From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B4D2C10F1D for ; Fri, 23 Dec 2022 01:56:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235758AbiLWB4L (ORCPT ); Thu, 22 Dec 2022 20:56:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235659AbiLWBz6 (ORCPT ); Thu, 22 Dec 2022 20:55:58 -0500 Received: from smtp-fw-33001.amazon.com (smtp-fw-33001.amazon.com [207.171.190.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C58C18343 for ; Thu, 22 Dec 2022 17:55:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1671760558; x=1703296558; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=efW+HFr3dEcIF1p50QeA1NeF7upEORFnMAcRNn1AG/s=; b=O4KHkw5x2qkT4VsErupGn2bYxIuztLXQacjsZlk27vs5P6QijEo+znPm QjFOwGO/0Tc6Vhck4DIYanaS4w/iDzPn+AP1DvSPvxgMHPvaOXV/emts9 41esbF1ABRA1WkOg6If572Vxt4PBg3eFmNvgbTkX5sjpmOL/Ltg8XC51m 0=; X-IronPort-AV: E=Sophos;i="5.96,267,1665446400"; d="scan'208";a="250419383" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-pdx-2a-m6i4x-3ef535ca.us-west-2.amazon.com) ([10.43.8.6]) by smtp-border-fw-33001.sea14.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Dec 2022 01:55:52 +0000 Received: from EX13MTAUWB002.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-pdx-2a-m6i4x-3ef535ca.us-west-2.amazon.com (Postfix) with ESMTPS id C3F0C62160; Fri, 23 Dec 2022 01:55:49 +0000 (UTC) Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX13MTAUWB002.ant.amazon.com (10.43.161.202) with Microsoft SMTP Server (TLS) id 15.0.1497.42; Fri, 23 Dec 2022 01:55:49 +0000 Received: from 88665a182662.ant.amazon.com (10.43.161.114) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.20; Fri, 23 Dec 2022 01:55:45 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , Subject: Re: [PATCH RFC net 1/2] tcp: Add TIME_WAIT sockets in bhash2. Date: Fri, 23 Dec 2022 10:55:37 +0900 Message-ID: <20221223015537.4249-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.43.161.114] X-ClientProxiedBy: EX13D37UWC003.ant.amazon.com (10.43.162.183) To EX19D004ANA001.ant.amazon.com (10.37.240.138) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Joanne Koong Date: Thu, 22 Dec 2022 16:25:10 -0800 > On Thu, Dec 22, 2022 at 3:27 PM Kuniyuki Iwashima wrote: > > > > From: Joanne Koong > > Date: Thu, 22 Dec 2022 13:46:57 -0800 > > > On Thu, Dec 22, 2022 at 7:06 AM Paolo Abeni wrote: > > > > > > > > On Thu, 2022-12-22 at 00:12 +0900, Kuniyuki Iwashima wrote: > > > > > Jiri Slaby reported regression of bind() with a simple repro. [0] > > > > > > > > > > The repro creates a TIME_WAIT socket and tries to bind() a new socket > > > > > with the same local address and port. Before commit 28044fc1d495 ("net: > > > > > Add a bhash2 table hashed by port and address"), the bind() failed with > > > > > -EADDRINUSE, but now it succeeds. > > > > > > > > > > The cited commit should have put TIME_WAIT sockets into bhash2; otherwise, > > > > > inet_bhash2_conflict() misses TIME_WAIT sockets when validating bind() > > > > > requests if the address is not a wildcard one. > > > > > > (resending my reply because it wasn't in plaintext mode) > > > > > > Thanks for adding this! I hadn't realized TIME_WAIT sockets also are > > > considered when checking against inet bind conflicts. > > > > > > > > > > > How does keeping the timewait sockets inside bhash2 affect the bind > > > > loopup performance? I fear that could defeat completely the goal of > > > > 28044fc1d495, on quite busy server we could have quite a bit of tw with > > > > the same address/port. If so, we could even consider reverting > > > > 28044fc1d495. > > > > It will slow down along the number of twsk, but I think it's still faster > > than bhash if we listen() on multiple IP. If we don't, bhash is always > > faster because of bhash2's additional locking. However, this is the > > nature of bhash2 from the beginning. > > > > > > > > > > > > > > Can you