From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next 1/5] tcp: Create list of TFO-contexts Date: Sun, 16 Dec 2018 22:31:41 -0800 Message-ID: <4f327eec-ce46-c871-0ca5-26d6939b9faf@gmail.com> References: <20181214224007.54813-1-cpaasch@apple.com> <20181214224007.54813-2-cpaasch@apple.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: Eric Dumazet , Yuchung Cheng , David Miller To: Christoph Paasch , netdev@vger.kernel.org Return-path: Received: from mail-wr1-f68.google.com ([209.85.221.68]:46147 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726256AbeLQGbo (ORCPT ); Mon, 17 Dec 2018 01:31:44 -0500 Received: by mail-wr1-f68.google.com with SMTP id l9so10978135wrt.13 for ; Sun, 16 Dec 2018 22:31:43 -0800 (PST) In-Reply-To: <20181214224007.54813-2-cpaasch@apple.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 12/14/2018 02:40 PM, Christoph Paasch wrote: > Instead of having a single TFO-context, we now have a list of > tcp_fastopen_context, bounded by TCP_FASTOPEN_CTXT_LEN (set to 2). > > This enables us to do a rolling TFO-key update that allows the server to > accept old cookies and at the same time announce new ones to the client > (see follow-up patch). > > Signed-off-by: Christoph Paasch > --- > include/net/tcp.h | 2 ++ > net/ipv4/tcp_fastopen.c | 52 +++++++++++++++++++++++++++++++++++++++++++++---- > 2 files changed, 50 insertions(+), 4 deletions(-) > > diff --git a/include/net/tcp.h b/include/net/tcp.h > index e0a65c067662..e629ea2e6c9d 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -1622,9 +1622,11 @@ bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, > struct tcp_fastopen_cookie *cookie); > bool tcp_fastopen_defer_connect(struct sock *sk, int *err); > #define TCP_FASTOPEN_KEY_LENGTH 16 > +#define TCP_FASTOPEN_CTXT_LEN 2 > > /* Fastopen key context */ > struct tcp_fastopen_context { > + struct tcp_fastopen_context __rcu *next; > struct crypto_cipher *tfm; > __u8 key[TCP_FASTOPEN_KEY_LENGTH]; > struct rcu_head rcu; > diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c > index 018a48477355..c52d5b8eabf0 100644 > --- a/net/ipv4/tcp_fastopen.c > +++ b/net/ipv4/tcp_fastopen.c > @@ -37,8 +37,14 @@ static void tcp_fastopen_ctx_free(struct rcu_head *head) > { > struct tcp_fastopen_context *ctx = > container_of(head, struct tcp_fastopen_context, rcu); > - crypto_free_cipher(ctx->tfm); > - kfree(ctx); > + > + while (ctx) { > + struct tcp_fastopen_context *prev = ctx; > + /* We own ctx, thus no need to hold the Fastopen-lock */ > + ctx = rcu_dereference_protected(ctx->next, 1); > + crypto_free_cipher(prev->tfm); > + kfree(prev); > + } > It seems this function does not need to be changed, since at most one context should be freed per run ?