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Diffstat (limited to 'net/ipv4/tcp_timer.c')
-rw-r--r--net/ipv4/tcp_timer.c108
1 files changed, 79 insertions, 29 deletions
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 49bc474f8e35..f712b411f6ed 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -24,25 +24,37 @@
int sysctl_tcp_thin_linear_timeouts __read_mostly;
+/**
+ * tcp_write_err() - close socket and save error info
+ * @sk: The socket the error has appeared on.
+ *
+ * Returns: Nothing (void)
+ */
+
static void tcp_write_err(struct sock *sk)
{
sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
sk->sk_error_report(sk);
tcp_done(sk);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONTIMEOUT);
}
-/* Do not allow orphaned sockets to eat all our resources.
- * This is direct violation of TCP specs, but it is required
- * to prevent DoS attacks. It is called when a retransmission timeout
- * or zero probe timeout occurs on orphaned socket.
+/**
+ * tcp_out_of_resources() - Close socket if out of resources
+ * @sk: pointer to current socket
+ * @do_reset: send a last packet with reset flag
*
- * Criteria is still not confirmed experimentally and may change.
- * We kill the socket, if:
- * 1. If number of orphaned sockets exceeds an administratively configured
- * limit.
- * 2. If we have strong memory pressure.
+ * Do not allow orphaned sockets to eat all our resources.
+ * This is direct violation of TCP specs, but it is required
+ * to prevent DoS attacks. It is called when a retransmission timeout
+ * or zero probe timeout occurs on orphaned socket.
+ *
+ * Criteria is still not confirmed experimentally and may change.
+ * We kill the socket, if:
+ * 1. If number of orphaned sockets exceeds an administratively configured
+ * limit.
+ * 2. If we have strong memory pressure.
*/
static int tcp_out_of_resources(struct sock *sk, bool do_reset)
{
@@ -68,13 +80,17 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
if (do_reset)
tcp_send_active_reset(sk, GFP_ATOMIC);
tcp_done(sk);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
return 1;
}
return 0;
}
-/* Calculate maximal number or retries on an orphaned socket. */
+/**
+ * tcp_orphan_retries() - Returns maximal number of retries on an orphaned socket
+ * @sk: Pointer to the current socket.
+ * @alive: bool, socket alive state
+ */
static int tcp_orphan_retries(struct sock *sk, bool alive)
{
int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */
@@ -115,10 +131,22 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
}
}
-/* This function calculates a "timeout" which is equivalent to the timeout of a
- * TCP connection after "boundary" unsuccessful, exponentially backed-off
+
+/**
+ * retransmits_timed_out() - returns true if this connection has timed out
+ * @sk: The current socket
+ * @boundary: max number of retransmissions
+ * @timeout: A custom timeout value.
+ * If set to 0 the default timeout is calculated and used.
+ * Using TCP_RTO_MIN and the number of unsuccessful retransmits.
+ * @syn_set: true if the SYN Bit was set.
+ *
+ * The default "timeout" value this function can calculate and use
+ * is equivalent to the timeout of a TCP Connection
+ * after "boundary" unsuccessful, exponentially backed-off
* retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if
* syn_set flag is set.
