In addition to tcp autotuning during read, it may also increase the
receive buffer in tcp_clamp_window().
In this case, mptcp should adjust its receive buffer size as well so
it can move all pending skbs from the subflow socket to the mptcp socket.
At this time, TCP can have more skbs ready for processing than what the
mptcp receive buffer size allows.
In the mptcp case, the receive window announced is based on the free
space of the mptcp parent socket instead of the individual subflows.
Following the subflow allows mptcp to grow its receive buffer.
This is especially noticeable for loopback traffic where two skbs are
enough to fill the initial receive window.
In mptcp_data_ready() we do not hold the mptcp socket lock, so modifying
mptcp_sk->sk_rcvbuf is racy. Do it when moving skbs from subflow to
mptcp socket, both sockets are locked in this case.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When moving the skbs from the subflow into the msk receive
queue, we must schedule there the required amount of memory.
Try to borrow the required memory from the subflow, if needed,
so that we leverage the existing TCP heuristic.
Fixes: 6771bfd9ee ("mptcp: update mptcp ack sequence from work queue")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Link: https://lore.kernel.org/r/f6143a6193a083574f11b00dbf7b5ad151bc4ff4.1603810630.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Minor conflicts in net/mptcp/protocol.h and
tools/testing/selftests/net/Makefile.
In both cases code was added on both sides in the same place
so just keep both.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The msk can close MP_JOIN subflows if the initial handshake
fails. Currently such subflows are kept alive in the
conn_list until the msk itself is closed.
Beyond the wasted memory, we could end-up sending the
DATA_FIN and the DATA_FIN ack on such socket, even after a
reset.
Fixes: 43b54c6ee3 ("mptcp: Use full MPTCP-level disconnect state machine")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If recvmsg() and the workqueue race to dequeue the data
pending on some subflow, the current mapping for such
subflow covers several skbs and some of them have not
reached yet the received, either the worker or recvmsg()
can find a subflow with the data_avail flag set - since
the current mapping is valid and in sequence - but no
skbs in the receive queue - since the other entity just
processed them.
The above will lead to an unbounded loop in __mptcp_move_skbs()
and a subsequent hang of any task trying to acquiring the msk
socket lock.
This change addresses the issue stopping the __mptcp_move_skbs()
loop as soon as we detect the above race (empty receive queue
with data_avail set).
Reported-and-tested-by: syzbot+fcf8ca5817d6e92c6567@syzkaller.appspotmail.com
Fixes: ab174ad8ef ("mptcp: move ooo skbs into msk out of order queue.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently we skip calling tcp_cleanup_rbuf() when packets
are moved into the OoO queue or simply dropped. In both
cases we still increment tp->copied_seq, and we should
ask the TCP stack to check for ack.
Fixes: c76c695656 ("mptcp: call tcp_cleanup_rbuf on subflows")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rejecting non-native endian BTF overlapped with the addition
of support for it.
The rest were more simple overlapping changes, except the
renesas ravb binding update, which had to follow a file
move as well as a YAML conversion.
Signed-off-by: David S. Miller <davem@davemloft.net>
The msk->ack_seq value is sometimes read without the msk lock held, so
make proper use of READ_ONCE and WRITE_ONCE.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch added a new helper named mptcp_destroy_common containing the
shared code between mptcp_destroy() and mptcp_sock_destruct().
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implements the remove announced addr and subflow logic in PM
netlink.
When the PM netlink removes an address, we traverse all the existing msk
sockets to find the relevant sockets.
We add a new list named anno_list in mptcp_pm_data, to record all the
announced addrs. In the traversing, we check if it has been recorded.
If it has been, we trigger the RM_ADDR signal.
We also check if this address is in conn_list. If it is, we remove the
subflow which using this local address.
Since we call mptcp_pm_free_anno_list in mptcp_destroy, we need to move
__mptcp_init_sock before the mptcp_is_enabled check in mptcp_init_sock.
Suggested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Suggested-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch added the RM_ADDR option parsing logic:
We parsed the incoming options to find if the rm_addr option is received,
and called mptcp_pm_rm_addr_received to schedule PM work to a new status,
named MPTCP_PM_RM_ADDR_RECEIVED.
