linux-kernel - [PATCH 3.12 079/212] ath5k: fix regression in tx status processing

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Message-Id: <20131202191256.584735994@linuxfoundation.org>
Date:	Mon,  2 Dec 2013 11:14:30 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Thomas Huehn <thomas@....t-labs.tu-berlin.de>,
	Benjamin Vahl <bvahl@....t-labs.tu-berlin.de>,
	Ben West <ben@...asabi.net>, Felix Fietkau <nbd@...nwrt.org>,
	"John W. Linville" <linville@...driver.com>
Subject: [PATCH 3.12 079/212] ath5k: fix regression in tx status processing

3.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <nbd@...nwrt.org>

commit 7ede612fd615abcda0cc30e5bef2a70f4cf4f75c upstream.

The regression was introduced in the following commit:

0967e01e8e713ed2982fb4eba8ba13794e9a6e89
"ath5k: make use of the new rate control API"

ath5k_tx_frame_completed saves the intended per-rate retry counts before
they are cleared by ieee80211_tx_info_clear_status, however at this
point the information in info->status.rates is incomplete.

This causes significant throughput degradation and excessive packet loss
on links where high bit rates don't work properly.

Move the copy from bf->rates a few lines up to ensure that the saved
retry counts are updated, and that they are really cleared in
info->status.rates after the call to ieee80211_tx_info_clear_status.

Cc: Thomas Huehn <thomas@....t-labs.tu-berlin.de>
Cc: Benjamin Vahl <bvahl@....t-labs.tu-berlin.de>
Reported-by: Ben West <ben@...asabi.net>
Signed-off-by: Felix Fietkau <nbd@...nwrt.org>
Acked-by: Thomas Huehn <thomas@....t-labs.tu-berlin.de>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/ath/ath5k/base.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -1663,15 +1663,15 @@ ath5k_tx_frame_completed(struct ath5k_hw
 	ah->stats.tx_bytes_count += skb->len;
 	info = IEEE80211_SKB_CB(skb);

+	size = min_t(int, sizeof(info->status.rates), sizeof(bf->rates));
+	memcpy(info->status.rates, bf->rates, size);
+
 	tries[0] = info->status.rates[0].count;
 	tries[1] = info->status.rates[1].count;
 	tries[2] = info->status.rates[2].count;

 	ieee80211_tx_info_clear_status(info);

-	size = min_t(int, sizeof(info->status.rates), sizeof(bf->rates));
-	memcpy(info->status.rates, bf->rates, size);
-
 	for (i = 0; i < ts->ts_final_idx; i++) {
 		struct ieee80211_tx_rate *r =
 			&info->status.rates[i];

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