+ *
*/
static bool retransmits_timed_out(struct sock *sk,
unsigned int boundary,
@@ -162,8 +190,8 @@ static int tcp_write_timeout(struct sock *sk)
if (tp->syn_fastopen || tp->syn_data)
tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
if (tp->syn_data && icsk->icsk_retransmits == 1)
- NET_INC_STATS_BH(sock_net(sk),
- LINUX_MIB_TCPFASTOPENACTIVEFAIL);
+ NET_INC_STATS(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENACTIVEFAIL);
}
retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries;
syn_set = true;
@@ -178,8 +206,8 @@ static int tcp_write_timeout(struct sock *sk)
tp->bytes_acked <= tp->rx_opt.mss_clamp) {
tcp_fastopen_cache_set(sk, 0, NULL, true, 0);
if (icsk->icsk_retransmits == net->ipv4.sysctl_tcp_retries1)
- NET_INC_STATS_BH(sock_net(sk),
- LINUX_MIB_TCPFASTOPENACTIVEFAIL);
+ NET_INC_STATS(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENACTIVEFAIL);
}
/* Black hole detection */
tcp_mtu_probing(icsk, sk);
@@ -209,6 +237,7 @@ static int tcp_write_timeout(struct sock *sk)
return 0;
}
+/* Called with BH disabled */
void tcp_delack_timer_handler(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -228,7 +257,7 @@ void tcp_delack_timer_handler(struct sock *sk)
if (!skb_queue_empty(&tp->ucopy.prequeue)) {
struct sk_buff *skb;
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSCHEDULERFAILED);
while ((skb = __skb_dequeue(&tp->ucopy.prequeue)) != NULL)
sk_backlog_rcv(sk, skb);
@@ -248,7 +277,7 @@ void tcp_delack_timer_handler(struct sock *sk)
icsk->icsk_ack.ato = TCP_ATO_MIN;
}
tcp_send_ack(sk);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
}
out:
@@ -256,6 +285,16 @@ out:
sk_mem_reclaim(sk);
}
+
+/**
+ * tcp_delack_timer() - The TCP delayed ACK timeout handler
+ * @data: Pointer to the current socket. (gets casted to struct sock *)
+ *
+ * This function gets (indirectly) called when the kernel timer for a TCP packet
+ * of this socket expires. Calls tcp_delack_timer_handler() to do the actual work.
+ *
+ * Returns: Nothing (void)
+ */
static void tcp_delack_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
@@ -265,7 +304,7 @@ static void tcp_delack_timer(unsigned long data)
tcp_delack_timer_handler(sk);
} else {
inet_csk(sk)->icsk_ack.blocked = 1;
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
+ __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
/* deleguate our work to tcp_release_cb() */
if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
sock_hold(sk);
@@ -345,14 +384,23 @@ static void tcp_fastopen_synack_timer(struct sock *sk)
*/
inet_rtx_syn_ack(sk, req);
req->num_timeout++;
+ icsk->icsk_retransmits++;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
}
-/*
- * The TCP retransmit timer.
- */
+/**
+ * tcp_retransmit_timer() - The TCP retransmit timeout handler
+ * @sk: Pointer to the current socket.
+ *
+ * This function gets called when the kernel timer for a TCP packet
+ * of this socket expires.
+ *
+ * It handles retransmission, timer adjustment and other necesarry measures.
+ *
+ * Returns: Nothing (void)
+ */
void tcp_retransmit_timer(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -404,7 +452,7 @@ void tcp_retransmit_timer(struct sock *sk)
goto out;
}
tcp_enter_loss(sk);
- tcp_retransmit_skb(sk, tcp_write_queue_head(sk));
+ tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1);
__sk_dst_reset(sk);
goto out_reset_timer;
}
@@ -431,12 +479,12 @@ void tcp_retransmit_timer(struct sock *sk)
} else {
mib_idx = LINUX_MIB_TCPTIMEOUTS;
}
- NET_INC_STATS_BH(sock_net(sk), mib_idx);
+ __NET_INC_STATS(sock_net(sk), mib_idx);
}
tcp_enter_loss(sk);
- if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) {
+ if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk), 1) > 0) {
/* Retransmission failed because of local congestion,
* do not backoff.
*/
@@ -493,6 +541,8 @@ out_reset_timer:
out:;
}
+/* Called with bottom-half processing disabled.
+ Called by tcp_write_timer() */
void tcp_write_timer_handler(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
@@ -537,7 +587,7 @@ static void tcp_write_timer(unsigned long data)
if (!sock_owned_by_user(sk)) {
tcp_write_timer_handler(sk);
} else {
- /* deleguate our work to tcp_release_cb() */
+ /* delegate our work to tcp_release_cb() */
if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
sock_hold(sk);
}
@@ -549,7 +599,7 @@ void tcp_syn_ack_timeout(const struct request_sock *req)
{
struct net *net = read_pnet(&inet_rsk(req)->ireq_net);
- NET_INC_STATS_BH(net, LINUX_MIB_TCPTIMEOUTS);
+ __NET_INC_STATS(net, LINUX_MIB_TCPTIMEOUTS);
}
EXPORT_SYMBOL(tcp_syn_ack_timeout);
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