mptcp: pr_debug: add missing \n at the end

pr_debug() have been added in various places in MPTCP code to help
developers to debug some situations. With the dynamic debug feature, it
is easy to enabl

mptcp: pr_debug: add missing \n at the end

pr_debug() have been added in various places in MPTCP code to help
developers to debug some situations. With the dynamic debug feature, it
is easy to enable all or some of them, and asks users to reproduce
issues with extra debug.

Many of these pr_debug() don't end with a new line, while no 'pr_cont()'
are used in MPTCP code. So the goal was not to display multiple debug
messages on one line: they were then not missing the '\n' on purpose.
Not having the new line at the end causes these messages to be printed
with a delay, when something else needs to be printed. This issue is not
visible when many messages need to be printed, but it is annoying and
confusing when only specific messages are expected, e.g.

# echo "func mptcp_pm_add_addr_echoed +fmp" \
> /sys/kernel/debug/dynamic_debug/control
# ./mptcp_join.sh "signal address"; \
echo "$(awk '{print $1}' /proc/uptime) - end"; \
sleep 5s; \
echo "$(awk '{print $1}' /proc/uptime) - restart"; \
./mptcp_join.sh "signal address"
013 signal address
(...)
10.75 - end
15.76 - restart
013 signal address
[ 10.367935] mptcp:mptcp_pm_add_addr_echoed: MPTCP: msk=(...)
(...)

=> a delay of 5 seconds: printed with a 10.36 ts, but after 'restart'
which was printed at the 15.76 ts.

The 'Fixes' tag here below points to the first pr_debug() used without
'\n' in net/mptcp. This patch could be split in many small ones, with
different Fixes tag, but it doesn't seem worth it, because it is easy to
re-generate this patch with this simple 'sed' command:

git grep -l pr_debug -- net/mptcp |
xargs sed -i "s/\(pr_debug(\".*[^n]\)\(\"[,)]\)/\1\\\n\2/g"

So in case of conflicts, simply drop the modifications, and launch this
command.

Fixes: f870fa0b5768 ("mptcp: Add MPTCP socket stubs")
Cc: stable@vger.kernel.org
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240826-net-mptcp-close-extra-sf-fin-v1-4-905199fe1172@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: fully established after ADD_ADDR echo on MPJ

Before this patch, receiving an ADD_ADDR echo on the just connected
MP_JOIN subflow -- initiator side, after the MP_JOIN 3WHS -- was
resulting in

mptcp: fully established after ADD_ADDR echo on MPJ

Before this patch, receiving an ADD_ADDR echo on the just connected
MP_JOIN subflow -- initiator side, after the MP_JOIN 3WHS -- was
resulting in an MP_RESET. That's because only ACKs with a DSS or
ADD_ADDRs without the echo bit were allowed.

Not allowing the ADD_ADDR echo after an MP_CAPABLE 3WHS makes sense, as
we are not supposed to send an ADD_ADDR before because it requires to be
in full established mode first. For the MP_JOIN 3WHS, that's different:
the ADD_ADDR can be sent on a previous subflow, and the ADD_ADDR echo
can be received on the recently created one. The other peer will already
be in fully established, so it is allowed to send that.

We can then relax the conditions here to accept the ADD_ADDR echo for
MPJ subflows.

Fixes: 67b12f792d5e ("mptcp: full fully established support after ADD_ADDR")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240731-upstream-net-20240731-mptcp-endp-subflow-signal-v1-1-c8a9b036493b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: distinguish rcv vs sent backup flag in requests

When sending an MP_JOIN + SYN + ACK, it is possible to mark the subflow
as 'backup' by setting the flag with the same name. Before this patch,

mptcp: distinguish rcv vs sent backup flag in requests

When sending an MP_JOIN + SYN + ACK, it is possible to mark the subflow
as 'backup' by setting the flag with the same name. Before this patch,
the backup was set if the other peer set it in its MP_JOIN + SYN
request.

It is not correct: the backup flag should be set in the MPJ+SYN+ACK only
if the host asks for it, and not mirroring what was done by the other
peer. It is then required to have a dedicated bit for each direction,
similar to what is done in the subflow context.

Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

show more ...

mptcp: add last time fields in mptcp_info

This patch adds "last time" fields last_data_sent, last_data_recv and
last_ack_recv in struct mptcp_sock to record the last time data_sent,
data_recv and ac

mptcp: add last time fields in mptcp_info

This patch adds "last time" fields last_data_sent, last_data_recv and
last_ack_recv in struct mptcp_sock to record the last time data_sent,
data_recv and ack_recv happened. They all are initialized as
tcp_jiffies32 in __mptcp_init_sock(), and updated as tcp_jiffies32 too
when data is sent in __subflow_push_pending(), data is received in
__mptcp_move_skbs_from_subflow(), and ack is received in ack_update_msk().

