[RFC v4 00/12] LE auto connection and connection parameters

[RFC v4 00/12] LE auto connection and connection parameters

[Andre Guedes]

Hi all,

This v4 is the same patch set from v3 but rebased on top of current
bluetooth-next tree.

Below follows v3 cover letter:

The main changes from the previous version are:
  * Debugfs interface to add auto connect address instead of new mgmt
    commands.
  * We always stop LE scanning in favor of connection establishment even if
    the controller supports scanning and connection at the same time.
  * Background scanning is now controlled in one single place (hci_update_
    background_scan function).
  * RCU was replaced by hdev->lock to protect hdev->le_conn_params list. After
    all the changes since the original version of this patch set, I realized
    we always operate on hdev->le_conn_params with hdev->lock held so there is
    no point in use RCU to protect this list.

In order to test the LE auto connection mechanism please follow the
instructions below.

To add a new auto connection address we write on le_auto_conn file following
the format <address> <address type> <auto_connect>.

The <address type> values are:
  * 0 for public address
  * 1 for random address

The <auto_connect> values are (for more details see struct hci_conn_params):
  * 0 for disabled
  * 1 for always
  * 2 for link loss

So for instance, if you want the kernel autonomously establishes connections
with device AA:BB:CC:DD:EE:FF (public address) every time the device enters in
connectable mode (starts advertising), you should run the command:
$ echo "AA:BB:CC:DD:EE:FF 0 1" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To get the list of connection parameters configured in kernel, read the
le_auto_conn file:
$ cat /sys/kernel/debug/bluetooth/hci0/le_auto_conn

Finally, to clear the connection parameters list, write an empty string:
$ echo "" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

BR,

Andre


Andre Guedes (12):
  Bluetooth: Save connection interval parameters in hci_conn
  Bluetooth: Group list_head fields from strcut hci_dev together
  Bluetooth: Introduce connection parameters list
  Bluetooth: Use connection parameters if any
  Bluetooth: Stop scanning on LE connection
  Bluetooth: Introduce hdev->pend_le_conn list
  Bluetooth: Introduce LE auto connection infrastructure
  Bluetooth: Re-enable background scan in case of error
  Bluetooth: Temporarily stop background scanning on discovery
  Bluetooth: Auto connection and power on
  Bleutooth: Add support for auto connect options
  Bluetooth: Add le_auto_conn file on debugfs

 include/net/bluetooth/hci_core.h |  43 +++++-
 net/bluetooth/hci_conn.c         |  39 ++++-
 net/bluetooth/hci_core.c         | 318 +++++++++++++++++++++++++++++++++++++++
 net/bluetooth/hci_event.c        |  60 ++++++++
 net/bluetooth/mgmt.c             |  25 ++-
 5 files changed, 473 insertions(+), 12 deletions(-)

-- 
1.8.4.2

[RFC v4 01/12] Bluetooth: Save connection interval parameters in hci_conn

[Andre Guedes]

This patch creates two new fields in struct hci_conn to save the
minimum and maximum connection interval values used to establish
the connection this object represents.

This change is required in order to know what parameters the
connection is currently using.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 include/net/bluetooth/hci_core.h | 2 ++
 net/bluetooth/hci_conn.c         | 6 ++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index f8555ad7..434ab31 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -332,6 +332,8 @@ struct hci_conn {
 	__u8		passkey_entered;
 	__u16		disc_timeout;
 	__u16		setting;
+	__u16		le_conn_min_interval;
+	__u16		le_conn_max_interval;
 	unsigned long	flags;
 
 	__u8		remote_cap;
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index ba5366c..15c689e 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -558,8 +558,8 @@ static int hci_create_le_conn(struct hci_conn *conn)
 	bacpy(&cp.peer_addr, &conn->dst);
 	cp.peer_addr_type = conn->dst_type;
 	cp.own_address_type = conn->src_type;
-	cp.conn_interval_min = cpu_to_le16(hdev->le_conn_min_interval);
-	cp.conn_interval_max = cpu_to_le16(hdev->le_conn_max_interval);
+	cp.conn_interval_min = cpu_to_le16(conn->le_conn_min_interval);
+	cp.conn_interval_max = cpu_to_le16(conn->le_conn_max_interval);
 	cp.supervision_timeout = __constant_cpu_to_le16(0x002a);
 	cp.min_ce_len = __constant_cpu_to_le16(0x0000);
 	cp.max_ce_len = __constant_cpu_to_le16(0x0000);
@@ -624,6 +624,8 @@ static struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 	conn->sec_level = BT_SECURITY_LOW;
 	conn->pending_sec_level = sec_level;
 	conn->auth_type = auth_type;
+	conn->le_conn_min_interval = hdev->le_conn_min_interval;
+	conn->le_conn_max_interval = hdev->le_conn_max_interval;
 
 	err = hci_create_le_conn(conn);
 	if (err)
-- 
1.8.4.2

[RFC v4 02/12] Bluetooth: Group list_head fields from strcut hci_dev together

[Andre Guedes]

