From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755386AbaBGLwo (ORCPT ); Fri, 7 Feb 2014 06:52:44 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:42500 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752951AbaBGLwl (ORCPT ); Fri, 7 Feb 2014 06:52:41 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Christoph Paasch , "David S. Miller" , Luis Henriques Subject: [PATCH 3.11 217/233] tcp: metrics: Avoid duplicate entries with the same destination-IP Date: Fri, 7 Feb 2014 11:47:16 +0000 Message-Id: <1391773652-25214-218-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1391773652-25214-1-git-send-email-luis.henriques@canonical.com> References: <1391773652-25214-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Paasch commit 77f99ad16a07aa062c2d30fae57b1fee456f6ef6 upstream. Because the tcp-metrics is an RCU-list, it may be that two soft-interrupts are inside __tcp_get_metrics() for the same destination-IP at the same time. If this destination-IP is not yet part of the tcp-metrics, both soft-interrupts will end up in tcpm_new and create a new entry for this IP. So, we will have two tcp-metrics with the same destination-IP in the list. This patch checks twice __tcp_get_metrics(). First without holding the lock, then while holding the lock. The second one is there to confirm that the entry has not been added by another soft-irq while waiting for the spin-lock. Fixes: 51c5d0c4b169b (tcp: Maintain dynamic metrics in local cache.) Signed-off-by: Christoph Paasch Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/ipv4/tcp_metrics.c | 51 +++++++++++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 19 deletions(-) diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index 306dbd9..b500d2d 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -22,6 +22,9 @@ int sysctl_tcp_nometrics_save __read_mostly; +static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr, + struct net *net, unsigned int hash); + struct tcp_fastopen_metrics { u16 mss; u16 syn_loss:10; /* Recurring Fast Open SYN losses */ @@ -130,16 +133,41 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst, } } +#define TCP_METRICS_TIMEOUT (60 * 60 * HZ) + +static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst) +{ + if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT))) + tcpm_suck_dst(tm, dst, false); +} + +#define TCP_METRICS_RECLAIM_DEPTH 5 +#define TCP_METRICS_RECLAIM_PTR (struct tcp_metrics_block *) 0x1UL + static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst, struct inetpeer_addr *addr, - unsigned int hash, - bool reclaim) + unsigned int hash) { struct tcp_metrics_block *tm; struct net *net; + bool reclaim = false; spin_lock_bh(&tcp_metrics_lock); net = dev_net(dst->dev); + + /* While waiting for the spin-lock the cache might have been populated + * with this entry and so we have to check again. + */ + tm = __tcp_get_metrics(addr, net, hash); + if (tm == TCP_METRICS_RECLAIM_PTR) { + reclaim = true; + tm = NULL; + } + if (tm) { + tcpm_check_stamp(tm, dst); + goto out_unlock; + } + if (unlikely(reclaim)) { struct tcp_metrics_block *oldest; @@ -169,17 +197,6 @@ out_unlock: return tm; } -#define TCP_METRICS_TIMEOUT (60 * 60 * HZ) - -static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst) -{ - if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT))) - tcpm_suck_dst(tm, dst, false); -} - -#define TCP_METRICS_RECLAIM_DEPTH 5 -#define TCP_METRICS_RECLAIM_PTR (struct tcp_metrics_block *) 0x1UL - static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth) { if (tm) @@ -280,7 +297,6 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk, struct inetpeer_addr addr; unsigned int hash; struct net *net; - bool reclaim; addr.family = sk->sk_family; switch (addr.family) { @@ -300,13 +316,10 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk, hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log); tm = __tcp_get_metrics(&addr, net, hash); - reclaim = false; - if (tm == TCP_METRICS_RECLAIM_PTR) { - reclaim = true; + if (tm == TCP_METRICS_RECLAIM_PTR) tm = NULL; - } if (!tm && create) - tm = tcpm_new(dst, &addr, hash, reclaim); + tm = tcpm_new(dst, &addr, hash); else tcpm_check_stamp(tm, dst); -- 1.8.3.2