clarify what you mean by bind loopup? > > > > I think it means just bhash2 traversal. (s/loopup/lookup/) > > > > > > > > > > [0]: https://lore.kernel.org/netdev/6b971a4e-c7d8-411e-1f92-fda29b5b2fb9@kernel.org/ > > > > > > > > > > Fixes: 28044fc1d495 ("net: Add a bhash2 table hashed by port and address") > > > > > Reported-by: Jiri Slaby > > > > > Signed-off-by: Kuniyuki Iwashima > > > > > --- > > > > > include/net/inet_timewait_sock.h | 2 ++ > > > > > include/net/sock.h | 5 +++-- > > > > > net/ipv4/inet_hashtables.c | 5 +++-- > > > > > net/ipv4/inet_timewait_sock.c | 31 +++++++++++++++++++++++++++++-- > > > > > 4 files changed, 37 insertions(+), 6 deletions(-) > > > > > > > > > > diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h > > > > > index 5b47545f22d3..c46ed239ad9a 100644 > > > > > --- a/include/net/inet_timewait_sock.h > > > > > +++ b/include/net/inet_timewait_sock.h > > > > > @@ -44,6 +44,7 @@ struct inet_timewait_sock { > > > > > #define tw_bound_dev_if __tw_common.skc_bound_dev_if > > > > > #define tw_node __tw_common.skc_nulls_node > > > > > #define tw_bind_node __tw_common.skc_bind_node > > > > > +#define tw_bind2_node __tw_common.skc_bind2_node > > > > > #define tw_refcnt __tw_common.skc_refcnt > > > > > #define tw_hash __tw_common.skc_hash > > > > > #define tw_prot __tw_common.skc_prot > > > > > @@ -73,6 +74,7 @@ struct inet_timewait_sock { > > > > > u32 tw_priority; > > > > > struct timer_list tw_timer; > > > > > struct inet_bind_bucket *tw_tb; > > > > > + struct inet_bind2_bucket *tw_tb2; > > > > > }; > > > > > #define tw_tclass tw_tos > > > > > > > > > > diff --git a/include/net/sock.h b/include/net/sock.h > > > > > index dcd72e6285b2..aaec985c1b5b 100644 > > > > > --- a/include/net/sock.h > > > > > +++ b/include/net/sock.h > > > > > @@ -156,6 +156,7 @@ typedef __u64 __bitwise __addrpair; > > > > > * @skc_tw_rcv_nxt: (aka tw_rcv_nxt) TCP window next expected seq number > > > > > * [union with @skc_incoming_cpu] > > > > > * @skc_refcnt: reference count > > > > > + * @skc_bind2_node: bind node in the bhash2 table > > > > > * > > > > > * This is the minimal network layer representation of sockets, the header > > > > > * for struct sock and struct inet_timewait_sock. > > > > > @@ -241,6 +242,7 @@ struct sock_common { > > > > > u32 skc_window_clamp; > > > > > u32 skc_tw_snd_nxt; /* struct tcp_timewait_sock */ > > > > > }; > > > > > + struct hlist_node skc_bind2_node; > > > > > > > > I *think* it would be better adding a tw_bind2_node field to the > > > > inet_timewait_sock struct, so that we leave unmodified the request > > > > socket and we don't change the struct sock binary layout. That could > > > > affect performances moving hot fields on different cachelines. > > > > > > > +1. The rest of this patch LGTM. > > > > Then we can't use sk_for_each_bound_bhash2(), or we have to guarantee this. > > > > BUILD_BUG_ON(offsetof(struct sock, sk_bind2_node), > > offsetof(struct inet_timewait_sock, tw_bind2_node)) > > > > Considering the number of members in struct sock, at least we have > > to move sk_bind2_node forward. > > > > Another option is to have another TIME_WAIT list in inet_bind2_bucket like > > tb2->deathrow or something. sk_for_each_bound_bhash2() is used only in > > inet_bhash2_conflict(), so I think this is feasible. > > Oh I see, thanks for clarifying! > > I think we could also check sk_state (which is in __sk_common already) > and if it's TCP_TIME_WAIT, then we know sk is at offsetof(struct > inet_timewait_sock, tw_bind2_node), whereas otherwise it's at > offsetof(struct sock, sk_bind2_node). This seems simpler/cleaner to me > than the other approaches. What are your thoughts? Sorry, I don't get it. You mean we can check sk_state first and change how we traverse ? But then we cannot know the offset of sk_state if we don't know if the socket is TIME_WAIT ... ?