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Commit 0ef3ef0f authored by Szymon Janc's avatar Szymon Janc Committed by Johan Hedberg
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Bluetooth: Set P-bit for SREJ frame only if there are I-frames to ack 



SREJ frame with P-bit set acknowledges I-frames numbered up to
(ReqSeq - 1). With this patch P-bit in SREJ is set only when there are
some I-frames to ack.

This fixes ambiguous situation when lost of I-frame with TxSeq=0 would
result in sending SREJ acking all previous I-frames.
Consider following scenario:
TxWindow=3

HostA: sent I-frame TxSeq=0
HostA: sent I-frame TxSeq=1
HostA: sent I-frame TxSeq=2
HostB: missed I-frame TxSeq=0
HostB: received I-frame TxSeq=1
HostB: sent SREJ ReqSeq=0 Pbit=1
HostA: received SREJ ReqSeq=0 Pbit=1   <- All I-frames acked or not?
...

Signed-off-by: default avatarSzymon Janc <szymon.janc@tieto.com>
Acked-by: default avatarMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: default avatarJohan Hedberg <johan.hedberg@intel.com>
parent 75b93b59

net/bluetooth/l2cap_core.c

+3 −3
Original line number Diff line number Diff line
@@ -3927,6 +3927,8 @@ static inline int l2cap_data_channel_iframe(struct l2cap_chan *chan, u32 rx_cont 
		__skb_queue_head_init(&chan->srej_q);

		l2cap_add_to_srej_queue(chan, skb, tx_seq, sar);



		/* Set P-bit only if there are some I-frames to ack. */

		if (__clear_ack_timer(chan))

			set_bit(CONN_SEND_PBIT, &chan->conn_state);



		err = l2cap_send_srejframe(chan, tx_seq);
@@ -3934,8 +3936,6 @@ static inline int l2cap_data_channel_iframe(struct l2cap_chan *chan, u32 rx_cont 
			l2cap_send_disconn_req(chan->conn, chan, -err);

			return err;

		}



		__clear_ack_timer(chan);

	}

	return 0;