This patch groups the list_head fields from struct hci_dev together
and removes empty lines between them.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 include/net/bluetooth/hci_core.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 434ab31..daa6193 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -257,18 +257,15 @@ struct hci_dev {
 	__u32			req_status;
 	__u32			req_result;
 
-	struct list_head	mgmt_pending;
 
 	struct discovery_state	discovery;
 	struct hci_conn_hash	conn_hash;
-	struct list_head	blacklist;
 
+	struct list_head	mgmt_pending;
+	struct list_head	blacklist;
 	struct list_head	uuids;
-
 	struct list_head	link_keys;
-
 	struct list_head	long_term_keys;
-
 	struct list_head	remote_oob_data;
 
 	struct hci_dev_stats	stat;
-- 
1.8.4.2

[RFC v4 03/12] Bluetooth: Introduce connection parameters list

[Andre Guedes]

This patch adds to hdev the connection parameters list (hdev->le_
conn_params). The elements from this list (struct hci_conn_params)
contains the connection parameters (for now, minimum and maximum
connection interval) that should be used during the connection
establishment.

The struct hci_conn_params also defines the 'auto_connect' field
which will be used to implement the auto connection mechanism.

Moreover, this patch adds helper functions to manipulate hdev->le_
conn_params list. Some of these functions are also declared in
hci_core.h since they will be used outside hci_core.c in upcoming
patches.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 include/net/bluetooth/hci_core.h | 25 +++++++++++++
 net/bluetooth/hci_core.c         | 80 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index daa6193..a35b90d 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -267,6 +267,7 @@ struct hci_dev {
 	struct list_head	link_keys;
 	struct list_head	long_term_keys;
 	struct list_head	remote_oob_data;
+	struct list_head	le_conn_params;
 
 	struct hci_dev_stats	stat;
 
@@ -371,6 +372,22 @@ struct hci_chan {
 	__u8		state;
 };
 
+struct hci_conn_params {
+	struct list_head list;
+
+	bdaddr_t addr;
+	u8 addr_type;
+
+	enum {
+		HCI_AUTO_CONN_DISABLED,
+		HCI_AUTO_CONN_ALWAYS,
+		HCI_AUTO_CONN_LINK_LOSS,
+	} auto_connect;
+
+	u16 conn_min_interval;
+	u16 conn_max_interval;
+};
+
 extern struct list_head hci_dev_list;
 extern struct list_head hci_cb_list;
 extern rwlock_t hci_dev_list_lock;
@@ -739,6 +756,14 @@ int hci_blacklist_clear(struct hci_dev *hdev);
 int hci_blacklist_add(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 type);
 int hci_blacklist_del(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 type);
 
+struct hci_conn_params *hci_conn_params_lookup(struct hci_dev *hdev,
+					       bdaddr_t *addr, u8 addr_type);
+void hci_conn_params_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type,
+			 u8 auto_connect, u16 conn_min_interval,
+			 u16 conn_max_interval);
+void hci_conn_params_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
+void hci_conn_params_clear(struct hci_dev *hdev);
+
 int hci_uuids_clear(struct hci_dev *hdev);
 
 int hci_link_keys_clear(struct hci_dev *hdev);
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 03e8355..dd9a25c 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2773,6 +2773,84 @@ int hci_blacklist_del(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 type)
 	return mgmt_device_unblocked(hdev, bdaddr, type);
 }
 
