@@ -1773,9 +1773,11 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst)
static inline void
sk_dst_set(struct sock *sk, struct dst_entry *dst)
{
- spin_lock(&sk->sk_dst_lock);
- __sk_dst_set(sk, dst);
- spin_unlock(&sk->sk_dst_lock);
+ struct dst_entry *old_dst;
+
+ sk_tx_queue_clear(sk);
+ old_dst = xchg(&sk->sk_dst_cache, dst);
+ dst_release(old_dst);
}
static inline void
@@ -1787,9 +1789,7 @@ __sk_dst_reset(struct sock *sk)
static inline void
sk_dst_reset(struct sock *sk)
{
- spin_lock(&sk->sk_dst_lock);
- __sk_dst_reset(sk);
- spin_unlock(&sk->sk_dst_lock);
+ sk_dst_set(sk, NULL);
}
extern struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie);
@@ -1031,20 +1031,21 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
const struct iphdr *iph = (const struct iphdr *) skb->data;
struct flowi4 fl4;
struct rtable *rt;
- struct dst_entry *dst;
+ struct dst_entry *odst = NULL;
bool new = false;
bh_lock_sock(sk);
- rt = (struct rtable *) __sk_dst_get(sk);
+ odst = sk_dst_get(sk);
- if (sock_owned_by_user(sk) || !rt) {
+ if (sock_owned_by_user(sk) || !odst) {
__ipv4_sk_update_pmtu(skb, sk, mtu);
goto out;
}
__build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
- if (!__sk_dst_check(sk, 0)) {
+ rt = (struct rtable *)odst;
+ if (odst->obsolete && odst->ops->check(odst, 0) == NULL) {
rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
if (IS_ERR(rt))
goto out;
@@ -1054,8 +1055,7 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
__ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
- dst = dst_check(&rt->dst, 0);
- if (!dst) {
+ if (!dst_check(&rt->dst, 0)) {
if (new)
dst_release(&rt->dst);
@@ -1067,10 +1067,11 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
}
if (new)
- __sk_dst_set(sk, &rt->dst);
+ sk_dst_set(sk, &rt->dst);
out:
bh_unlock_sock(sk);
+ dst_release(odst);
}
EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
This is a note to let you know that I have just added a patch titled ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 72797c68b63d02dca83b2096fe48e364facbcb50 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@google.com> Date: Mon, 30 Jun 2014 01:26:23 -0700 Subject: ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix commit 7f502361531e9eecb396cf99bdc9e9a59f7ebd7f upstream. We have two different ways to handle changes to sk->sk_dst First way (used by TCP) assumes socket lock is owned by caller, and use no extra lock : __sk_dst_set() & __sk_dst_reset() Another way (used by UDP) uses sk_dst_lock because socket lock is not always taken. Note that sk_dst_lock is not softirq safe. These ways are not inter changeable for a given socket type. ipv4_sk_update_pmtu(), added in linux-3.8, added a race, as it used the socket lock as synchronization, but users might be UDP sockets. Instead of converting sk_dst_lock to a softirq safe version, use xchg() as we did for sk_rx_dst in commit e47eb5dfb296b ("udp: ipv4: do not use sk_dst_lock from softirq context") In a follow up patch, we probably can remove sk_dst_lock, as it is only used in IPv6. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Fixes: 9cb3a50c5f63e ("ipv4: Invalidate the socket cached route on pmtu events if possible") Signed-off-by: David S. Miller <davem@davemloft.net> [ luis: backported to 3.11: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- include/net/sock.h | 12 ++++++------ net/ipv4/route.c | 15 ++++++++------- 2 files changed, 14 insertions(+), 13 deletions(-) -- 1.9.1