Similar to tcpi_last_data_sent, tcpi_last_data_recv and tcpi_last_ack_recv
exposed with TCP, this patch exposes the last time "an action happened" for
MPTCP in mptcp_info, named mptcpi_last_data_sent, mptcpi_last_data_recv and
mptcpi_last_ack_recv, calculated in mptcp_diag_fill_info() as the time
deltas between now and the newly added last time fields in mptcp_sock.

Since msk->last_ack_recv needs to be protected by mptcp_data_lock/unlock,
and lock_sock_fast can sleep and be quite slow, move the entire
mptcp_data_lock/unlock block after the lock/unlock_sock_fast block.
Then mptcpi_last_data_sent and mptcpi_last_data_recv are set in
lock/unlock_sock_fast block, while mptcpi_last_ack_recv is set in
mptcp_data_lock/unlock block, which is protected by a spinlock and
should not block for too long.

Also add three reserved bytes in struct mptcp_info not to have holes in
this structure exposed to userspace.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/446
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240410-upstream-net-next-20240405-mptcp-last-time-info-v2-1-f95bd6b33e51@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: avoid printing warning once on client side

After the 'Fixes' commit mentioned below, the client side might print
the following warning once when a subflow is fully established at the
receptio

mptcp: avoid printing warning once on client side

After the 'Fixes' commit mentioned below, the client side might print
the following warning once when a subflow is fully established at the
reception of any valid additional ack:

MPTCP: bogus mpc option on established client sk

That's a normal situation, and no warning should be printed for that. We
can then skip the check when the label is used.

Fixes: e4a0fa47e816 ("mptcp: corner case locking for rx path fields initialization")
Cc: stable@vger.kernel.org
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240223-upstream-net-20240223-misc-fixes-v1-3-162e87e48497@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: corner case locking for rx path fields initialization

Most MPTCP-level related fields are under the mptcp data lock
protection, but are written one-off without such lock at MPC
complete time,

mptcp: corner case locking for rx path fields initialization

Most MPTCP-level related fields are under the mptcp data lock
protection, but are written one-off without such lock at MPC
complete time, both for the client and the server

Leverage the mptcp_propagate_state() infrastructure to move such
initialization under the proper lock client-wise.

The server side critical init steps are done by
mptcp_subflow_fully_established(): ensure the caller properly held the
relevant lock, and avoid acquiring the same lock in the nested scopes.

There are no real potential races, as write access to such fields
is implicitly serialized by the MPTCP state machine; the primary
goal is consistency.

Fixes: d22f4988ffec ("mptcp: process MP_CAPABLE data option")
Cc: stable@vger.kernel.org
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>

show more ...

mptcp: annotate lockless access for RX path fields

The following fields:

- ack_seq
- snd_una
- wnd_end
- rmem_fwd_alloc

are protected by the data lock end accessed lockless in a few
spots. Ens

mptcp: annotate lockless access for RX path fields

The following fields:

- ack_seq
- snd_una
- wnd_end
- rmem_fwd_alloc

are protected by the data lock end accessed lockless in a few
spots. Ensure ONCE annotation for write (under such lock) and for
lockless read.

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>

show more ...

mptcp: annotate lockless access for the tx path

The mptcp-level TX path info (write_seq, bytes_sent, snd_nxt) are under
the msk socket lock protection, and are accessed lockless in a few spots.

Alw

mptcp: annotate lockless access for the tx path

The mptcp-level TX path info (write_seq, bytes_sent, snd_nxt) are under
the msk socket lock protection, and are accessed lockless in a few spots.

Always mark the write operations with WRITE_ONCE, read operations
outside the lock with READ_ONCE and drop the annotation for read
under such lock.

To simplify the annotations move mptcp_pending_data_fin_ack() from
__mptcp_data_acked() to __mptcp_clean_una(), under the msk socket
lock, where such call would belong.

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>

show more ...

mptcp: annotate access for msk keys

Both the local and the remote key follow the same locking
schema, put in place the proper ONCE accessors.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed

mptcp: annotate access for msk keys

Both the local and the remote key follow the same locking
schema, put in place the proper ONCE accessors.

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>

show more ...

mptcp: mptcp_parse_option() fix for MPTCPOPT_MP_JOIN

mptcp_parse_option() currently sets OPTIONS_MPTCP_MPJ, for the three
possible cases handled for MPTCPOPT_MP_JOIN option.

