From 5a364bd399d23fe6244de8f84c46f249b763c723 Mon Sep 17 00:00:00 2001 From: Mat Martineau Date: Wed, 25 Apr 2012 16:36:12 -0700 Subject: [PATCH] Bluetooth: Improve ERTM sequence number offset calculation Instead of using modular division, the offset can be calculated using only addition and subtraction. The previous calculation did not work as intended and was more difficult to understand, involving unsigned integer underflow and a check for a negative value where one was not possible. Signed-off-by: Mat Martineau Acked-by: Marcel Holtmann Signed-off-by: Gustavo Padovan --- include/net/bluetooth/l2cap.h | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h index 86bb83b..084dec0 100644 --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -724,13 +724,10 @@ static inline bool l2cap_clear_timer(struct l2cap_chan *chan, static inline int __seq_offset(struct l2cap_chan *chan, __u16 seq1, __u16 seq2) { - int offset; - - offset = (seq1 - seq2) % (chan->tx_win_max + 1); - if (offset < 0) - offset += (chan->tx_win_max + 1); - - return offset; + if (seq1 >= seq2) + return seq1 - seq2; + else + return chan->tx_win_max + 1 - seq2 + seq1; } static inline __u16 __next_seq(struct l2cap_chan *chan, __u16 seq) -- 2.7.4