android_kernel_xiaomi_sm8350/net/dccp/timer.c
Eric Dumazet b6c6712a42 net: sk_dst_cache RCUification
With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
work.

sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)

This rwlock is readlocked for a very small amount of time, and dst
entries are already freed after RCU grace period. This calls for RCU
again :)

This patch converts sk_dst_lock to a spinlock, and use RCU for readers.

__sk_dst_get() is supposed to be called with rcu_read_lock() or if
socket locked by user, so use appropriate rcu_dereference_check()
condition (rcu_read_lock_held() || sock_owned_by_user(sk))

This patch avoids two atomic ops per tx packet on UDP connected sockets,
for example, and permits sk_dst_lock to be much less dirtied.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-04-13 01:41:33 -07:00

290 lines
7.4 KiB
C

/*
* net/dccp/timer.c
*
* An implementation of the DCCP protocol
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/dccp.h>
#include <linux/skbuff.h>
#include "dccp.h"
/* sysctl variables governing numbers of retransmission attempts */
int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
static void dccp_write_err(struct sock *sk)
{
sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
sk->sk_error_report(sk);
dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
dccp_done(sk);
DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
}
/* A write timeout has occurred. Process the after effects. */
static int dccp_write_timeout(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
int retry_until;
if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
if (icsk->icsk_retransmits != 0)
dst_negative_advice(sk);
retry_until = icsk->icsk_syn_retries ?
: sysctl_dccp_request_retries;
} else {
if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
/* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
black hole detection. :-(
It is place to make it. It is not made. I do not want
to make it. It is disguisting. It does not work in any
case. Let me to cite the same draft, which requires for
us to implement this:
"The one security concern raised by this memo is that ICMP black holes
are often caused by over-zealous security administrators who block
all ICMP messages. It is vitally important that those who design and
deploy security systems understand the impact of strict filtering on
upper-layer protocols. The safest web site in the world is worthless
if most TCP implementations cannot transfer data from it. It would
be far nicer to have all of the black holes fixed rather than fixing
all of the TCP implementations."
Golden words :-).
*/
dst_negative_advice(sk);
}
retry_until = sysctl_dccp_retries2;
/*
* FIXME: see tcp_write_timout and tcp_out_of_resources
*/
}
if (icsk->icsk_retransmits >= retry_until) {
/* Has it gone just too far? */
dccp_write_err(sk);
return 1;
}
return 0;
}
/*
* The DCCP retransmit timer.
*/
static void dccp_retransmit_timer(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
/*
* More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
* sent, no need to retransmit, this sock is dead.
*/
if (dccp_write_timeout(sk))
return;
/*
* We want to know the number of packets retransmitted, not the
* total number of retransmissions of clones of original packets.
*/
if (icsk->icsk_retransmits == 0)
DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
if (dccp_retransmit_skb(sk) != 0) {
/*
* Retransmission failed because of local congestion,
* do not backoff.
*/
if (--icsk->icsk_retransmits == 0)
icsk->icsk_retransmits = 1;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
min(icsk->icsk_rto,
TCP_RESOURCE_PROBE_INTERVAL),
DCCP_RTO_MAX);
return;
}
icsk->icsk_backoff++;
icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
DCCP_RTO_MAX);
if (icsk->icsk_retransmits > sysctl_dccp_retries1)
__sk_dst_reset(sk);
}
static void dccp_write_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct inet_connection_sock *icsk = inet_csk(sk);
int event = 0;
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later */
sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
jiffies + (HZ / 20));
goto out;
}
if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
goto out;
if (time_after(icsk->icsk_timeout, jiffies)) {
sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
icsk->icsk_timeout);
goto out;
}
event = icsk->icsk_pending;
icsk->icsk_pending = 0;
switch (event) {
case ICSK_TIME_RETRANS:
dccp_retransmit_timer(sk);
break;
}
out:
bh_unlock_sock(sk);
sock_put(sk);
}
/*
* Timer for listening sockets
*/
static void dccp_response_timer(struct sock *sk)
{
inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
DCCP_RTO_MAX);
}
static void dccp_keepalive_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
/* Only process if socket is not in use. */
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
inet_csk_reset_keepalive_timer(sk, HZ / 20);
goto out;
}
if (sk->sk_state == DCCP_LISTEN) {
dccp_response_timer(sk);
goto out;
}
out:
bh_unlock_sock(sk);
sock_put(sk);
}
/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
static void dccp_delack_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct inet_connection_sock *icsk = inet_csk(sk);
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
icsk->icsk_ack.blocked = 1;
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
sk_reset_timer(sk, &icsk->icsk_delack_timer,
jiffies + TCP_DELACK_MIN);
goto out;
}
if (sk->sk_state == DCCP_CLOSED ||
!(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
goto out;
if (time_after(icsk->icsk_ack.timeout, jiffies)) {
sk_reset_timer(sk, &icsk->icsk_delack_timer,
icsk->icsk_ack.timeout);
goto out;
}
icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
if (inet_csk_ack_scheduled(sk)) {
if (!icsk->icsk_ack.pingpong) {
/* Delayed ACK missed: inflate ATO. */
icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
icsk->icsk_rto);
} else {
/* Delayed ACK missed: leave pingpong mode and
* deflate ATO.
*/
icsk->icsk_ack.pingpong = 0;
icsk->icsk_ack.ato = TCP_ATO_MIN;
}
dccp_send_ack(sk);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKS);
}
out:
bh_unlock_sock(sk);
sock_put(sk);
}
/* Transmit-delay timer: used by the CCIDs to delay actual send time */
static void dccp_write_xmit_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct dccp_sock *dp = dccp_sk(sk);
bh_lock_sock(sk);
if (sock_owned_by_user(sk))
sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
else
dccp_write_xmit(sk, 0);
bh_unlock_sock(sk);
sock_put(sk);
}
static void dccp_init_write_xmit_timer(struct sock *sk)
{
struct dccp_sock *dp = dccp_sk(sk);
setup_timer(&dp->dccps_xmit_timer, dccp_write_xmit_timer,
(unsigned long)sk);
}
void dccp_init_xmit_timers(struct sock *sk)
{
dccp_init_write_xmit_timer(sk);
inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
&dccp_keepalive_timer);
}
static ktime_t dccp_timestamp_seed;
/**
* dccp_timestamp - 10s of microseconds time source
* Returns the number of 10s of microseconds since loading DCCP. This is native
* DCCP time difference format (RFC 4340, sec. 13).
* Please note: This will wrap around about circa every 11.9 hours.
*/
u32 dccp_timestamp(void)
{
s64 delta = ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
do_div(delta, 10);
return delta;
}
EXPORT_SYMBOL_GPL(dccp_timestamp);
void __init dccp_timestamping_init(void)
{
dccp_timestamp_seed = ktime_get_real();
}