6.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paolo Abeni pabeni@redhat.com
[ Upstream commit 29b5e5ef87397963ca38d3eec0d296ad1c979bbc ]
Add support for such socket option storing the user-space provided value in a new msk field, and using such data to implement the _mptcp_stream_memory_free() helper, similar to the TCP one.
To avoid adding more indirect calls in the fast path, open-code a variant of sk_stream_memory_free() in mptcp_sendmsg() and add direct calls to the mptcp stream memory free helper where possible.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/464 Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: bd11dc4fb969 ("mptcp: fix full TCP keep-alive support") Signed-off-by: Sasha Levin sashal@kernel.org --- net/mptcp/protocol.c | 39 ++++++++++++++++++++++++++++++++++----- net/mptcp/protocol.h | 28 +++++++++++++++++++++++++++- net/mptcp/sockopt.c | 12 ++++++++++++ 3 files changed, 73 insertions(+), 6 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index fcd85adc621c1..54e29ab911f0d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1757,6 +1757,30 @@ static int do_copy_data_nocache(struct sock *sk, int copy, return 0; }
+/* open-code sk_stream_memory_free() plus sent limit computation to + * avoid indirect calls in fast-path. + * Called under the msk socket lock, so we can avoid a bunch of ONCE + * annotations. + */ +static u32 mptcp_send_limit(const struct sock *sk) +{ + const struct mptcp_sock *msk = mptcp_sk(sk); + u32 limit, not_sent; + + if (sk->sk_wmem_queued >= READ_ONCE(sk->sk_sndbuf)) + return 0; + + limit = mptcp_notsent_lowat(sk); + if (limit == UINT_MAX) + return UINT_MAX; + + not_sent = msk->write_seq - msk->snd_nxt; + if (not_sent >= limit) + return 0; + + return limit - not_sent; +} + static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) { struct mptcp_sock *msk = mptcp_sk(sk); @@ -1801,6 +1825,12 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) struct mptcp_data_frag *dfrag; bool dfrag_collapsed; size_t psize, offset; + u32 copy_limit; + + /* ensure fitting the notsent_lowat() constraint */ + copy_limit = mptcp_send_limit(sk); + if (!copy_limit) + goto wait_for_memory;
/* reuse tail pfrag, if possible, or carve a new one from the * page allocator @@ -1808,9 +1838,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) dfrag = mptcp_pending_tail(sk); dfrag_collapsed = mptcp_frag_can_collapse_to(msk, pfrag, dfrag); if (!dfrag_collapsed) { - if (!sk_stream_memory_free(sk)) - goto wait_for_memory; - if (!mptcp_page_frag_refill(sk, pfrag)) goto wait_for_memory;
@@ -1825,6 +1852,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) offset = dfrag->offset + dfrag->data_len; psize = pfrag->size - offset; psize = min_t(size_t, psize, msg_data_left(msg)); + psize = min_t(size_t, psize, copy_limit); total_ts = psize + frag_truesize;
if (!sk_wmem_schedule(sk, total_ts)) @@ -3761,6 +3789,7 @@ static struct proto mptcp_prot = { .unhash = mptcp_unhash, .get_port = mptcp_get_port, .forward_alloc_get = mptcp_forward_alloc_get, + .stream_memory_free = mptcp_stream_memory_free, .sockets_allocated = &mptcp_sockets_allocated,
.memory_allocated = &tcp_memory_allocated, @@ -3932,12 +3961,12 @@ static __poll_t mptcp_check_writeable(struct mptcp_sock *msk) { struct sock *sk = (struct sock *)msk;
- if (sk_stream_is_writeable(sk)) + if (__mptcp_stream_is_writeable(sk, 1)) return EPOLLOUT | EPOLLWRNORM;
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); smp_mb__after_atomic(); /* NOSPACE is changed by mptcp_write_space() */ - if (sk_stream_is_writeable(sk)) + if (__mptcp_stream_is_writeable(sk, 1)) return EPOLLOUT | EPOLLWRNORM;
return 0; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 6b83869ef7938..2f17f295d7c8b 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -305,6 +305,7 @@ struct mptcp_sock { in_accept_queue:1, free_first:1, rcvspace_init:1; + u32 notsent_lowat; struct work_struct work; struct sk_buff *ooo_last_skb; struct rb_root out_of_order_queue; @@ -789,11 +790,36 @@ static inline bool mptcp_data_fin_enabled(const struct mptcp_sock *msk) READ_ONCE(msk->write_seq) == READ_ONCE(msk->snd_nxt); }
+static inline u32 mptcp_notsent_lowat(const struct sock *sk) +{ + struct net *net = sock_net(sk); + u32 val; + + val = READ_ONCE(mptcp_sk(sk)->notsent_lowat); + return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat); +} + +static inline bool mptcp_stream_memory_free(const struct sock *sk, int wake) +{ + const struct mptcp_sock *msk = mptcp_sk(sk); + u32 notsent_bytes; + + notsent_bytes = READ_ONCE(msk->write_seq) - READ_ONCE(msk->snd_nxt); + return (notsent_bytes << wake) < mptcp_notsent_lowat(sk); +} + +static inline bool __mptcp_stream_is_writeable(const struct sock *sk, int wake) +{ + return mptcp_stream_memory_free(sk, wake) && + __sk_stream_is_writeable(sk, wake); +} + static inline void mptcp_write_space(struct sock *sk) { /* pairs with memory barrier in mptcp_poll */ smp_mb(); - sk_stream_write_space(sk); + if (mptcp_stream_memory_free(sk, 1)) + sk_stream_write_space(sk); }
static inline void __mptcp_sync_sndbuf(struct sock *sk) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 82d0cd0819f09..f2fe28a3912a9 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -810,6 +810,16 @@ static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname, return 0; case TCP_ULP: return -EOPNOTSUPP; + case TCP_NOTSENT_LOWAT: + ret = mptcp_get_int_option(msk, optval, optlen, &val); + if (ret) + return ret; + + lock_sock(sk); + WRITE_ONCE(msk->notsent_lowat, val); + mptcp_write_space(sk); + release_sock(sk); + return 0; case TCP_CONGESTION: return mptcp_setsockopt_sol_tcp_congestion(msk, optval, optlen); case TCP_CORK: @@ -1343,6 +1353,8 @@ static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname, return mptcp_put_int_option(msk, optval, optlen, msk->cork); case TCP_NODELAY: return mptcp_put_int_option(msk, optval, optlen, msk->nodelay); + case TCP_NOTSENT_LOWAT: + return mptcp_put_int_option(msk, optval, optlen, msk->notsent_lowat); } return -EOPNOTSUPP; }