This is a note to let you know that I've just added the patch titled
tcp: metrics: Avoid duplicate entries with the same destination-IP
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-metrics-avoid-duplicate-entries-with-the-same-destination-ip.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From foo@baz Tue Feb 4 09:07:36 PST 2014
From: Christoph Paasch <[email protected]>
Date: Thu, 16 Jan 2014 20:01:21 +0100
Subject: tcp: metrics: Avoid duplicate entries with the same destination-IP
From: Christoph Paasch <[email protected]>
[ Upstream commit 77f99ad16a07aa062c2d30fae57b1fee456f6ef6 ]
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 <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/ipv4/tcp_metrics.c | 51 ++++++++++++++++++++++++++++++-------------------
1 file changed, 32 insertions(+), 19 deletions(-)
--- 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_met
}
}
+#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
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
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);
Patches currently in stable-queue which might be from
[email protected] are
queue-3.10/tcp-metrics-avoid-duplicate-entries-with-the-same-destination-ip.patch
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