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Subject[PATCH v1 bpf-next 05/11] tcp: Migrate TCP_NEW_SYN_RECV requests.
Date
This patch renames reuseport_select_sock() to __reuseport_select_sock() and
adds two wrapper function of it to pass the migration type defined in the
previous commit.

reuseport_select_sock : BPF_SK_REUSEPORT_MIGRATE_NO
reuseport_select_migrated_sock : BPF_SK_REUSEPORT_MIGRATE_REQUEST

As mentioned before, we have to select a new listener for TCP_NEW_SYN_RECV
requests at receiving the final ACK or sending a SYN+ACK. Therefore, this
patch also changes the code to call reuseport_select_migrated_sock() even
if the listening socket is TCP_CLOSE. If we can pick out a listening socket
from the reuseport group, we rewrite request_sock.rsk_listener and resume
processing the request.

Reviewed-by: Benjamin Herrenschmidt <benh@amazon.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
---
include/net/inet_connection_sock.h | 12 +++++++++++
include/net/request_sock.h | 13 ++++++++++++
include/net/sock_reuseport.h | 8 +++----
net/core/sock_reuseport.c | 34 ++++++++++++++++++++++++------
net/ipv4/inet_connection_sock.c | 13 ++++++++++--
net/ipv4/tcp_ipv4.c | 9 ++++++--
net/ipv6/tcp_ipv6.c | 9 ++++++--
7 files changed, 81 insertions(+), 17 deletions(-)

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 2ea2d743f8fc..1e0958f5eb21 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -272,6 +272,18 @@ static inline void inet_csk_reqsk_queue_added(struct sock *sk)
reqsk_queue_added(&inet_csk(sk)->icsk_accept_queue);
}

+static inline void inet_csk_reqsk_queue_migrated(struct sock *sk,
+ struct sock *nsk,
+ struct request_sock *req)
+{
+ reqsk_queue_migrated(&inet_csk(sk)->icsk_accept_queue,
+ &inet_csk(nsk)->icsk_accept_queue,
+ req);
+ sock_put(sk);
+ sock_hold(nsk);
+ req->rsk_listener = nsk;
+}
+
static inline int inet_csk_reqsk_queue_len(const struct sock *sk)
{
return reqsk_queue_len(&inet_csk(sk)->icsk_accept_queue);
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 29e41ff3ec93..d18ba0b857cc 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -226,6 +226,19 @@ static inline void reqsk_queue_added(struct request_sock_queue *queue)
atomic_inc(&queue->qlen);
}

+static inline void reqsk_queue_migrated(struct request_sock_queue *old_accept_queue,
+ struct request_sock_queue *new_accept_queue,
+ const struct request_sock *req)
+{
+ atomic_dec(&old_accept_queue->qlen);
+ atomic_inc(&new_accept_queue->qlen);
+
+ if (req->num_timeout == 0) {
+ atomic_dec(&old_accept_queue->young);
+ atomic_inc(&new_accept_queue->young);
+ }
+}
+
static inline int reqsk_queue_len(const struct request_sock_queue *queue)
{
return atomic_read(&queue->qlen);
diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
index 09a1b1539d4c..a48259a974be 100644
--- a/include/net/sock_reuseport.h
+++ b/include/net/sock_reuseport.h
@@ -32,10 +32,10 @@ extern int reuseport_alloc(struct sock *sk, bool bind_inany);
extern int reuseport_add_sock(struct sock *sk, struct sock *sk2,
bool bind_inany);
extern struct sock *reuseport_detach_sock(struct sock *sk);
-extern struct sock *reuseport_select_sock(struct sock *sk,
- u32 hash,
- struct sk_buff *skb,
- int hdr_len);
+extern struct sock *reuseport_select_sock(struct sock *sk, u32 hash,
+ struct sk_buff *skb, int hdr_len);
+extern struct sock *reuseport_select_migrated_sock(struct sock *sk, u32 hash,
+ struct sk_buff *skb);
extern int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog);
extern int reuseport_detach_prog(struct sock *sk);

diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 60d7c1f28809..b4fe0829c9ab 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -202,7 +202,7 @@ int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany)
}

