rc80211_minstrel: fix contention window calculation

The contention window is supposed to be a power of two minus one, i.e. 15, 31, 63, 127... minstrel_rate_init() forgets to subtract 1, so the sequence becomes 15, 32, 66, 134... Bug reported by Dan Halperin <dhalperi@cs.washington.edu> Signed-off-by: Pavel Roskin <proski@gnu.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>

rc80211_minstrel: fix contention window calculation
The contention window is supposed to be a power of two minus one, i.e. 15, 31, 63, 127... minstrel_rate_init() forgets to subtract 1, so the sequence becomes 15, 32, 66, 134... Bug reported by Dan Halperin <dhalperi@cs.washington.edu> Signed-off-by: Pavel Roskin <proski@gnu.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Pavel Roskin · John W. Linville
1 parent de32cce132
Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff
net/mac80211/rc80211_minstrel.c
@@ -418,7 +418,7 @@
  
 			/* contention window */
 			tx_time_single += t_slot + min(cw, mp->cw_max);
-			cw = (cw + 1) << 1;
+			cw = (cw << 1) | 1;
  
 			tx_time += tx_time_single;
 			tx_time_cts += tx_time_single + mi->sp_ack_dur;
...	...	@@ -418,7 +418,7 @@
418	418
419	419	/* contention window */
420	420	tx_time_single += t_slot + min(cw, mp->cw_max);
421		- cw = (cw + 1) << 1;
	421	+ cw = (cw << 1) \| 1;
422	422
423	423	tx_time += tx_time_single;
424	424	tx_time_cts += tx_time_single + mi->sp_ack_dur;