PM work got this status, and called mptcp_pm_nl_rm_addr_received to handle
it.
In mptcp_pm_nl_rm_addr_received, we closed the subflow matching the rm_id,
and updated PM counter.
Suggested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Suggested-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fixes coccicheck warnig:
net/mptcp/protocol.c:164:11-18: WARNING: Unsigned expression compared with zero: max_seq > 0
Fixes: ab174ad8ef ("mptcp: move ooo skbs into msk out of order queue")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
That is needed to let the subflows announce promptly when new
space is available in the receive buffer.
tcp_cleanup_rbuf() is currently a static function, drop the
scope modifier and add a declaration in the TCP header.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Update the scheduler to less trivial heuristic: cache
the last used subflow, and try to send on it a reasonably
long burst of data.
When the burst or the subflow send space is exhausted, pick
the subflow with the lower ratio between write space and
send buffer - that is, the subflow with the greater relative
amount of free space.
v1 -> v2:
- fix 32 bit build breakage due to 64bits div
- fix checkpath issues (uint64_t -> u64)
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a bunch of MPTCP mibs related to MPTCP OoO data
processing.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add an RB-tree to cope with OoO (at MPTCP level) data.
__mptcp_move_skb() insert into the RB tree "future"
data, eventually coalescing skb as allowed by the
MPTCP DSN.
To simplify sequence accounting, move the DSN inside
the cb.
After successfully enqueuing in sequence data, check
if we can use any data from the RB tree.
Additionally move the data_fin check after spooling
data from the OoO tree, otherwise we could miss shutdown
events.
The RB tree code is copied as verbatim as possible
from tcp_data_queue_ofo(), with a few simplifications
due to the fact that MPTCP doesn't need to cope with
sacks. All bugs here are added by me.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Factor-out existing code, will be re-used by the
next patch.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Let the msk sendbuf track the size of the larger subflow's
send window, so that we ensure mptcp_sendmsg() does not
exceed MPTCP-level send window.
The update is performed just before try to send any data.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a prerequisite to allow receiving data from multiple
subflows without re-injection.
Instead of dropping the OoO - "future" data in
subflow_check_data_avail(), call into __mptcp_move_skbs()
and let the msk drop that.
To avoid code duplication factor out the mptcp_subflow_discard_data()
helper.
Note that __mptcp_move_skbs() can now find multiple subflows
with data avail (comprising to-be-discarded data), so must
update the byte counter incrementally.
v1 -> v2:
- fix checkpatch issues (unsigned -> unsigned int)
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, when checking for the 'msk is writable' condition, we
look at the individual subflows write space.
That works well while we send data via a single subflow, but will
not as soon as we will enable concurrent xmit on multiple subflows.
With this change msk becomes writable when the following conditions
hold:
- the socket has some free write space
- there is at least a subflow with write free space
Additionally we need to set the NOSPACE bit on all subflows
before blocking.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We got slightly different patches removing a double word
in a comment in net/ipv4/raw.c - picked the version from net.
Simple conflict in drivers/net/ethernet/ibm/ibmvnic.c. Use cached
values instead of VNIC login response buffer (following what
commit 507ebe6444 ("ibmvnic: Fix use-after-free of VNIC login
response buffer") did).
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pull networking fixes from David Miller:
1) Use netif_rx_ni() when necessary in batman-adv stack, from Jussi
Kivilinna.
2) Fix loss of RTT samples in rxrpc, from David Howells.
3) Memory leak in hns_nic_dev_probe(), from Dignhao Liu.
4) ravb module cannot be unloaded, fix from Yuusuke Ashizuka.
5) We disable BH for too lokng in sctp_get_port_local(), add a
cond_resched() here as well, from Xin Long.
6) Fix memory leak in st95hf_in_send_cmd, from Dinghao Liu.
7) Out of bound access in bpf_raw_tp_link_fill_link_info(), from
Yonghong Song.
