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Merge branch 'tcp-redundant-checks'
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Soheil Hassas Yeganeh says:

====================
tcp: simplify ack tx timestamps

v2:
- Fully remove SKBTX_ACK_TSTAMP, as suggested by Willem de Bruijn.

This patch series aims at removing redundant checks and fields
for ack timestamps for TCP.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Apr 28, 2016
2 parents ba7863f + 0a2cf20 commit 2a9e843
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Showing 5 changed files with 17 additions and 19 deletions.
6 changes: 1 addition & 5 deletions include/linux/skbuff.h
Original file line number Diff line number Diff line change
Expand Up @@ -382,14 +382,10 @@ enum {

/* generate software time stamp when entering packet scheduling */
SKBTX_SCHED_TSTAMP = 1 << 6,

/* generate software timestamp on peer data acknowledgment */
SKBTX_ACK_TSTAMP = 1 << 7,
};

#define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
SKBTX_SCHED_TSTAMP | \
SKBTX_ACK_TSTAMP)
SKBTX_SCHED_TSTAMP)
#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)

/*
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7 changes: 4 additions & 3 deletions net/ipv4/tcp.c
Original file line number Diff line number Diff line change
Expand Up @@ -430,14 +430,15 @@ EXPORT_SYMBOL(tcp_init_sock);

static void tcp_tx_timestamp(struct sock *sk, u16 tsflags, struct sk_buff *skb)
{
if (sk->sk_tsflags || tsflags) {
if (tsflags) {
struct skb_shared_info *shinfo = skb_shinfo(skb);
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);

sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
if (shinfo->tx_flags & SKBTX_ANY_TSTAMP)
if (tsflags & SOF_TIMESTAMPING_TX_ACK)
tcb->txstamp_ack = 1;
if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
tcb->txstamp_ack = !!(shinfo->tx_flags & SKBTX_ACK_TSTAMP);
}
}

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3 changes: 1 addition & 2 deletions net/ipv4/tcp_input.c
Original file line number Diff line number Diff line change
Expand Up @@ -3087,8 +3087,7 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
return;

shinfo = skb_shinfo(skb);
if ((shinfo->tx_flags & SKBTX_ACK_TSTAMP) &&
!before(shinfo->tskey, prior_snd_una) &&
if (!before(shinfo->tskey, prior_snd_una) &&
before(shinfo->tskey, tcp_sk(sk)->snd_una))
__skb_tstamp_tx(skb, NULL, sk, SCM_TSTAMP_ACK);
}
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17 changes: 11 additions & 6 deletions net/ipv4/tcp_output.c
Original file line number Diff line number Diff line change
Expand Up @@ -1111,11 +1111,17 @@ static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int de
tcp_verify_left_out(tp);
}

static bool tcp_has_tx_tstamp(const struct sk_buff *skb)
{
return TCP_SKB_CB(skb)->txstamp_ack ||
(skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP);
}

static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);

if (unlikely(shinfo->tx_flags & SKBTX_ANY_TSTAMP) &&
if (unlikely(tcp_has_tx_tstamp(skb)) &&
!before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) {
struct skb_shared_info *shinfo2 = skb_shinfo(skb2);
u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP;
Expand Down Expand Up @@ -2446,13 +2452,12 @@ u32 __tcp_select_window(struct sock *sk)
void tcp_skb_collapse_tstamp(struct sk_buff *skb,
const struct sk_buff *next_skb)
{
const struct skb_shared_info *next_shinfo = skb_shinfo(next_skb);
u8 tsflags = next_shinfo->tx_flags & SKBTX_ANY_TSTAMP;

if (unlikely(tsflags)) {
if (unlikely(tcp_has_tx_tstamp(next_skb))) {
const struct skb_shared_info *next_shinfo =
skb_shinfo(next_skb);
struct skb_shared_info *shinfo = skb_shinfo(skb);

shinfo->tx_flags |= tsflags;
shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP;
shinfo->tskey = next_shinfo->tskey;
TCP_SKB_CB(skb)->txstamp_ack |=
TCP_SKB_CB(next_skb)->txstamp_ack;
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3 changes: 0 additions & 3 deletions net/socket.c
Original file line number Diff line number Diff line change
Expand Up @@ -600,9 +600,6 @@ void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags)
if (tsflags & SOF_TIMESTAMPING_TX_SCHED)
flags |= SKBTX_SCHED_TSTAMP;

if (tsflags & SOF_TIMESTAMPING_TX_ACK)
flags |= SKBTX_ACK_TSTAMP;

*tx_flags = flags;
}
EXPORT_SYMBOL(__sock_tx_timestamp);
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