From 4389dded7767d24290463f2a8302ba3253ebdd56 Mon Sep 17 00:00:00 2001 From: Adam Langley Date: Sat, 19 Jul 2008 00:07:02 -0700 Subject: [PATCH] tcp: Remove redundant checks when setting eff_sacks Remove redundant checks when setting eff_sacks and make the number of SACKs a compile time constant. Now that the options code knows how many SACK blocks can fit in the header, we don't need to have the SACK code guessing at it. Signed-off-by: Adam Langley Signed-off-by: David S. Miller --- include/linux/tcp.h | 6 ++++++ net/ipv4/tcp_input.c | 25 ++++++++++--------------- 2 files changed, 16 insertions(+), 15 deletions(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 07e79bdb9cdf..2e2557388e36 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -224,6 +224,12 @@ struct tcp_options_received { u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ }; +/* This is the max number of SACKS that we'll generate and process. It's safe + * to increse this, although since: + * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) + * only four options will fit in a standard TCP header */ +#define TCP_NUM_SACKS 4 + struct tcp_request_sock { struct inet_request_sock req; #ifdef CONFIG_TCP_MD5SIG diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 88810bc01370..1f5e6049883e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1423,10 +1423,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, unsigned char *ptr = (skb_transport_header(ack_skb) + TCP_SKB_CB(ack_skb)->sacked); struct tcp_sack_block_wire *sp_wire = (struct tcp_sack_block_wire *)(ptr+2); - struct tcp_sack_block sp[4]; + struct tcp_sack_block sp[TCP_NUM_SACKS]; struct tcp_sack_block *cache; struct sk_buff *skb; - int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE) >> 3; + int num_sacks = min(TCP_NUM_SACKS, (ptr[1] - TCPOLEN_SACK_BASE) >> 3); int used_sacks; int reord = tp->packets_out; int flag = 0; @@ -3735,8 +3735,7 @@ static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq) tp->rx_opt.dsack = 1; tp->duplicate_sack[0].start_seq = seq; tp->duplicate_sack[0].end_seq = end_seq; - tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + 1, - 4 - tp->rx_opt.tstamp_ok); + tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + 1; } } @@ -3791,9 +3790,8 @@ static void tcp_sack_maybe_coalesce(struct tcp_sock *tp) * Decrease num_sacks. */ tp->rx_opt.num_sacks--; - tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + - tp->rx_opt.dsack, - 4 - tp->rx_opt.tstamp_ok); + tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + + tp->rx_opt.dsack; for (i = this_sack; i < tp->rx_opt.num_sacks; i++) sp[i] = sp[i + 1]; continue; @@ -3843,7 +3841,7 @@ static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq) * * If the sack array is full, forget about the last one. */ - if (this_sack >= 4) { + if (this_sack >= TCP_NUM_SACKS) { this_sack--; tp->rx_opt.num_sacks--; sp--; @@ -3856,8 +3854,7 @@ new_sack: sp->start_seq = seq; sp->end_seq = end_seq; tp->rx_opt.num_sacks++; - tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, - 4 - tp->rx_opt.tstamp_ok); + tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; } /* RCV.NXT advances, some SACKs should be eaten. */ @@ -3894,9 +3891,8 @@ static void tcp_sack_remove(struct tcp_sock *tp) } if (num_sacks != tp->rx_opt.num_sacks) { tp->rx_opt.num_sacks = num_sacks; - tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + - tp->rx_opt.dsack, - 4 - tp->rx_opt.tstamp_ok); + tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks + + tp->rx_opt.dsack; } } @@ -3975,8 +3971,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) if (tp->rx_opt.dsack) { tp->rx_opt.dsack = 0; - tp->rx_opt.eff_sacks = min_t(unsigned int, tp->rx_opt.num_sacks, - 4 - tp->rx_opt.tstamp_ok); + tp->rx_opt.eff_sacks = tp->rx_opt.num_sacks; } /* Queue data for delivery to the user. -- 2.20.1