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| author | Florian Westphal <fw@strlen.de> | 2020-11-16 12:48:12 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-11-16 21:46:07 +0300 |
| commit | 8edf08649eede6e5a3e39a3d38c63f30039a0c1e (patch) | |
| tree | 278ab97b84769bc057a3f5449aaec7d19019c665 /net/mptcp/subflow.c | |
| parent | 813e0a683d4cacb668622bc9a1693cb82b5f8ff8 (diff) | |
| download | linux-8edf08649eede6e5a3e39a3d38c63f30039a0c1e.tar.xz | |
mptcp: rework poll+nospace handling
MPTCP maintains a status bit, MPTCP_SEND_SPACE, that is set when at
least one subflow and the mptcp socket itself are writeable.
mptcp_poll returns EPOLLOUT if the bit is set.
mptcp_sendmsg makes sure MPTCP_SEND_SPACE gets cleared when last write
has used up all subflows or the mptcp socket wmem.
This reworks nospace handling as follows:
MPTCP_SEND_SPACE is replaced with MPTCP_NOSPACE, i.e. inverted meaning.
This bit is set when the mptcp socket is not writeable.
The mptcp-level ack path schedule will then schedule the mptcp worker
to allow it to free already-acked data (and reduce wmem usage).
This will then wake userspace processes that wait for a POLLOUT event.
sendmsg will set MPTCP_NOSPACE only when it has to wait for more
wmem (blocking I/O case).
poll path will set MPTCP_NOSPACE in case the mptcp socket is
not writeable.
Normal tcp-level notification (SOCK_NOSPACE) is only enabled
in case the subflow socket has no available wmem.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/mptcp/subflow.c')
| -rw-r--r-- | net/mptcp/subflow.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 42581ffb0c7e..794259789194 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -997,17 +997,16 @@ static void subflow_data_ready(struct sock *sk) static void subflow_write_space(struct sock *sk) { struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk); + struct socket *sock = READ_ONCE(sk->sk_socket); struct sock *parent = subflow->conn; if (!sk_stream_is_writeable(sk)) return; - if (sk_stream_is_writeable(parent)) { - set_bit(MPTCP_SEND_SPACE, &mptcp_sk(parent)->flags); - smp_mb__after_atomic(); - /* set SEND_SPACE before sk_stream_write_space clears NOSPACE */ - sk_stream_write_space(parent); - } + if (sock && sk_stream_is_writeable(parent)) + clear_bit(SOCK_NOSPACE, &sock->flags); + + sk_stream_write_space(parent); } static struct inet_connection_sock_af_ops * |