Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

Pull networking updates from David Miller:

 1) Unified UDP encapsulation offload methods for drivers, from
    Alexander Duyck.

 2) Make DSA binding more sane, from Andrew Lunn.

 3) Support QCA9888 chips in ath10k, from Anilkumar Kolli.

 4) Several workqueue usage cleanups, from Bhaktipriya Shridhar.

 5) Add XDP (eXpress Data Path), essentially running BPF programs on RX
    packets as soon as the device sees them, with the option to mirror
    the packet on TX via the same interface.  From Brenden Blanco and
    others.

 6) Allow qdisc/class stats dumps to run lockless, from Eric Dumazet.

 7) Add VLAN support to b53 and bcm_sf2, from Florian Fainelli.

 8) Simplify netlink conntrack entry layout, from Florian Westphal.

 9) Add ipv4 forwarding support to mlxsw spectrum driver, from Ido
    Schimmel, Yotam Gigi, and Jiri Pirko.

10) Add SKB array infrastructure and convert tun and macvtap over to it.
    From Michael S Tsirkin and Jason Wang.

11) Support qdisc packet injection in pktgen, from John Fastabend.

12) Add neighbour monitoring framework to TIPC, from Jon Paul Maloy.

13) Add NV congestion control support to TCP, from Lawrence Brakmo.

14) Add GSO support to SCTP, from Marcelo Ricardo Leitner.

15) Allow GRO and RPS to function on macsec devices, from Paolo Abeni.

16) Support MPLS over IPV4, from Simon Horman.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits)
  xgene: Fix build warning with ACPI disabled.
  be2net: perform temperature query in adapter regardless of its interface state
  l2tp: Correctly return -EBADF from pppol2tp_getname.
  net/mlx5_core/health: Remove deprecated create_singlethread_workqueue
  net: ipmr/ip6mr: update lastuse on entry change
  macsec: ensure rx_sa is set when validation is disabled
  tipc: dump monitor attributes
  tipc: add a function to get the bearer name
  tipc: get monitor threshold for the cluster
  tipc: make cluster size threshold for monitoring configurable
  tipc: introduce constants for tipc address validation
  net: neigh: disallow transition to NUD_STALE if lladdr is unchanged in neigh_update()
  MAINTAINERS: xgene: Add driver and documentation path
  Documentation: dtb: xgene: Add MDIO node
  dtb: xgene: Add MDIO node
  drivers: net: xgene: ethtool: Use phy_ethtool_gset and sset
  drivers: net: xgene: Use exported functions
  drivers: net: xgene: Enable MDIO driver
  drivers: net: xgene: Add backward compatibility
  drivers: net: phy: xgene: Add MDIO driver
  ...

1 files changed, 64 insertions, 17 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index debdd8b33e69..d84930b2dd95 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -24,6 +24,13 @@
 
 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;
@@ -33,16 +40,21 @@ static void tcp_write_err(struct sock *sk)
 	__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)
 {
@@ -74,7 +86,11 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
 	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,
@@ -257,6 +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;
@@ -350,10 +388,18 @@ static void tcp_fastopen_synack_timer(struct sock *sk)
 			  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);
@@ -494,7 +540,8 @@ out_reset_timer:
 out:;
 }
 
-/* Called with BH disabled */
+/* 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);
@@ -539,7 +586,7 @@ 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);
 	}