/**
* This is main body of the socket close function in Sync Sockets.
*
* inet_release() can sleep (as well as tcp_close()), so we make our own
* non-sleepable socket closing.
*
* This function must be used only for data sockets.
* Use standard sock_release() for listening sockets.
*
* In most cases it is called in softirq context and from ksoftirqd which
* processes data from the socket (RSS and RPS distribute packets that way).
*
* Note: it used to be called in process context as well, at the time when
* Tempesta starts or stops. That's not the case right now, but it may change.
*
* TODO In some cases we need to close socket agresively w/o FIN_WAIT_2 state,
* e.g. by sending RST. So we need to add second parameter to the function
* which says how to close the socket.
* One of the examples is rcl_req_limit() (it should reset connections).
* See tcp_sk(sk)->linger2 processing in standard tcp_close().
*
* Called with locked socket.
*/
static void
ss_do_close(struct sock *sk)
{
struct sk_buff *skb;
int data_was_unread = 0;
int state;
if (unlikely(!sk))
return;
SS_DBG("Close socket %p (%s): cpu=%d account=%d refcnt=%d\n",
sk, ss_statename[sk->sk_state], smp_processor_id(),
sk_has_account(sk), atomic_read(&sk->sk_refcnt));
assert_spin_locked(&sk->sk_lock.slock);
ss_sock_cpu_check(sk);
BUG_ON(sk->sk_state == TCP_LISTEN);
/* We must return immediately, so LINGER option is meaningless. */
WARN_ON(sock_flag(sk, SOCK_LINGER));
/* We don't support virtual containers, so TCP_REPAIR is prohibited. */
WARN_ON(tcp_sk(sk)->repair);
/* The socket must have atomic allocation mask. */
WARN_ON(!(sk->sk_allocation & GFP_ATOMIC));
/* The below is mostly copy-paste from tcp_close(). */
sk->sk_shutdown = SHUTDOWN_MASK;
while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
tcp_hdr(skb)->fin;
data_was_unread += len;
SS_DBG("free rcv skb %p\n", skb);
__kfree_skb(skb);
}
sk_mem_reclaim(sk);
if (sk->sk_state == TCP_CLOSE)
goto adjudge_to_death;
if (data_was_unread) {
NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
tcp_set_state(sk, TCP_CLOSE);
tcp_send_active_reset(sk, sk->sk_allocation);
}
else if (tcp_close_state(sk)) {
/* The code below is taken from tcp_send_fin(). */
struct tcp_sock *tp = tcp_sk(sk);
int mss_now = tcp_current_mss(sk);
skb = tcp_write_queue_tail(sk);
if (tcp_send_head(sk) != NULL) {
/* Send FIN with data if we have any. */
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
TCP_SKB_CB(skb)->end_seq++;
tp->write_seq++;
}
else {
/* No data to send in the socket, allocate new skb. */
skb = alloc_skb_fclone(MAX_TCP_HEADER,
sk->sk_allocation);
if (!skb) {
SS_WARN("can't send FIN due to bad alloc");
} else {
skb_reserve(skb, MAX_TCP_HEADER);
tcp_init_nondata_skb(skb, tp->write_seq,
TCPHDR_ACK | TCPHDR_FIN);
tcp_queue_skb(sk, skb);
}
}
__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);
}
adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
/*
* SS sockets are processed in softirq only,
* so backlog queue should be empty.
*/
WARN_ON(sk->sk_backlog.tail);
percpu_counter_inc(sk->sk_prot->orphan_count);
if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
return;
if (sk->sk_state == TCP_FIN_WAIT2) {
const int tmo = tcp_fin_time(sk);
if (tmo > TCP_TIMEWAIT_LEN) {
inet_csk_reset_keepalive_timer(sk,
tmo - TCP_TIMEWAIT_LEN);
} else {
tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
return;
}
}
if (sk->sk_state != TCP_CLOSE) {
sk_mem_reclaim(sk);
if (tcp_check_oom(sk, 0)) {
tcp_set_state(sk, TCP_CLOSE);
tcp_send_active_reset(sk, GFP_ATOMIC);
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPABORTONMEMORY);
}
}
if (sk->sk_state == TCP_CLOSE) {
struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
if (req != NULL)
reqsk_fastopen_remove(sk, req, false);
inet_csk_destroy_sock(sk);
}
}
struct sk_buff *rtl_tcp_write_queue_tail(const struct sock *sk)
{
return tcp_write_queue_tail(sk);
}
