On Mon, Sep 15, 2025 at 11:47 PM [off-list ref] wrote:

From: Xuanqiang Luo <redacted>

After replacing R/W locks with RCU in commit 3ab5aee7fe84 ("net: Convert
TCP & DCCP hash tables to use RCU / hlist_nulls"), a race window emerged
during the switch from reqsk/sk to sk/tw.

Now that both timewait sock (tw) and full sock (sk) reside on the same
ehash chain, it is appropriate to introduce hlist_nulls replace
operations, to eliminate the race conditions caused by this window.

---
Changes:
  v2:
    * Patch 1
        * Use WRITE_ONCE() to initialize old->pprev.
    * Patch 2&3
        * Optimize sk hashed check. Thanks Kuni for pointing it out!

  v1: https://lore.kernel.org/all/20250915070308.111816-1-xuanqiang.luo@linux.dev/ (local)

Note : I think you sent an earlier version, you should have added a
link to the discussion,
and past feedback/suggestions.

Lack of credit is a bit annoying frankly.

I will take a look at your series, thanks.

Xuanqiang Luo (3):
  rculist: Add __hlist_nulls_replace_rcu() and
    hlist_nulls_replace_init_rcu()
  inet: Avoid ehash lookup race in inet_ehash_insert()
  inet: Avoid ehash lookup race in inet_twsk_hashdance_schedule()

 include/linux/rculist_nulls.h | 61 +++++++++++++++++++++++++++++++++++
 include/net/sock.h            | 23 +++++++++++++
 net/ipv4/inet_hashtables.c    |  4 ++-
 net/ipv4/inet_timewait_sock.c | 15 ++++-----
 4 files changed, 93 insertions(+), 10 deletions(-)

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2.25.1