OPTIONS_MPTCP_MPJ is th

mptcp: mptcp_parse_option() fix for MPTCPOPT_MP_JOIN

mptcp_parse_option() currently sets OPTIONS_MPTCP_MPJ, for the three
possible cases handled for MPTCPOPT_MP_JOIN option.

OPTIONS_MPTCP_MPJ is the combination of three flags:
- OPTION_MPTCP_MPJ_SYN
- OPTION_MPTCP_MPJ_SYNACK
- OPTION_MPTCP_MPJ_ACK

This is a problem, because backup, join_id, token, nonce and/or hmac fields
could be left uninitialized in some cases.

Distinguish the three cases, as following patches will need this step.

Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Peter Krystad <peter.krystad@linux.intel.com>
Cc: Matthieu Baerts <matttbe@kernel.org>
Cc: Mat Martineau <martineau@kernel.org>
Cc: Geliang Tang <geliang.tang@linux.dev>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20240111194917.4044654-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: fix uninit-value in mptcp_incoming_options

Added initialization use_ack to mptcp_parse_option().

Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
Signed-off-by: Edward Adam

mptcp: fix uninit-value in mptcp_incoming_options

Added initialization use_ack to mptcp_parse_option().

Reported-by: syzbot+b834a6b2decad004cfa1@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: fix bogus receive window shrinkage with multiple subflows

In case multiple subflows race to update the mptcp-level receive
window, the subflow losing the race should use the window value
prov

mptcp: fix bogus receive window shrinkage with multiple subflows

In case multiple subflows race to update the mptcp-level receive
window, the subflow losing the race should use the window value
provided by the "winning" subflow to update it's own tcp-level
rcv_wnd.

To such goal, the current code bogusly uses the mptcp-level rcv_wnd
value as observed before the update attempt. On unlucky circumstances
that may lead to TCP-level window shrinkage, and stall the other end.

Address the issue feeding to the rcv wnd update the correct value.

Fixes: f3589be0c420 ("mptcp: never shrink offered window")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/427
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: track some aggregate data counters

Currently there are no data transfer counters accounting for all
the subflows used by a given MPTCP socket. The user-space can compute
such figures aggregat

mptcp: track some aggregate data counters

Currently there are no data transfer counters accounting for all
the subflows used by a given MPTCP socket. The user-space can compute
such figures aggregating the subflow info, but that is inaccurate
if any subflow is closed before the MPTCP socket itself.

Add the new counters in the MPTCP socket itself and expose them
via the existing diag and sockopt. While touching mptcp_diag_fill_info(),
acquire the relevant locks before fetching the msk data, to ensure
better data consistency

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/385
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: move snd_una update earlier for fallback socket

That will avoid an unneeded conditional in both the fast-path
and in the fallback case and will simplify a bit the next
patch.

Signed-off-by:

mptcp: move snd_una update earlier for fallback socket

That will avoid an unneeded conditional in both the fast-path
and in the fallback case and will simplify a bit the next
patch.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: introduces more address related mibs

Currently we don't track explicitly a few events related to address
management suboption handling; this patch adds new mibs for ADD_ADDR
and RM_ADDR optio

mptcp: introduces more address related mibs

Currently we don't track explicitly a few events related to address
management suboption handling; this patch adds new mibs for ADD_ADDR
and RM_ADDR options tx and for missed tx events due to internal storage
exhaustion.

The self-tests must be updated to properly handle different mibs with
the same/shared prefix.

Additionally removes a couple of warning tracking the loss event.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/378
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: remove unused 'remaining' variable

In some functions, 'remaining' variable was given in argument and/or set
but never read.

net/mptcp/options.c:779:3: warning: Value stored to 'remaining'

mptcp: remove unused 'remaining' variable

In some functions, 'remaining' variable was given in argument and/or set
but never read.

net/mptcp/options.c:779:3: warning: Value stored to 'remaining' is never
read [clang-analyzer-deadcode.DeadStores].

net/mptcp/options.c:547:3: warning: Value stored to 'remaining' is never
read [clang-analyzer-deadcode.DeadStores].

The issue has been reported internally by Alibaba CI.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Suggested-by: Mat Martineau <martineau@kernel.org>
Co-developed-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: drop unneeded argument

After commit 3a236aef280e ("mptcp: refactor passive socket initialization"),
every mptcp_pm_fully_established() call is always invoked with a
GFP_ATOMIC argument. We ca

mptcp: drop unneeded argument

After commit 3a236aef280e ("mptcp: refactor passive socket initialization"),
every mptcp_pm_fully_established() call is always invoked with a
GFP_ATOMIC argument. We can then drop it.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: use mptcp_schedule_work instead of open-coding it

Beyond reducing code duplication this also avoids scheduling
the mptcp_worker on a closed socket on some edge scenarios.