reuse->socks[reuse->num_socks] = sk;
- /* paired with smp_rmb() in reuseport_select_sock() */
+ /* paired with smp_rmb() in __reuseport_select_sock() */
smp_wmb();
reuse->num_socks++;
rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
@@ -313,12 +313,13 @@ static struct sock *run_bpf_filter(struct sock_reuseport *reuse, u16 socks,
* @hdr_len: BPF filter expects skb data pointer at payload data. If
* the skb does not yet point at the payload, this parameter represents
* how far the pointer needs to advance to reach the payload.
+ * @migration: represents if it is selecting a listener for SYN or
+ * migrating ESTABLISHED/SYN_RECV sockets or NEW_SYN_RECV socket.
* Returns a socket that should receive the packet (or NULL on error).
*/
-struct sock *reuseport_select_sock(struct sock *sk,
- u32 hash,
- struct sk_buff *skb,
- int hdr_len)
+struct sock *__reuseport_select_sock(struct sock *sk, u32 hash,
+ struct sk_buff *skb, int hdr_len,
+ u8 migration)
{
struct sock_reuseport *reuse;
struct bpf_prog *prog;
@@ -332,13 +333,19 @@ struct sock *reuseport_select_sock(struct sock *sk,
if (!reuse)
goto out;

- prog = rcu_dereference(reuse->prog);
socks = READ_ONCE(reuse->num_socks);
if (likely(socks)) {
/* paired with smp_wmb() in reuseport_add_sock() */
smp_rmb();

- if (!prog || !skb)
+ prog = rcu_dereference(reuse->prog);
+ if (!prog)
+ goto select_by_hash;
+
+ if (migration)
+ goto out;
+
+ if (!skb)
goto select_by_hash;

if (prog->type == BPF_PROG_TYPE_SK_REUSEPORT)
@@ -367,8 +374,21 @@ struct sock *reuseport_select_sock(struct sock *sk,
rcu_read_unlock();
return sk2;
}
+
+struct sock *reuseport_select_sock(struct sock *sk, u32 hash,
+ struct sk_buff *skb, int hdr_len)
+{
+ return __reuseport_select_sock(sk, hash, skb, hdr_len, BPF_SK_REUSEPORT_MIGRATE_NO);
+}
EXPORT_SYMBOL(reuseport_select_sock);

+struct sock *reuseport_select_migrated_sock(struct sock *sk, u32 hash,
+ struct sk_buff *skb)
+{
+ return __reuseport_select_sock(sk, hash, skb, 0, BPF_SK_REUSEPORT_MIGRATE_REQUEST);
+}
+EXPORT_SYMBOL(reuseport_select_migrated_sock);
+
int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog)
{
struct sock_reuseport *reuse;
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 361efe55b1ad..e71653c6eae2 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -743,8 +743,17 @@ static void reqsk_timer_handler(struct timer_list *t)
struct request_sock_queue *queue = &icsk->icsk_accept_queue;
int max_syn_ack_retries, qlen, expire = 0, resend = 0;

- if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
- goto drop;
+ if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
+ sk_listener = reuseport_select_migrated_sock(sk_listener,
+ req_to_sk(req)->sk_hash, NULL);
+ if (!sk_listener) {
+ sk_listener = req->rsk_listener;
+ goto drop;
+ }
+ inet_csk_reqsk_queue_migrated(req->rsk_listener, sk_listener, req);
+ icsk = inet_csk(sk_listener);
+ queue = &icsk->icsk_accept_queue;
+ }

max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
/* Normally all the openreqs are young and become mature
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index e4b31e70bd30..9a9aa27c6069 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1973,8 +1973,13 @@ int tcp_v4_rcv(struct sk_buff *skb)
goto csum_error;
}
if (unlikely(sk->sk_state != TCP_LISTEN)) {
- inet_csk_reqsk_queue_drop_and_put(sk, req);
- goto lookup;
+ nsk = reuseport_select_migrated_sock(sk, req_to_sk(req)->sk_hash, skb);
+ if (!nsk) {
+ inet_csk_reqsk_queue_drop_and_put(sk, req);
+ goto lookup;
+ }
+ inet_csk_reqsk_queue_migrated(sk, nsk, req);
+ sk = nsk;
}
/* We own a reference on the listener, increase it again
* as we might lose it too soon.
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 992cbf3eb9e3..ff11f3c0cb96 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1635,8 +1635,13 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto csum_error;
}
if (unlikely(sk->sk_state != TCP_LISTEN)) {
- inet_csk_reqsk_queue_drop_and_put(sk, req);
- goto lookup;
+ nsk = reuseport_select_migrated_sock(sk, req_to_sk(req)->sk_hash, skb);
+ if (!nsk) {
+ inet_csk_reqsk_queue_drop_and_put(sk, req);
+ goto lookup;
+ }
+ inet_csk_reqsk_queue_migrated(sk, nsk, req);
+ sk = nsk;
}
sock_hold(sk);
refcounted = true;
--
2.17.2 (Apple Git-113)
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