8) Missing of_node_put() in mt7530 DSA driver, from Sumera
Priyadarsini.
9) Fix crash in bnxt_fw_reset_task(), from Michael Chan.
10) Fix geneve tunnel checksumming bug in hns3, from Yi Li.
11) Memory leak in rxkad_verify_response, from Dinghao Liu.
12) In tipc, don't use smp_processor_id() in preemptible context. From
Tuong Lien.
13) Fix signedness issue in mlx4 memory allocation, from Shung-Hsi Yu.
14) Missing clk_disable_prepare() in gemini driver, from Dan Carpenter.
15) Fix ABI mismatch between driver and firmware in nfp, from Louis
Peens.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (110 commits)
net/smc: fix sock refcounting in case of termination
net/smc: reset sndbuf_desc if freed
net/smc: set rx_off for SMCR explicitly
net/smc: fix toleration of fake add_link messages
tg3: Fix soft lockup when tg3_reset_task() fails.
doc: net: dsa: Fix typo in config code sample
net: dp83867: Fix WoL SecureOn password
nfp: flower: fix ABI mismatch between driver and firmware
tipc: fix shutdown() of connectionless socket
ipv6: Fix sysctl max for fib_multipath_hash_policy
drivers/net/wan/hdlc: Change the default of hard_header_len to 0
net: gemini: Fix another missing clk_disable_unprepare() in probe
net: bcmgenet: fix mask check in bcmgenet_validate_flow()
amd-xgbe: Add support for new port mode
net: usb: dm9601: Add USB ID of Keenetic Plus DSL
vhost: fix typo in error message
net: ethernet: mlx4: Fix memory allocation in mlx4_buddy_init()
pktgen: fix error message with wrong function name
net: ethernet: ti: am65-cpsw: fix rmii 100Mbit link mode
cxgb4: fix thermal zone device registration
...
After subflow lock is dropped, more wmem might have been made available.
This fixes a deadlock in mptcp_connect.sh 'mmap' mode: wmem is exhausted.
But as the mptcp socket holds on to already-acked data (for retransmit)
no wakeup will occur.
Using 'goto restart' calls mptcp_clean_una(sk) which will free pages
that have been acked completely in the mean time.
Fixes: fb529e62d3 ("mptcp: break and restart in case mptcp sndbuf is full")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fix wasn't correct: When this function is invoked from the
retransmission worker, the iterator contains garbage and resetting
it causes a crash.
As the work queue should not be performance critical also zero the
msghdr struct.
Fixes: 3575938313 "(mptcp: sendmsg: reset iter on error)"
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Once we've copied data from the iterator we need to revert in case we
end up not sending any data.
This bug doesn't trigger with normal 'poll' based tests, because
we only feed a small chunk of data to kernel after poll indicated
POLLOUT. With blocking IO and large writes this triggers. Receiver
ends up with less data than it should get.
Fixes: 72511aab95 ("mptcp: avoid blocking in tcp_sendpages")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In case of memory pressure, mptcp_sendmsg() may call
sk_stream_wait_memory() after succesfully xmitting some
bytes. If the latter fails we currently return to the
user-space the error code, ignoring the succeful xmit.
Address the issue always checking for the xmitted bytes
before mptcp_sendmsg() completes.
Fixes: f296234c98 ("mptcp: Add handling of incoming MP_JOIN requests")
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use mptcp_for_each_subflow in mptcp_stream_accept instead of
open-coding.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The MPTCP socket's write_seq member can be read without the msk lock
held, so use WRITE_ONCE() to store it.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The MPTCP socket's write_seq member should be read with READ_ONCE() when
the msk lock is not held.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
RFC 8684 appendix D describes the connection state machine for
MPTCP. This patch implements the DATA_FIN / DATA_ACK exchanges and
MPTCP-level socket state changes described in that appendix, rather than
simply sending DATA_FIN along with TCP FIN when disconnecting subflows.
