[NET_SCHED]: Making rate table lookups more flexible.

This is done in order to, add support to changing the rate table to
use the upper-boundry L2T (length to time) value. Currently we use the
lower-boundry, which result in under-estimating the actual bandwidth
usage.

Extend the tc_ratespec struct, with two parameters: 1) "cell_align"
that allow adjusting the alignment of the rate table. 2) "overhead"
that allow adding a packet overhead before the lookup.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
index 268c51599eb8..919af93b7059 100644
--- a/include/linux/pkt_sched.h
+++ b/include/linux/pkt_sched.h
@@ -77,8 +77,8 @@ struct tc_ratespec
 {
         unsigned char   cell_log;
         unsigned char   __reserved;
-        unsigned short  feature;
-        short           addend;
+        unsigned short  overhead;
+        short           cell_align;
         unsigned short  mpu;
         __u32           rate;
 };
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 4ebd615bd013..a02ec9e5fea5 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -307,7 +307,9 @@ drop:
  */
 static inline u32 qdisc_l2t(struct qdisc_rate_table* rtab, unsigned int pktlen)
 {
-        int slot = pktlen;
+        int slot = pktlen + rtab->rate.cell_align + rtab->rate.overhead;
+        if (slot < 0)
+                slot = 0;
         slot >>= rtab->rate.cell_log;
         if (slot > 255)
                 return (rtab->data[255]*(slot >> 8) + rtab->data[slot & 0xFF]);