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Commit 84084a31 authored by Mat Martineau's avatar Mat Martineau Committed by Gustavo F. Padovan
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Bluetooth: Perform L2CAP SDU reassembly without copying data 



Use sk_buff fragment capabilities to link together incoming skbs
instead of allocating a new skb for reassembly and copying.

The new reassembly code works equally well for ERTM and streaming
mode, so there is now one reassembly function instead of two.

Signed-off-by: default avatarMat Martineau <mathewm@codeaurora.org>
Signed-off-by: default avatarGustavo F. Padovan <padovan@profusion.mobi>
parent 5b668eb3

include/net/bluetooth/l2cap.h

+1 −2
Original line number Diff line number Diff line
@@ -354,8 +354,8 @@ struct l2cap_chan { 
	__u8		retry_count;

	__u8		num_acked;

	__u16		sdu_len;

	__u16		partial_sdu_len;

	struct sk_buff	*sdu;

	struct sk_buff	*sdu_last_frag;



	__u8		remote_tx_win;

	__u8		remote_max_tx;
@@ -448,7 +448,6 @@ enum { 
#define L2CAP_CONF_MAX_CONF_RSP 2



enum {

	CONN_SAR_SDU,

	CONN_SREJ_SENT,

	CONN_WAIT_F,

	CONN_SREJ_ACT,

net/bluetooth/l2cap_core.c

+80 −163
Original line number Diff line number Diff line
@@ -3128,102 +3128,104 @@ static int l2cap_add_to_srej_queue(struct l2cap_chan *chan, struct sk_buff *skb, 
	return 0;

}



static int l2cap_ertm_reassembly_sdu(struct l2cap_chan *chan, struct sk_buff *skb, u16 control)

static void append_skb_frag(struct sk_buff *skb,

			struct sk_buff *new_frag, struct sk_buff **last_frag)

{

	struct sk_buff *_skb;

	int err;

	/* skb->len reflects data in skb as well as all fragments

	 * skb->data_len reflects only data in fragments

	 */

	if (!skb_has_frag_list(skb))

		skb_shinfo(skb)->frag_list = new_frag;



	new_frag->next = NULL;



	(*last_frag)->next = new_frag;

	*last_frag = new_frag;



	skb->len += new_frag->len;

	skb->data_len += new_frag->len;

	skb->truesize += new_frag->truesize;

}



static int l2cap_reassemble_sdu(struct l2cap_chan *chan, struct sk_buff *skb, u16 control)

{

	int err = -EINVAL;



	switch (control & L2CAP_CTRL_SAR) {

	case L2CAP_SDU_UNSEGMENTED:

		if (test_bit(CONN_SAR_SDU, &chan->conn_state))

			goto drop;

		if (chan->sdu)

			break;



		return chan->ops->recv(chan->data, skb);

		err = chan->ops->recv(chan->data, skb);

		break;



	case L2CAP_SDU_START:

		if (test_bit(CONN_SAR_SDU, &chan->conn_state))

			goto drop;

		if (chan->sdu)

			break;



		chan->sdu_len = get_unaligned_le16(skb->data);

		skb_pull(skb, 2);



		if (chan->sdu_len > chan->imtu)

			goto disconnect;



		chan->sdu = bt_skb_alloc(chan->sdu_len, GFP_ATOMIC);

		if (!chan->sdu)

			return -ENOMEM;

		if (chan->sdu_len > chan->imtu) {

			err = -EMSGSIZE;

			break;

		}



		/* pull sdu_len bytes only after alloc, because of Local Busy

		 * condition we have to be sure that this will be executed

		 * only once, i.e., when alloc does not fail */

		skb_pull(skb, 2);

		if (skb->len >= chan->sdu_len)

			break;



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);

		chan->sdu = skb;

		chan->sdu_last_frag = skb;



		set_bit(CONN_SAR_SDU, &chan->conn_state);

		chan->partial_sdu_len = skb->len;

		skb = NULL;

		err = 0;

		break;



	case L2CAP_SDU_CONTINUE:

		if (!test_bit(CONN_SAR_SDU, &chan->conn_state))

			goto disconnect;



		if (!chan->sdu)

			goto disconnect;

			break;



		chan->partial_sdu_len += skb->len;

		if (chan->partial_sdu_len > chan->sdu_len)

			goto drop;

		append_skb_frag(chan->sdu, skb,

				&chan->sdu_last_frag);

		skb = NULL;



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);

		if (chan->sdu->len >= chan->sdu_len)

			break;



		err = 0;

		break;



	case L2CAP_SDU_END:

		if (!test_bit(CONN_SAR_SDU, &chan->conn_state))

			goto disconnect;



		if (!chan->sdu)

			goto disconnect;



		chan->partial_sdu_len += skb->len;



		if (chan->partial_sdu_len > chan->imtu)

			goto drop;

			break;



		if (chan->partial_sdu_len != chan->sdu_len)

			goto drop;

		append_skb_frag(chan->sdu, skb,

				&chan->sdu_last_frag);

		skb = NULL;



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);

		if (chan->sdu->len != chan->sdu_len)

			break;



		_skb = skb_clone(chan->sdu, GFP_ATOMIC);

		if (!_skb) {

			return -ENOMEM;