DATA_FIN is now sent and acknowledged before shutting down the
subflows. Received DATA_FIN information (if not part of a data packet)
is written to the MPTCP socket when the incoming DSS option is parsed by
the subflow, and the MPTCP worker is scheduled to process the
flag. DATA_FIN received as part of a full DSS mapping will be handled
when the mapping is processed.
The DATA_FIN is acknowledged by the worker if the reader is caught
up. If there is still data to be moved to the MPTCP-level queue, ack_seq
will be incremented to account for the DATA_FIN when it reaches the end
of the stream and a DATA_ACK will be sent to the peer.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
After DATA_FIN has been sent, the peer will acknowledge it. An ack of
the relevant MPTCP-level sequence number will update the MPTCP
connection state appropriately.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This will be used to transition to the appropriate state on close and
determine if a DATA_FIN needs to be sent for that state transition.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Incoming DATA_FIN headers need to propagate the presence of the DATA_FIN
bit and the associated sequence number to the MPTCP layer, even when
arriving on a bare ACK that does not get added to the receive queue. Add
structure members to store the DATA_FIN information and helpers to set
and check those values.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since DATA_FIN information is the same for every subflow, store it only
in the mptcp_sock.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
mptcp_close() acquires the msk lock, so it clearly should not be held
before the function is called.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A MPTCP socket where sending has been shut down should not attempt to
send additional data, since DATA_FIN has already been sent.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Unblocking sockets used for outgoing connections were not containing
inet info about the initial connection due to a typo there: the value of
"err" variable is negative in the kernelspace.
This fixes the creation of additional subflows where the remote port has
to be reused if the other host didn't announce another one. This also
fixes inet_diag showing blank info about MPTCP sockets from unblocking
sockets doing a connect().
Fixes: 41be81a8d3 ("mptcp: fix unblocking connect()")
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer. This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pass a sockptr_t to prepare for set_fs-less handling of the kernel
pointer from bpf-cgroup.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently accepted msk sockets become established only after
accept() returns the new sk to user-space.
As MP_JOIN request are refused as per RFC spec on non fully
established socket, the above causes mp_join self-tests
instabilities.
This change lets the msk entering the established status
as soon as it receives the 3rd ack and propagates the first
subflow fully established status on the msk socket.
Finally we can change the subflow acceptance condition to
take in account both the sock state and the msk fully
established flag.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the unlikely event of a failure at connect time,
we currently clear the request_mptcp flag - so that
the MPC handshake is not started at all, but the msk
is not explicitly marked as fallback.
This would lead to later insertion of wrong DSS options
in the xmitted packets, in violation of RFC specs and
possibly fooling the peer.
Fixes: e1ff9e82e2 ("net: mptcp: improve fallback to TCP")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When updating a partially acked data fragment, we
actually corrupt it. This is irrelevant till we send
data on a single subflow, as retransmitted data, if
any are discarded by the peer as duplicate, but it
will cause data corruption as soon as we will start
creating non backup subflows.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently we do not init the subflow write sequence for
MP_JOIN subflows. This will cause bad mapping being
generated as soon as we will use non backup subflow.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add the compat handling to sock_common_{get,set}sockopt instead,
keyed of in_compat_syscall(). This allow to remove the now unused
->compat_{get,set}sockopt methods from struct proto_ops.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
We can re-use the existing work queue to handle path management
instead of a dedicated work queue. Just move pm_worker to protocol.c,
call it from the mptcp worker and get rid of the msk lock (already held).
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Without this, Opensshd fails to open an ipv6 socket listening
socket:
error: setsockopt IPV6_V6ONLY: Operation not supported
error: Bind to port 22 on :: failed: Address already in use.
Opensshd opens an ipv4 and and ipv6 listening socket, but because
IPV6_V6ONLY setsockopt fails, the port number is already in use.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This will e.g. make 'sshd restart' work when MPTCP is used, as we will
now set this option on the listener socket instead of only the mptcp
socket (where it has no effect).
We still need to copy the setting to the master socket so that a
subsequent getsockopt() returns the expected value.
Reported-by: Christoph Paasch <cpaasch@apple.com>
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
