Re: [PATCHv4 10/18] Bluetooth: Add logical link confirm

[Mat Martineau <mathewm@codeaurora.org>]

Marcel -

On Tue, 23 Oct 2012, Marcel Holtmann wrote:

> Hi Mat,
>
>> The logical link confirm callback is executed when the AMP controller
>> completes its logical link setup.  During a channel move, a newly
>> formed logical link allows a move responder to send a move channel
>> response.  A move initiator will send a move channel confirm.  A
>> failed logical link will end the channel move and send an appropriate
>> response or confirm command indicating a failure.
>>
>> If the channel is being created on an AMP controller, L2CAP
>> configuration is completed after the logical link is set up.
>>
>> Signed-off-by: Mat Martineau <mathewm@codeaurora.org>
>> ---
>>  net/bluetooth/l2cap_core.c | 124 ++++++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 116 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
>> index 69d43c9..0edc955 100644
>> --- a/net/bluetooth/l2cap_core.c
>> +++ b/net/bluetooth/l2cap_core.c
>> @@ -3799,6 +3799,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
>>  		goto unlock;
>>  	}
>>
>> +	chan->ident = cmd->ident;
>>  	l2cap_send_cmd(conn, cmd->ident, L2CAP_CONF_RSP, len, rsp);
>>  	chan->num_conf_rsp++;
>>
>> @@ -4198,17 +4199,17 @@ static int l2cap_create_channel_req(struct l2cap_conn *conn,
>>  	return 0;
>>  }
>>
>> -static void l2cap_send_move_chan_rsp(struct l2cap_conn *conn, u8 ident,
>> -				     u16 icid, u16 result)
>> +static void l2cap_send_move_chan_rsp(struct l2cap_chan *chan, u16 result)
>>  {
>>  	struct l2cap_move_chan_rsp rsp;
>>
>> -	BT_DBG("icid 0x%4.4x, result 0x%4.4x", icid, result);
>> +	BT_DBG("chan %p, result 0x%4.4x", chan, result);
>>
>> -	rsp.icid = cpu_to_le16(icid);
>> +	rsp.icid = cpu_to_le16(chan->dcid);
>>  	rsp.result = cpu_to_le16(result);
>>
>> -	l2cap_send_cmd(conn, ident, L2CAP_MOVE_CHAN_RSP, sizeof(rsp), &rsp);
>> +	l2cap_send_cmd(chan->conn, chan->ident, L2CAP_MOVE_CHAN_RSP,
>> +		       sizeof(rsp), &rsp);
>>  }
>>
>>  static void l2cap_send_move_chan_cfm(struct l2cap_chan *chan, u16 result)
>> @@ -4260,11 +4261,114 @@ static void __release_logical_link(struct l2cap_chan *chan)
>>  	/* Placeholder - release the logical link */
>>  }
>>
>> +static void l2cap_logical_fail(struct l2cap_chan *chan)
>> +{
>> +	/* Logical link setup failed */
>> +	if (chan->state != BT_CONNECTED) {
>> +		/* Create channel failure, disconnect */
>> +		l2cap_send_disconn_req(chan->conn, chan, ECONNRESET);
>
> lets do this:
>
> 	if (chan->state != BT_CONNECTED) {
> 		...
> 		return;
> 	}
>

Ok.

>> +	} else if (chan->move_role == L2CAP_MOVE_ROLE_RESPONDER) {
>> +		l2cap_move_revert(chan);
>> +		chan->move_role = L2CAP_MOVE_ROLE_NONE;
>> +		chan->move_state = L2CAP_MOVE_STABLE;
>> +		l2cap_send_move_chan_rsp(chan, L2CAP_MR_NOT_SUPP);
>> +	} else if (chan->move_role == L2CAP_MOVE_ROLE_INITIATOR) {
>> +		if (chan->move_state == L2CAP_MOVE_WAIT_LOGICAL_COMP ||
>> +		    chan->move_state == L2CAP_MOVE_WAIT_LOGICAL_CFM) {
>> +			/* Remote has only sent pending or
>> +			 * success responses, clean up
>> +			 */
>> +			l2cap_move_revert(chan);
>> +			chan->move_role = L2CAP_MOVE_ROLE_NONE;
>> +			chan->move_state = L2CAP_MOVE_STABLE;
>> +		}
>> +
>> +		/* Other amp move states imply that the move
>> +		 * has already aborted
>> +		 */
>> +		l2cap_send_move_chan_cfm(chan, L2CAP_MC_UNCONFIRMED);
>> +	}
>
> And turn this into a switch statement.
>
>> +
>> +	__release_logical_link(chan);
>
> And leave this to the caller.
>

Ok.