		}

		err = chan->ops->recv(chan->data, chan->sdu);



		err = chan->ops->recv(chan->data, _skb);

		if (err < 0) {

			kfree_skb(_skb);

			return err;

		if (!err) {

			/* Reassembly complete */

			chan->sdu = NULL;

			chan->sdu_last_frag = NULL;

			chan->sdu_len = 0;

		}



		clear_bit(CONN_SAR_SDU, &chan->conn_state);



		kfree_skb(chan->sdu);

		break;

	}



	if (err) {

		kfree_skb(skb);

	return 0;



drop:

		kfree_skb(chan->sdu);

		chan->sdu = NULL;

		chan->sdu_last_frag = NULL;

		chan->sdu_len = 0;

	}



disconnect:

	l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);

	kfree_skb(skb);

	return 0;

	return err;

}



static void l2cap_ertm_enter_local_busy(struct l2cap_chan *chan)
@@ -3277,99 +3279,6 @@ void l2cap_chan_busy(struct l2cap_chan *chan, int busy) 
	}

}



static int l2cap_streaming_reassembly_sdu(struct l2cap_chan *chan, struct sk_buff *skb, u16 control)

{

	struct sk_buff *_skb;

	int err = -EINVAL;



	/*

	 * TODO: We have to notify the userland if some data is lost with the

	 * Streaming Mode.

	 */



	switch (control & L2CAP_CTRL_SAR) {

	case L2CAP_SDU_UNSEGMENTED:

		if (test_bit(CONN_SAR_SDU, &chan->conn_state)) {

			kfree_skb(chan->sdu);

			break;

		}



		err = chan->ops->recv(chan->data, skb);

		if (!err)

			return 0;



		break;



	case L2CAP_SDU_START:

		if (test_bit(CONN_SAR_SDU, &chan->conn_state)) {

			kfree_skb(chan->sdu);

			break;

		}



		chan->sdu_len = get_unaligned_le16(skb->data);

		skb_pull(skb, 2);



		if (chan->sdu_len > chan->imtu) {

			err = -EMSGSIZE;

			break;

		}



		chan->sdu = bt_skb_alloc(chan->sdu_len, GFP_ATOMIC);

		if (!chan->sdu) {

			err = -ENOMEM;

			break;

		}



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);



		set_bit(CONN_SAR_SDU, &chan->conn_state);

		chan->partial_sdu_len = skb->len;

		err = 0;

		break;



	case L2CAP_SDU_CONTINUE:

		if (!test_bit(CONN_SAR_SDU, &chan->conn_state))

			break;



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);



		chan->partial_sdu_len += skb->len;

		if (chan->partial_sdu_len > chan->sdu_len)

			kfree_skb(chan->sdu);

		else

			err = 0;



		break;



	case L2CAP_SDU_END:

		if (!test_bit(CONN_SAR_SDU, &chan->conn_state))

			break;



		memcpy(skb_put(chan->sdu, skb->len), skb->data, skb->len);



		clear_bit(CONN_SAR_SDU, &chan->conn_state);

		chan->partial_sdu_len += skb->len;



		if (chan->partial_sdu_len > chan->imtu)

			goto drop;



		if (chan->partial_sdu_len == chan->sdu_len) {

			_skb = skb_clone(chan->sdu, GFP_ATOMIC);

			err = chan->ops->recv(chan->data, _skb);

			if (err < 0)

				kfree_skb(_skb);

		}

		err = 0;



drop:

		kfree_skb(chan->sdu);

		break;

	}



	kfree_skb(skb);

	return err;

}



static void l2cap_check_srej_gap(struct l2cap_chan *chan, u8 tx_seq)

{

	struct sk_buff *skb;
@@ -3384,7 +3293,7 @@ static void l2cap_check_srej_gap(struct l2cap_chan *chan, u8 tx_seq) 


		skb = skb_dequeue(&chan->srej_q);

		control = bt_cb(skb)->sar << L2CAP_CTRL_SAR_SHIFT;

		err = l2cap_ertm_reassembly_sdu(chan, skb, control);

		err = l2cap_reassemble_sdu(chan, skb, control);



		if (err < 0) {

			l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
@@ -3544,7 +3453,7 @@ static inline int l2cap_data_channel_iframe(struct l2cap_chan *chan, u16 rx_cont 
		return 0;

	}



	err = l2cap_ertm_reassembly_sdu(chan, skb, rx_control);

	err = l2cap_reassemble_sdu(chan, skb, rx_control);

	chan->buffer_seq = (chan->buffer_seq + 1) % 64;

	if (err < 0) {

		l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
@@ -3860,12 +3769,20 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk 


		tx_seq = __get_txseq(control);



		if (chan->expected_tx_seq == tx_seq)

			chan->expected_tx_seq = (chan->expected_tx_seq + 1) % 64;

		else

		if (chan->expected_tx_seq != tx_seq) {

			/* Frame(s) missing - must discard partial SDU */

			kfree_skb(chan->sdu);

			chan->sdu = NULL;

			chan->sdu_last_frag = NULL;

			chan->sdu_len = 0;



			/* TODO: Notify userland of missing data */

		}



		chan->expected_tx_seq = (tx_seq + 1) % 64;



		l2cap_streaming_reassembly_sdu(chan, skb, control);

		if (l2cap_reassemble_sdu(chan, skb, control) == -EMSGSIZE)

			l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);



		goto done;