From: Loic Poulain <loic.poulain@xxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit 4807b51895dce8aa650ebebc51fa4a795ed6b8b8 upstream. In this expression: seq = (seq - 1) % 8 seq (u8) is implicitly converted to an int in the arithmetic operation. So if seq value is 0, operation is ((0 - 1) % 8) => (-1 % 8) => -1. The new seq value is 0xff which is an invalid ACK value, we expect 0x07. It leads to frequent dropped ACK and retransmission. Fix this by using '&' binary operator instead of '%'. Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxx> Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/bluetooth/hci_h5.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c index db0be2fb05fe..db35c542eb20 100644 --- a/drivers/bluetooth/hci_h5.c +++ b/drivers/bluetooth/hci_h5.c @@ -237,7 +237,7 @@ static void h5_pkt_cull(struct h5 *h5) break; to_remove--; - seq = (seq - 1) % 8; + seq = (seq - 1) & 0x07; } if (seq != h5->rx_ack) -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html