[34-longterm 030/247] ath9k: Fix bug in delimiter padding computation

Paul Gortmaker
2011-06-23T17:22:48Z

From: Vasanthakumar Thiagarajan <vasanth@atheros.com>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
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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@openwrt.org>
Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/net/wireless/ath/ath9k/ath9k.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 83c7ea4..7f36731 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -172,8 +172,8 @@ void ath_descdma_cleanup(struct ath_softc *sc, struct ath_descdma *dd,

/* 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))
--
1.7.4.4