[PATCH] sch_red: fix weighted average calculation

[Cyril Chemparathy]

This patch fixes an apparent bug in the running weighted average calculation
used in the RED algorithm.

Going by the described formula:
	   qavg = qavg*(1-W) + backlog*W
	=> qavg = qavg + (backlog - qavg) * W

... with W converted to a pre-calculated shift, this then becomes:
	qavg = qavg + (backlog - qavg) >> logW

... giving the modified expression introduced by this patch.

Signed-off-by: John Dowdal <jdowdal@xxxxxx>
---
 include/net/red.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/red.h b/include/net/red.h
index ef46058..05960a4 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -287,7 +287,7 @@ static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p
 	 *
 	 * --ANK (980924)
 	 */
-	return v->qavg + (backlog - (v->qavg >> p->Wlog));
+	return v->qavg + (backlog - v->qavg) >> p->Wlog;
 }
 
 static inline unsigned long red_calc_qavg(const struct red_parms *p,
-- 
1.7.9.5

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