@@ -98,6 +98,45 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
if (!is_a_nulls(first))
first->pprev = &n->next;
}
+
+/**
+ * hlist_nulls_add_tail_rcu
+ * @n: the element to add to the hash list.
+ * @h: the list to add to.
+ *
+ * Description:
+ * Adds the specified element to the end of the specified hlist_nulls,
+ * while permitting racing traversals. NOTE: tail insertion requires
+ * list traversal.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_nulls_add_head_rcu()
+ * or hlist_nulls_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs. Regardless of the type of CPU, the
+ * list-traversal primitive must be guarded by rcu_read_lock().
+ */
+static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
+ struct hlist_nulls_head *h)
+{
+ struct hlist_nulls_node *i, *last = NULL;
+
+ for (i = hlist_nulls_first_rcu(h); !is_a_nulls(i);
+ i = hlist_nulls_next_rcu(i))
+ last = i;
+
+ if (last) {
+ n->next = last->next;
+ n->pprev = &last->next;
+ rcu_assign_pointer(hlist_nulls_next_rcu(last), n);
+ } else {
+ hlist_nulls_add_head_rcu(n, h);
+ }
+}
+
/**
* hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type
* @tpos: the type * to use as a loop cursor.
@@ -631,7 +631,11 @@ static inline void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)
static inline void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)
{
- hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
+ if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
+ sk->sk_family == AF_INET6)
+ hlist_nulls_add_tail_rcu(&sk->sk_nulls_node, list);
+ else
+ hlist_nulls_add_head_rcu(&sk->sk_nulls_node, list);
}
static inline void sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)
@@ -297,8 +297,13 @@ found:
hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
spin_lock(&hslot2->lock);
- hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
- &hslot2->head);
+ if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
+ sk->sk_family == AF_INET6)
+ hlist_nulls_add_tail_rcu(&udp_sk(sk)->udp_portaddr_node,
+ &hslot2->head);
+ else
+ hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
+ &hslot2->head);
hslot2->count++;
spin_unlock(&hslot2->lock);
}
This is a note to let you know that I have just added a patch titled soreuseport: fix ordering for mixed v4/v6 sockets to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 4aede5ae579cf45379425e1fdba994fdec4c9237 Mon Sep 17 00:00:00 2001 From: Craig Gallek <kraig@google.com> Date: Tue, 12 Apr 2016 13:11:25 -0400 Subject: soreuseport: fix ordering for mixed v4/v6 sockets MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit d894ba18d4e449b3a7f6eb491f16c9e02933736e ] With the SO_REUSEPORT socket option, it is possible to create sockets in the AF_INET and AF_INET6 domains which are bound to the same IPv4 address. This is only possible with SO_REUSEPORT and when not using IPV6_V6ONLY on the AF_INET6 sockets. Prior to the commits referenced below, an incoming IPv4 packet would always be routed to a socket of type AF_INET when this mixed-mode was used. After those changes, the same packet would be routed to the most recently bound socket (if this happened to be an AF_INET6 socket, it would have an IPv4 mapped IPv6 address). The change in behavior occurred because the recent SO_REUSEPORT optimizations short-circuit the socket scoring logic as soon as they find a match. They did not take into account the scoring logic that favors AF_INET sockets over AF_INET6 sockets in the event of a tie. To fix this problem, this patch changes the insertion order of AF_INET and AF_INET6 addresses in the TCP and UDP socket lists when the sockets have SO_REUSEPORT set. AF_INET sockets will be inserted at the head of the list and AF_INET6 sockets with SO_REUSEPORT set will always be inserted at the tail of the list. This will force AF_INET sockets to always be considered first. Fixes: e32ea7e74727 ("soreuseport: fast reuseport UDP socket selection") Fixes: 125e80b88687 ("soreuseport: fast reuseport TCP socket selection") Reported-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: Craig Gallek <kraig@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- include/linux/rculist_nulls.h | 39 +++++++++++++++++++++++++++++++++++++++ include/net/sock.h | 6 +++++- net/ipv4/udp.c | 9 +++++++-- 3 files changed, 51 insertions(+), 3 deletions(-) -- 2.7.4