Skip to content

Commit

Permalink
tcp: refactor undo functions
Browse files Browse the repository at this point in the history 
Refactor and relocate various functions or variables to prepare the
undo fix.  Remove some unused function arguments. Rename tcp_undo_cwr
to tcp_undo_cwnd_reduction to be consistent with the rest of
CWR related function names.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Yuchung Cheng authored and David S. Miller committed May 31, 2013
1 parent 6804973 commit 6a63df4
Showing 1 changed file with 50 additions and 47 deletions.
97 changes: 50 additions & 47 deletions net/ipv4/tcp_input.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2243,10 +2243,23 @@ static void DBGUNDO(struct sock *sk, const char *msg)
#define DBGUNDO(x...) do { } while (0)
#endif

static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
static void tcp_undo_cwnd_reduction(struct sock *sk, const bool undo_ssthresh,
bool unmark_loss)
{
struct tcp_sock *tp = tcp_sk(sk);

if (unmark_loss) {
struct sk_buff *skb;

tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
}
tp->lost_out = 0;
tcp_clear_all_retrans_hints(tp);
}

if (tp->prior_ssthresh) {
const struct inet_connection_sock *icsk = inet_csk(sk);

Expand All @@ -2263,6 +2276,9 @@ static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
}
tp->snd_cwnd_stamp = tcp_time_stamp;

if (undo_ssthresh)
tp->undo_marker = 0;
}

static inline bool tcp_may_undo(const struct tcp_sock *tp)
Expand All @@ -2282,14 +2298,13 @@ static bool tcp_try_undo_recovery(struct sock *sk)
* or our original transmission succeeded.
*/
DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
tcp_undo_cwr(sk, true);
tcp_undo_cwnd_reduction(sk, true, false);
if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
mib_idx = LINUX_MIB_TCPLOSSUNDO;
else
mib_idx = LINUX_MIB_TCPFULLUNDO;

NET_INC_STATS_BH(sock_net(sk), mib_idx);
tp->undo_marker = 0;
}
if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
/* Hold old state until something *above* high_seq
Expand All @@ -2309,8 +2324,7 @@ static void tcp_try_undo_dsack(struct sock *sk)

if (tp->undo_marker && !tp->undo_retrans) {
DBGUNDO(sk, "D-SACK");
tcp_undo_cwr(sk, true);
tp->undo_marker = 0;
tcp_undo_cwnd_reduction(sk, true, false);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
}
}
Expand Down Expand Up @@ -2344,60 +2358,20 @@ static bool tcp_any_retrans_done(const struct sock *sk)
return false;
}

/* Undo during fast recovery after partial ACK. */

static int tcp_try_undo_partial(struct sock *sk, int acked)
{
struct tcp_sock *tp = tcp_sk(sk);
/* Partial ACK arrived. Force Hoe's retransmit. */
int failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);

if (tcp_may_undo(tp)) {
/* Plain luck! Hole if filled with delayed
* packet, rather than with a retransmit.
*/
if (!tcp_any_retrans_done(sk))
tp->retrans_stamp = 0;

tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);

DBGUNDO(sk, "Hoe");
tcp_undo_cwr(sk, false);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);

/* So... Do not make Hoe's retransmit yet.
* If the first packet was delayed, the rest
* ones are most probably delayed as well.
*/
failed = 0;
}
return failed;
}

/* Undo during loss recovery after partial ACK or using F-RTO. */
static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
{
struct tcp_sock *tp = tcp_sk(sk);

if (frto_undo || tcp_may_undo(tp)) {
struct sk_buff *skb;
tcp_for_write_queue(skb, sk) {
if (skb == tcp_send_head(sk))
break;
TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
}

tcp_clear_all_retrans_hints(tp);
tcp_undo_cwnd_reduction(sk, true, true);

DBGUNDO(sk, "partial loss");
tp->lost_out = 0;
tcp_undo_cwr(sk, true);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
if (frto_undo)
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPSPURIOUSRTOS);
inet_csk(sk)->icsk_retransmits = 0;
tp->undo_marker = 0;
if (frto_undo || tcp_is_sack(tp))
tcp_set_ca_state(sk, TCP_CA_Open);
return true;
Expand Down Expand Up @@ -2669,6 +2643,35 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
tcp_xmit_retransmit_queue(sk);
}

/* Undo during fast recovery after partial ACK. */
static bool tcp_try_undo_partial(struct sock *sk, int acked)
{
struct tcp_sock *tp = tcp_sk(sk);
/* Partial ACK arrived. Force Hoe's retransmit. */
bool failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);

if (tcp_may_undo(tp)) {
/* Plain luck! Hole if filled with delayed
* packet, rather than with a retransmit.
*/
if (!tcp_any_retrans_done(sk))
tp->retrans_stamp = 0;

tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);

DBGUNDO(sk, "Hoe");
tcp_undo_cwnd_reduction(sk, false, false);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);

/* So... Do not make Hoe's retransmit yet.
* If the first packet was delayed, the rest
* ones are most probably delayed as well.
*/
failed = false;
}
return failed;
}

/* Process an event, which can update packets-in-flight not trivially.
* Main goal of this function is to calculate new estimate for left_out,
* taking into account both packets sitting in receiver's buffer and
Expand All @@ -2686,7 +2689,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
(tcp_fackets_out(tp) > tp->reordering));
int fast_rexmit = 0;

Expand Down

0 comments on commit 6a63df4

Please sign in to comment.