_loss_cnt = mptcp_stale_loss_cnt(net); + if (subflow->stale || !stale_loss_cnt || subflow->stale_count <= stale_loss_cnt) + return; + + /* look for another available subflow not in loss state */ + active_max_loss_cnt = max_t(int, stale_loss_cnt - 1, 1); + mptcp_for_each_subflow(msk, iter) { + if (iter != subflow && mptcp_subflow_active(iter) && + iter->stale_count < active_max_loss_cnt) { + /* we have some alternatives, try to mark this subflow as idle ...*/ + slow = lock_sock_fast(ssk); + if (!tcp_rtx_and_write_queues_empty(ssk)) { + subflow->stale = 1; + __mptcp_retransmit_pending_data(sk); + } + unlock_sock_fast(ssk, slow); + + /* always try to push the pending data regarless of re-injections: + * we can possibly use backup subflows now, and subflow selection + * is cheap under the msk socket lock + */ + __mptcp_push_pending(sk, 0); + return; + } + } +} + static int mptcp_pm_family_to_addr(int family) { #if IS_ENABLED(CONFIG_MPTCP_IPV6) @@ -1922,6 +1959,7 @@ static int __net_init pm_nl_init_net(struct net *net) INIT_LIST_HEAD_RCU(&pernet->local_addr_list); pernet->next_id = 1; + pernet->stale_loss_cnt = 4; spin_lock_init(&pernet->lock); /* No need to initialize other pernet fields, the struct is zeroed at |