[PATCH mptcp-net 0/2] mptcp: replace lock_sock_fast with sleepable lock

[Gang Yan <gang.yan@linux.dev>]

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From: Gang Yan <yangang@kylinos.cn>

Hi Matt,

I make some progress about the issue sashiko mentioned in:
https://sashiko.dev/#/patchset/20260420093343.16443-1-gang.yan@linux.dev

The problem does exist,though the trigger conditions seem quite strict.

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I’ve checked how TCP and core socket handle similar sockopt operations,
and found they almost always use sockopt_lock_sock() in 
setsockopt/getsockopt paths — a variant of lock_sock() that also
considers BPF cases.

I think we can align MPTCP with a similar approach to fix this properly.
This will come as a two-patch series, split for easier review and
backporting to stable branches:

    - 0001: The first patch replaces lock_sock_fast() with lock_sock()
      to fix the potential sleeping issue in timestamp and timestamping
      sockopt handlers.

    - 0002: The second patch converts all lock operations in MPTCP
      setsockopt / getsockopt to use sockopt_lock_sock(), preventing
      similar issues from being accidentally introduced in the future.
      And I think it should use 'mptcp-next' tag.

Gang Yan (2):
  mptcp: fix scheduling with atomic in timestamp sockopt
  mptcp: use sockopt_lock(release)_sock in sockopt

 net/mptcp/sockopt.c | 121 ++++++++++++++++++++++----------------------
 1 file changed, 60 insertions(+), 61 deletions(-)

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2.43.0