From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 282EF2773F for ; Sat, 22 Nov 2025 12:59:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763816371; cv=none; b=PqaRvfCziikQjEQi00K5SiQmMVMgjS+y9HD/cNLn2JHHbTWH0vUsxJhiw4U8alXypKX7ThF5lZ4j1XvWxbj7dAaSht7hxrnnU9hTMS3GtXHMj7eLt1t5lGb9B7tf7478k4N7ULY08frYYqbDrXmVqaz5Mub6K5C8wZJ2UR9JWKk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763816371; c=relaxed/simple; bh=B3kW9KXHwZ90SF6OoXrJsEdPmwanb9+gu2u+puL+rSE=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=aNFM/ykRBZhSOJvcUmOtC3MuRsNwytqf0rwM/gLMeUzuCpeoUJY87g+hLPnJY8IsNEbLWaSNpxBKjD6vO15AnxHQwRReZfEmt0KQmvfbVLv7RyrBCSxJhwifRIWYaS0HIgNIm2PXaJlZEd8nWwIckZiU8yoFBxIsG17dbNzCGnw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rhn6pP30; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rhn6pP30" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1EEDC4CEF5; Sat, 22 Nov 2025 12:59:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763816370; bh=B3kW9KXHwZ90SF6OoXrJsEdPmwanb9+gu2u+puL+rSE=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=rhn6pP30j85R16Pimii/r+9yPIDENX/FgkKSA/af+sshrJiU9jS+IWS40skbIoazB z0L698KmOTRTBludXEuYsgoGIbgbXvYN0kLSYE3Gw5ZBia2aasrnEORg9eqUZ4XjnO uAQE5ViYqJSkX8MqTjCbMK2Zjpx85ul58ESP6KuE1jaLJn1ri57cndIGvU+Db0dWIo ODApdrAfK9ZnfXUFWjJI+qNn0W46edWPBVsGGdQonWTMmn0qCZdmXJEqgGe6r+bMkB ArfTuODNKCCcGka+TfMFJrTFsTPFul2RbRZGwKKOcTCpzxm4dO05MnWkDGkv34wkFi crOWfr6aIz8IQ== Message-ID: Subject: Re: [PATCH mptcp-net] mptcp: clear scheduled subflows on retransmit From: Geliang Tang To: Paolo Abeni , mptcp@lists.linux.dev Cc: dcaratti@redhat.com Date: Sat, 22 Nov 2025 20:59:27 +0800 In-Reply-To: <30e5325f37026b870cd0d0765d5d47c8a68fced9.1763676964.git.pabeni@redhat.com> References: <30e5325f37026b870cd0d0765d5d47c8a68fced9.1763676964.git.pabeni@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.56.2-4 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Paolo, On Thu, 2025-11-20 at 23:16 +0100, Paolo Abeni wrote: > When __mptcp_retrans() kicks-in, it schedules one or more subflow for > retransmission, but such subflows could be actually left alone if > there > is no more data to retransmit and/or in case of concurrent fallback. > > Scheduled subflows could be processed much later in time, i.e. when > new > data will be transmitted, leading to bad subflow selection. > > Explicitly clear all scheduled subflows before leaving the > retransmission > function. > > Fixes: ee2708aedad0 ("mptcp: use get_retrans wrapper") > Signed-off-by: Paolo Abeni > --- >  net/mptcp/protocol.c | 13 +++++++++++-- >  1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 6f4220c8b5bb..3b327e9ccb78 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -2763,7 +2763,7 @@ static void __mptcp_retrans(struct sock *sk) >   } >   >   if (!mptcp_send_head(sk)) > - return; > + goto clear_scheduled; >   >   goto reset_timer; >   } > @@ -2794,7 +2794,7 @@ static void __mptcp_retrans(struct sock *sk) >   if (__mptcp_check_fallback(msk)) { >   spin_unlock_bh(&msk->fallback_lock); >   release_sock(ssk); > - return; > + goto clear_scheduled; >   } >   >   while (info.sent < info.limit) { > @@ -2826,6 +2826,15 @@ static void __mptcp_retrans(struct sock *sk) >   >   if (!mptcp_rtx_timer_pending(sk)) >   mptcp_reset_rtx_timer(sk); > + > +clear_scheduled: > + /* If no rtx data was available or in case of fallback, > there > + * could be left-over scheduled subflows; clear them all > + * or later xmit could use bad ones > + */ > + mptcp_for_each_subflow(msk, subflow) > + if (READ_ONCE(subflow->scheduled)) > + mptcp_subflow_set_scheduled(subflow, false); >  } If this __mptcp_retrans() needs to clear scheduled subflows, then shouldn't similar this clear_scheduled operations also be added at the end of both the __mptcp_push_pending() and __mptcp_subflow_push_pending()? Thanks, -Geliang >   >  /* schedule the timeout timer for the relevant event: either close > timeout