Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b9ce204f0a265f819d10c943a607746abb62f245
Commit:     b9ce204f0a265f819d10c943a607746abb62f245
Parent:     22b1a9203ea634ac0ee5240e021613da3328275f
Author:     Ilpo Järvinen <[EMAIL PROTECTED]>
AuthorDate: Fri Jun 15 15:08:43 2007 -0700
Committer:  David S. Miller <[EMAIL PROTECTED]>
CommitDate: Fri Jun 15 15:08:43 2007 -0700

    [TCP]: Congestion control API RTT sampling fix
    
    Commit 164891aadf1721fca4dce473bb0e0998181537c6 broke RTT
    sampling of congestion control modules. Inaccurate timestamps
    could be fed to them without providing any way for them to
    identify such cases. Previously RTT sampler was called only if
    FLAG_RETRANS_DATA_ACKED was not set filtering inaccurate
    timestamps nicely. In addition, the new behavior could give an
    invalid timestamp (zero) to RTT sampler if only skbs with
    TCPCB_RETRANS were ACKed. This solves both problems.
    
    Signed-off-by: Ilpo Järvinen <[EMAIL PROTECTED]>
    Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
 include/linux/ktime.h   |   12 ++++++++++++
 include/linux/skbuff.h  |    4 ++++
 net/ipv4/tcp_illinois.c |    3 +++
 net/ipv4/tcp_input.c    |    6 +++++-
 net/ipv4/tcp_lp.c       |    3 ++-
 net/ipv4/tcp_vegas.c    |    3 +++
 net/ipv4/tcp_veno.c     |    3 +++
 7 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index c762954..2b139f6 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -261,6 +261,18 @@ static inline s64 ktime_to_ns(const ktime_t kt)
 
 #endif
 
+/**
+ * ktime_equal - Compares two ktime_t variables to see if they are equal
+ * @cmp1:      comparable1
+ * @cmp2:      comparable2
+ *
+ * Compare two ktime_t variables, returns 1 if equal
+ */
+static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
+{
+       return cmp1.tv64 == cmp2.tv64;
+}
+
 static inline s64 ktime_to_us(const ktime_t kt)
 {
        struct timeval tv = ktime_to_timeval(kt);
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index e7367c7..6f0b2f7 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1579,6 +1579,10 @@ static inline ktime_t net_timedelta(ktime_t t)
        return ktime_sub(ktime_get_real(), t);
 }
 
+static inline ktime_t net_invalid_timestamp(void)
+{
+       return ktime_set(0, 0);
+}
 
 extern __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
 extern __sum16 __skb_checksum_complete(struct sk_buff *skb);
diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 4adc47c..b2b2256 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -90,6 +90,9 @@ static void tcp_illinois_acked(struct sock *sk, u32 
pkts_acked, ktime_t last)
 
        ca->acked = pkts_acked;
 
+       if (ktime_equal(last, net_invalid_timestamp()))
+               return;
+
        rtt = ktime_to_us(net_timedelta(last));
 
        /* ignore bogus values, this prevents wraparound in alpha math */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d6d0f9b..aaf6f66 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2409,7 +2409,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 
*seq_rtt_p)
        int acked = 0;
        int prior_packets = tp->packets_out;
        __s32 seq_rtt = -1;
-       ktime_t last_ackt = ktime_set(0,0);
+       ktime_t last_ackt = net_invalid_timestamp();
 
        while ((skb = tcp_write_queue_head(sk)) &&
               skb != tcp_send_head(sk)) {
@@ -2487,6 +2487,10 @@ static int tcp_clean_rtx_queue(struct sock *sk, __s32 
*seq_rtt_p)
                tcp_ack_update_rtt(sk, acked, seq_rtt);
                tcp_ack_packets_out(sk);
 
+               /* Is the ACK triggering packet unambiguous? */
+               if (acked & FLAG_RETRANS_DATA_ACKED)
+                       last_ackt = net_invalid_timestamp();
+
                if (ca_ops->pkts_acked)
                        ca_ops->pkts_acked(sk, pkts_acked, last_ackt);
        }
diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c
index 43294ad..e49836c 100644
--- a/net/ipv4/tcp_lp.c
+++ b/net/ipv4/tcp_lp.c
@@ -266,7 +266,8 @@ static void tcp_lp_pkts_acked(struct sock *sk, u32 
num_acked, ktime_t last)
        struct tcp_sock *tp = tcp_sk(sk);
        struct lp *lp = inet_csk_ca(sk);
 
-       tcp_lp_rtt_sample(sk,  ktime_to_us(net_timedelta(last)));
+       if (!ktime_equal(last, net_invalid_timestamp()))
+               tcp_lp_rtt_sample(sk,  ktime_to_us(net_timedelta(last)));
 
        /* calc inference */
        if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 73e19cf..e218a51 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -117,6 +117,9 @@ void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, ktime_t 
last)
        struct vegas *vegas = inet_csk_ca(sk);
        u32 vrtt;
 
+       if (ktime_equal(last, net_invalid_timestamp()))
+               return;
+
        /* Never allow zero rtt or baseRTT */
        vrtt = ktime_to_us(net_timedelta(last)) + 1;
 
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index 9edb340..ec854cc 100644
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -74,6 +74,9 @@ static void tcp_veno_pkts_acked(struct sock *sk, u32 cnt, 
ktime_t last)
        struct veno *veno = inet_csk_ca(sk);
        u32 vrtt;
 
+       if (ktime_equal(last, net_invalid_timestamp()))
+               return;
+
        /* Never allow zero rtt or baseRTT */
        vrtt = ktime_to_us(net_timedelta(last)) + 1;
 
-
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