>> +}
>> +
>> +static void l2cap_logical_finish_create(struct l2cap_chan *chan,
>> +					struct hci_chan *hchan)
>> +{
>> +	struct l2cap_conf_rsp rsp;
>> +	u8 code;
>> +
>> +	chan->hs_hcon = hchan->conn;
>> +	chan->hs_hcon->l2cap_data = chan->conn;
>> +
>> +	code = l2cap_build_conf_rsp(chan, &rsp,
>> +				    L2CAP_CONF_SUCCESS, 0);
>> +	l2cap_send_cmd(chan->conn, chan->ident, L2CAP_CONF_RSP, code,
>> +		       &rsp);
>> +	set_bit(CONF_OUTPUT_DONE, &chan->conf_state);
>> +
>> +	if (test_bit(CONF_INPUT_DONE, &chan->conf_state)) {
>> +		int err = 0;
>> +
>> +		set_default_fcs(chan);
>> +
>> +		err = l2cap_ertm_init(chan);
>> +		if (err < 0)
>> +			l2cap_send_disconn_req(chan->conn, chan, -err);
>> +		else
>> +			l2cap_chan_ready(chan);
>> +	}
>> +}
>> +
>> +static void l2cap_logical_finish_move(struct l2cap_chan *chan,
>> +				      struct hci_chan *hchan)
>> +{
>> +	chan->hs_hcon = hchan->conn;
>> +	chan->hs_hcon->l2cap_data = chan->conn;
>> +
>> +	BT_DBG("move_state %d", chan->move_state);
>> +
>> +	switch (chan->move_state) {
>> +	case L2CAP_MOVE_WAIT_LOGICAL_COMP:
>> +		/* Move confirm will be sent after a success
>> +		 * response is received
>> +		 */
>> +		chan->move_state = L2CAP_MOVE_WAIT_RSP_SUCCESS;
>> +		break;
>> +	case L2CAP_MOVE_WAIT_LOGICAL_CFM:
>> +		if (test_bit(CONN_LOCAL_BUSY, &chan->conn_state)) {
>> +			chan->move_state = L2CAP_MOVE_WAIT_LOCAL_BUSY;
>
> My brain just hurts from these nested if-else. A nested two switch does
> not make it any better though. So we can leave it as this. Except the
> statement below is used multiple places and we have a function for it.
>

This version (v4) of the patch reflects some consolidation in these 
statements already, where I put more code inside 
l2cap_send_move_chan_cfm and l2cap_send_move_chan_rsp.  The move_state 
assignments don't fit well in those helper functions.

The next 7 lines of code are not duplicated anywhere else.  The first 
block (L2CAP_MOVE_WAIT_CONFIRM_RSP + send confirm) is used in one 
other place.  The second block (L2CAP_MOVE_WAIT_CONFIRM + send 
response) is also used in just one other place -- but a different one. 
The surrounding logic based on chan->move_role is not shared.

Do you want me to create 2-line helper functions for each case, or 
were you thinking there was more duplicated code around?  Adding new 
functions is a net gain in lines of code and doesn't seem like a big 
win for clarity.


>> +		} else if (chan->move_role == L2CAP_MOVE_ROLE_INITIATOR) {
>> +			chan->move_state = L2CAP_MOVE_WAIT_CONFIRM_RSP;
>> +			l2cap_send_move_chan_cfm(chan, L2CAP_MC_CONFIRMED);
>> +		} else if (chan->move_role == L2CAP_MOVE_ROLE_RESPONDER) {
>> +			chan->move_state = L2CAP_MOVE_WAIT_CONFIRM;
>> +			l2cap_send_move_chan_rsp(chan, L2CAP_MR_SUCCESS);
>> +		}
>> +		break;
>> +	default:
>> +		/* Move was not in expected state, free the channel */
>> +		__release_logical_link(chan);
>> +
>> +		chan->move_state = L2CAP_MOVE_STABLE;
>> +	}
>> +}
>> +
>> +/* Call with chan locked */
>>  static void l2cap_logical_cfm(struct l2cap_chan *chan, struct hci_chan *hchan,
>>  			      u8 status)
>>  {
>> -	/* Placeholder */
>> -	return;
>> +	BT_DBG("chan %p, hchan %p, status %d", chan, hchan, status);
>> +
>> +	if (status) {
>> +		l2cap_logical_fail(chan);
>
> I rather have a return here.
>
> 	if (status) {
> 		l2cap_logical_fail(chan);
> 		__release_logical_link(chan);
> 		return;
> 	}
>

Ok.

>> +	} else if (chan->state != BT_CONNECTED) {
>> +		/* Ignore logical link if channel is on BR/EDR */
>> +		if (chan->local_amp_id)
>> +			l2cap_logical_finish_create(chan, hchan);
>> +	} else {
>> +		l2cap_logical_finish_move(chan, hchan);
>> +	}
>>  }
>>
>>  static inline int l2cap_move_channel_req(struct l2cap_conn *conn,
>> @@ -4272,6 +4376,7 @@ static inline int l2cap_move_channel_req(struct l2cap_conn *conn,
>>  					 u16 cmd_len, void *data)
>>  {
>>  	struct l2cap_move_chan_req *req = data;
>> +	struct l2cap_move_chan_rsp rsp;
>>  	struct l2cap_chan *chan;
>>  	u16 icid = 0;
>>  	u16 result = L2CAP_MR_NOT_ALLOWED;
>> @@ -4348,7 +4453,10 @@ static inline int l2cap_move_channel_req(struct l2cap_conn *conn,
>>  	}
>>
>>  send_move_response:
>> -	l2cap_send_move_chan_rsp(conn, cmd->ident, icid, result);
>> +	rsp.icid = cpu_to_le16(icid);
>> +	rsp.result = cpu_to_le16(result);
>> +	l2cap_send_cmd(conn, cmd->ident, L2CAP_MOVE_CHAN_RSP,
>> +		       sizeof(rsp), &rsp);
>>
>>  	if (chan)
>>  		l2cap_chan_unlock(chan);
>
> While not part of this patch, I still dislike if (something) unlock
> style. Please have that fixed as well.

I'll fix it.  This is the only "if (chan) / unlock" case left.

> Rest looks fine.


Thanks,

--
Mat Martineau

Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation