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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2010-08-29 19:23:12 +0000
committerDavid S. Miller <davem@davemloft.net>2010-08-30 13:45:26 -0700
commit22b71c8f4f3db8df92f5e7b081c265bc56c0bd2f (patch)
treeb913f63369b09ad703ed52a42b367455785ef3af /include/net/tcp.h
parentd26eeb07fd02de31848b59d19687daff0e93532f (diff)
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tcp/dccp: Consolidate common code for RFC 3390 conversion
This patch consolidates initial-window code common to TCP and CCID-2: * TCP uses RFC 3390 in a packet-oriented manner (tcp_input.c) and * CCID-2 uses RFC 3390 in packet-oriented manner (RFC 4341). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/tcp.h')
-rw-r--r--include/net/tcp.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index df6a2eb20193..a64022199b62 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -779,6 +779,21 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
/* Use define here intentionally to get WARN_ON location shown at the caller */
#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
+/*
+ * Convert RFC 3390 larger initial window into an equivalent number of packets.
+ *
+ * John Heffner states:
+ *
+ * The RFC specifies a window of no more than 4380 bytes
+ * unless 2*MSS > 4380. Reading the pseudocode in the RFC
+ * is a bit misleading because they use a clamp at 4380 bytes
+ * rather than a multiplier in the relevant range.
+ */
+static inline u32 rfc3390_bytes_to_packets(const u32 smss)
+{
+ return smss <= 1095 ? 4 : (smss > 1460 ? 2 : 3);
+}
+
extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);