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From: Ankit Jain <ankit-aj.jain@broadcom.com>
To: kuba@kernel.org
Cc: netdev@vger.kernel.org, edumazet@google.com,
	ncardwell@google.com, kuniyu@google.com, davem@davemloft.net,
	dsahern@kernel.org, pabeni@redhat.com, horms@kernel.org,
	quic_stranche@quicinc.com, quic_subashab@quicinc.com,
	linux-kernel@vger.kernel.org, karen.badiryan@broadcom.com,
	ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com,
	vamsi-krishna.brahmajosyula@broadcom.com, yin.ding@broadcom.com,
	tapas.kundu@broadcom.com
Subject: Re: [PATCH net] tcp: do not shrink window clamp when SO_RCVBUF is locked
Date: Tue, 28 Apr 2026 09:21:10 +0000	[thread overview]
Message-ID: <20260428092110.2280-1-ankit-aj.jain@broadcom.com> (raw)
In-Reply-To: <20260427131111.168ed0dc@kernel.org>

Hi Jakub,

Thank you for pointing this out.

I checked the logic again, I placed the SOCK_RCVBUF_LOCK check on
the outer if-statement. This successfully prevented
tcp_set_window_clamp() from crushing the window (fixing the
Java SWS bug), but it accidentally bypassed the tp->rcvq_space.space
bounds check as well. Because of this, the receive queue tracking got
out of sync when the test hit a negative window.

For v2, I will move the lock check inside the block so it only bypasses
tcp_set_window_clamp(), ensuring the rcvq_space.space limits still
execute as expected.

I will test the refined logic against my reproducer and the
tcp_rcv_neg_window.pkt script locally, and I will post the v2 series
in a new thread after the 24-hour cooldown.

Thanks,
Ankit

  reply	other threads:[~2026-04-28  9:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-27 15:27 [PATCH net] tcp: do not shrink window clamp when SO_RCVBUF is locked Ankit Jain
2026-04-27 15:38 ` Eric Dumazet
2026-04-27 20:11   ` Jakub Kicinski
2026-04-28  9:21     ` Ankit Jain [this message]
2026-04-28  8:47   ` Ankit Jain

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