[PATCH] [36/275] ath9k: Fix bug in delimiter padding computation

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Vasanthakumar Thiagarajan <vasanth@xxxxxxxxxxx>

commit 39ec2997c374b528cdbf65099b6d6b8593a67f7f upstream.

There is a roundng error in delimiter padding computation
which causes severe throughput drop with some of AR9003.

signed-off-by: Felix Fietkau <nbd@xxxxxxxxxxx>
Signed-off-by: Vasanthakumar Thiagarajan <vasanth@xxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 drivers/net/wireless/ath/ath9k/ath9k.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.35.y/drivers/net/wireless/ath/ath9k/ath9k.h
===================================================================
--- linux-2.6.35.y.orig/drivers/net/wireless/ath/ath9k/ath9k.h	2011-03-29 22:51:54.545327490 -0700
+++ linux-2.6.35.y/drivers/net/wireless/ath/ath9k/ath9k.h	2011-03-29 23:02:58.936327387 -0700
@@ -174,8 +174,8 @@
 
 /* returns delimiter padding required given the packet length */
 #define ATH_AGGR_GET_NDELIM(_len)					\
-	(((((_len) + ATH_AGGR_DELIM_SZ) < ATH_AGGR_MINPLEN) ?           \
-	  (ATH_AGGR_MINPLEN - (_len) - ATH_AGGR_DELIM_SZ) : 0) >> 2)
+       (((_len) >= ATH_AGGR_MINPLEN) ? 0 :                             \
+        DIV_ROUND_UP(ATH_AGGR_MINPLEN - (_len), ATH_AGGR_DELIM_SZ))
 
 #define BAW_WITHIN(_start, _bawsz, _seqno) \
 	((((_seqno) - (_start)) & 4095) < (_bawsz))
--
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