The addressed issue

mptcp: use mptcp_schedule_work instead of open-coding it

Beyond reducing code duplication this also avoids scheduling
the mptcp_worker on a closed socket on some edge scenarios.

The addressed issue is actually older than the blamed commit
below, but this fix needs it as a pre-requisite.

Fixes: ba8f48f7a4d7 ("mptcp: introduce mptcp_schedule_work")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: use local variable ssk in write_options

The local variable 'ssk' has been defined at the beginning of the function
mptcp_write_options(), use it instead of getting 'ssk' again.

Reviewed-by:

mptcp: use local variable ssk in write_options

The local variable 'ssk' has been defined at the beginning of the function
mptcp_write_options(), use it instead of getting 'ssk' again.

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: implement delayed seq generation for passive fastopen

With fastopen in place, the first subflow socket is created before the
MPC handshake completes, and we need to properly initialize the se

mptcp: implement delayed seq generation for passive fastopen

With fastopen in place, the first subflow socket is created before the
MPC handshake completes, and we need to properly initialize the sequence
numbers at MPC ACK reception.

Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Dmytro Shytyi <dmytro@shytyi.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: consolidate initial ack seq generation

Currently the initial ack sequence is generated on demand whenever
it's requested and the remote key is handy. The relevant code is
scattered in differe

mptcp: consolidate initial ack seq generation

Currently the initial ack sequence is generated on demand whenever
it's requested and the remote key is handy. The relevant code is
scattered in different places and can lead to multiple, unneeded,
crypto operations.

This change consolidates the ack sequence generation code in a single
helper, storing the sequence number at the subflow level.

The above additionally saves a few conditional in fast-path and will
simplify the upcoming fast-open implementation.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

mptcp: track accurately the incoming MPC suboption type

Currently in the receive path we don't need to discriminate
between MPC SYN, MPC SYN-ACK and MPC ACK, but soon the fastopen
code will need tha

mptcp: track accurately the incoming MPC suboption type

Currently in the receive path we don't need to discriminate
between MPC SYN, MPC SYN-ACK and MPC ACK, but soon the fastopen
code will need that info to properly track the fully established
status.

Track the exact MPC suboption type into the receive opt bitmap.
No functional change intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

tcp: Fix data-races around sysctl_tcp_workaround_signed_windows.

While reading sysctl_tcp_workaround_signed_windows, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.

tcp: Fix data-races around sysctl_tcp_workaround_signed_windows.

While reading sysctl_tcp_workaround_signed_windows, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.

Fixes: 15d99e02baba ("[TCP]: sysctl to allow TCP window > 32767 sans wscale")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

mptcp: Avoid acquiring PM lock for subflow priority changes

The in-kernel path manager code for changing subflow flags acquired both
the msk socket lock and the PM lock when possibly changing the "b

mptcp: Avoid acquiring PM lock for subflow priority changes

The in-kernel path manager code for changing subflow flags acquired both
the msk socket lock and the PM lock when possibly changing the "backup"
and "fullmesh" flags. mptcp_pm_nl_mp_prio_send_ack() does not access
anything protected by the PM lock, and it must release and reacquire
the PM lock.

By pushing the PM lock to where it is needed in mptcp_pm_nl_fullmesh(),
the lock is only acquired when the fullmesh flag is changed and the
backup flag code no longer has to release and reacquire the PM lock. The
change in locking context requires the MIB update to be modified - move
that to a better location instead.

This change also makes it possible to call
mptcp_pm_nl_mp_prio_send_ack() for the userspace PM commands without
manipulating the in-kernel PM lock.

Fixes: 0f9f696a502e ("mptcp: add set_flags command in PM netlink")
Acked-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>

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mptcp: fix shutdown vs fallback race

If the MPTCP socket shutdown happens before a fallback
to TCP, and all the pending data have been already spooled,
we never close the TCP connection.

Address th

mptcp: fix shutdown vs fallback race

If the MPTCP socket shutdown happens before a fallback
to TCP, and all the pending data have been already spooled,
we never close the TCP connection.

Address the issue explicitly checking for critical condition
at fallback time.

Fixes: 1e39e5a32ad7 ("mptcp: infinite mapping sending")
Fixes: 0348c690ed37 ("mptcp: add the fallback check")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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