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Diffstat (limited to 'net/ipv4/tcp_cong.c')
-rw-r--r--net/ipv4/tcp_cong.c68
1 files changed, 42 insertions, 26 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 5c8caf4..86b2653 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -12,6 +12,8 @@
#include <linux/list.h>
#include <net/tcp.h>
+int sysctl_tcp_max_ssthresh = 0;
+
static DEFINE_SPINLOCK(tcp_cong_list_lock);
static LIST_HEAD(tcp_cong_list);
@@ -77,18 +79,19 @@ void tcp_init_congestion_control(struct sock *sk)
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_congestion_ops *ca;
- if (icsk->icsk_ca_ops != &tcp_init_congestion_ops)
- return;
+ /* if no choice made yet assign the current value set as default */
+ if (icsk->icsk_ca_ops == &tcp_init_congestion_ops) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
+ if (try_module_get(ca->owner)) {
+ icsk->icsk_ca_ops = ca;
+ break;
+ }
- rcu_read_lock();
- list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
- if (try_module_get(ca->owner)) {
- icsk->icsk_ca_ops = ca;
- break;
+ /* fallback to next available */
}
-
+ rcu_read_unlock();
}
- rcu_read_unlock();
if (icsk->icsk_ca_ops->init)
icsk->icsk_ca_ops->init(sk);
@@ -123,7 +126,7 @@ int tcp_set_default_congestion_control(const char *name)
#endif
if (ca) {
- ca->non_restricted = 1; /* default is always allowed */
+ ca->flags |= TCP_CONG_NON_RESTRICTED; /* default is always allowed */
list_move(&ca->list, &tcp_cong_list);
ret = 0;
}
@@ -178,7 +181,7 @@ void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
*buf = '\0';
rcu_read_lock();
list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
- if (!ca->non_restricted)
+ if (!(ca->flags & TCP_CONG_NON_RESTRICTED))
continue;
offs += snprintf(buf + offs, maxlen - offs,
"%s%s",
@@ -209,16 +212,16 @@ int tcp_set_allowed_congestion_control(char *val)
}
}
- /* pass 2 clear */
+ /* pass 2 clear old values */
list_for_each_entry_rcu(ca, &tcp_cong_list, list)
- ca->non_restricted = 0;
+ ca->flags &= ~TCP_CONG_NON_RESTRICTED;
/* pass 3 mark as allowed */
while ((name = strsep(&val, " ")) && *name) {
ca = tcp_ca_find(name);
WARN_ON(!ca);
if (ca)
- ca->non_restricted = 1;
+ ca->flags |= TCP_CONG_NON_RESTRICTED;
}
out:
spin_unlock(&tcp_cong_list_lock);
@@ -236,6 +239,7 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
rcu_read_lock();
ca = tcp_ca_find(name);
+
/* no change asking for existing value */
if (ca == icsk->icsk_ca_ops)
goto out;
@@ -252,7 +256,7 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
if (!ca)
err = -ENOENT;
- else if (!(ca->non_restricted || capable(CAP_NET_ADMIN)))
+ else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || capable(CAP_NET_ADMIN)))
err = -EPERM;
else if (!try_module_get(ca->owner))
@@ -261,7 +265,8 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
else {
tcp_cleanup_congestion_control(sk);
icsk->icsk_ca_ops = ca;
- if (icsk->icsk_ca_ops->init)
+
+ if (sk->sk_state != TCP_CLOSE && icsk->icsk_ca_ops->init)
icsk->icsk_ca_ops->init(sk);
}
out:
@@ -271,10 +276,13 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
/*
- * Linear increase during slow start
+ * Slow start (exponential increase) with
+ * RFC3742 Limited Slow Start (fast linear increase) support.
*/
void tcp_slow_start(struct tcp_sock *tp)
{
+ int cnt = 0;
+
if (sysctl_tcp_abc) {
/* RFC3465: Slow Start
* TCP sender SHOULD increase cwnd by the number of
@@ -283,17 +291,25 @@ void tcp_slow_start(struct tcp_sock *tp)
*/
if (tp->bytes_acked < tp->mss_cache)
return;
-
- /* We MAY increase by 2 if discovered delayed ack */
- if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) {
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- }
}
+
+ if (sysctl_tcp_max_ssthresh > 0 &&
+ tp->snd_cwnd > sysctl_tcp_max_ssthresh)
+ cnt += sysctl_tcp_max_ssthresh>>1;
+ else
+ cnt += tp->snd_cwnd;
+
+ /* RFC3465: We MAY increase by 2 if discovered delayed ack */
+ if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
+ cnt <<= 1;
tp->bytes_acked = 0;
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
+ tp->snd_cwnd_cnt += cnt;
+ while (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ tp->snd_cwnd_cnt -= tp->snd_cwnd;
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ }
}
EXPORT_SYMBOL_GPL(tcp_slow_start);
@@ -355,8 +371,8 @@ u32 tcp_reno_min_cwnd(const struct sock *sk)
EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
struct tcp_congestion_ops tcp_reno = {
+ .flags = TCP_CONG_NON_RESTRICTED,
.name = "reno",
- .non_restricted = 1,
.owner = THIS_MODULE,
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
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