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authorDaniel Halperin <dhalperi@cs.washington.edu>2011-05-11 06:00:45 +0400
committerJohn W. Linville <linville@tuxdriver.com>2011-05-12 22:10:48 +0400
commit8fddddff0ad4ccc2787464207eba9ed3063e69cd (patch)
tree6f219c46e9fdae5df766deb784c3cfc00e3e4106 /net/mac80211/rc80211_minstrel.c
parent56d1893d94bc06d0b1aa3a53f924ed02f9e207bf (diff)
downloadlinux-8fddddff0ad4ccc2787464207eba9ed3063e69cd.tar.xz
mac80211: fix contention time computation in minstrel, minstrel_ht
When transmitting a frame, the transmitter waits a random number of slots between 0 and cw. Thus, the contention time is (cw / 2) * t_slot which we can represent instead as (cw * t_slot) >> 1. Also fix a few other accounting bugs around contention time, and add comments. Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/mac80211/rc80211_minstrel.c')
-rw-r--r--net/mac80211/rc80211_minstrel.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
index 778c604d7939..8adac67395f7 100644
--- a/net/mac80211/rc80211_minstrel.c
+++ b/net/mac80211/rc80211_minstrel.c
@@ -417,8 +417,8 @@ minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
tx_time_single = mr->ack_time + mr->perfect_tx_time;
/* contention window */
- tx_time_single += t_slot + min(cw, mp->cw_max);
- cw = (cw << 1) | 1;
+ tx_time_single += (t_slot * cw) >> 1;
+ cw = min((cw << 1) | 1, mp->cw_max);
tx_time += tx_time_single;
tx_time_cts += tx_time_single + mi->sp_ack_dur;