+/* This function requires the caller holds hdev->lock */
+struct hci_conn_params *hci_conn_params_lookup(struct hci_dev *hdev,
+					       bdaddr_t *addr, u8 addr_type)
+{
+	struct hci_conn_params *params;
+
+	list_for_each_entry(params, &hdev->le_conn_params, list) {
+		if (bacmp(&params->addr, addr) == 0 &&
+		    params->addr_type == addr_type) {
+			return params;
+		}
+	}
+
+	return NULL;
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_conn_params_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type,
+			 u8 auto_connect, u16 conn_min_interval,
+			 u16 conn_max_interval)
+{
+	struct hci_conn_params *params;
+
+	params = hci_conn_params_lookup(hdev, addr, addr_type);
+	if (params) {
+		params->auto_connect = auto_connect;
+		params->conn_min_interval = conn_min_interval;
+		params->conn_max_interval = conn_max_interval;
+		return;
+	}
+
+	params = kzalloc(sizeof(*params), GFP_KERNEL);
+	if (!params) {
+		BT_ERR("Out of memory");
+		return;
+	}
+
+	bacpy(&params->addr, addr);
+	params->addr_type = addr_type;
+	params->auto_connect = auto_connect;
+	params->conn_min_interval = conn_min_interval;
+	params->conn_max_interval = conn_max_interval;
+
+	list_add(&params->list, &hdev->le_conn_params);
+
+	BT_DBG("addr %pMR (type %u) auto_connect %u conn_min_interval 0x%.4x "
+	       "conn_max_interval 0x%.4x", addr, addr_type, auto_connect,
+	       conn_min_interval, conn_max_interval);
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_conn_params_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
+{
+	struct hci_conn_params *params;
+
+	params = hci_conn_params_lookup(hdev, addr, addr_type);
+	if (!params)
+		return;
+
+	list_del(&params->list);
+	kfree(params);
+
+	BT_DBG("addr %pMR (type %u)", addr, addr_type);
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_conn_params_clear(struct hci_dev *hdev)
+{
+	struct hci_conn_params *params, *tmp;
+
+	list_for_each_entry_safe(params, tmp, &hdev->le_conn_params, list) {
+		list_del(&params->list);
+		kfree(params);
+	}
+
+	BT_DBG("All LE connection parameters were removed");
+}
+
 static void inquiry_complete(struct hci_dev *hdev, u8 status)
 {
 	if (status) {
@@ -2883,6 +2961,7 @@ struct hci_dev *hci_alloc_dev(void)
 	INIT_LIST_HEAD(&hdev->link_keys);
 	INIT_LIST_HEAD(&hdev->long_term_keys);
 	INIT_LIST_HEAD(&hdev->remote_oob_data);
+	INIT_LIST_HEAD(&hdev->le_conn_params);
 	INIT_LIST_HEAD(&hdev->conn_hash.list);
 
 	INIT_WORK(&hdev->rx_work, hci_rx_work);
@@ -3068,6 +3147,7 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	hci_link_keys_clear(hdev);
 	hci_smp_ltks_clear(hdev);
 	hci_remote_oob_data_clear(hdev);
+	hci_conn_params_clear(hdev);
 	hci_dev_unlock(hdev);
 
 	hci_dev_put(hdev);
-- 
1.8.4.2

[RFC v4 04/12] Bluetooth: Use connection parameters if any

[Andre Guedes]

This patch changes hci_connect_le() so it uses the connection
parameters specified for the certain device. If no parameters
were configured, we use the default values.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_conn.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 15c689e..b5c3ebff 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -578,6 +578,7 @@ static int hci_create_le_conn(struct hci_conn *conn)
 static struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 				    u8 dst_type, u8 sec_level, u8 auth_type)
 {
+	struct hci_conn_params *params;
 	struct hci_conn *conn;
 	int err;
 
@@ -624,8 +625,15 @@ static struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
 	conn->sec_level = BT_SECURITY_LOW;
 	conn->pending_sec_level = sec_level;
 	conn->auth_type = auth_type;
-	conn->le_conn_min_interval = hdev->le_conn_min_interval;
-	conn->le_conn_max_interval = hdev->le_conn_max_interval;
+
+	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
+	if (params) {
+		conn->le_conn_min_interval = params->conn_min_interval;
+		conn->le_conn_max_interval = params->conn_max_interval;
+	} else {
+		conn->le_conn_min_interval = hdev->le_conn_min_interval;
+		conn->le_conn_max_interval = hdev->le_conn_max_interval;
+	}
 
 	err = hci_create_le_conn(conn);
 	if (err)
-- 
1.8.4.2

[RFC v4 05/12] Bluetooth: Stop scanning on LE connection

[Andre Guedes]

Some LE controllers don't support scanning and creating a connection
at the same time. So we should always stop scanning in order to
establish the connection.

Since we may prematurely stop the discovery procedure in favor of
the connection establishment, we should also cancel hdev->le_scan_
disable delayed work and set the discovery state to DISCOVERY_STOPPED.

This change does a small improvement since it is not mandatory the
user stops scanning before connecting anymore. Moreover, this change
is required by upcoming LE auto connection mechanism in order to work
properly with controllers that don't support background scanning and
connection establishment at the same time.

In future, we might want to do a small optimization by checking if
controller is able to scan and connect at the same time. For now,
we want the simplest approach so we always stop scanning (even if
the controller is able to carry out both operations).

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_conn.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index b5c3ebff..750a39d 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -518,8 +518,17 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
 {
 	struct hci_conn *conn;
 
-	if (status == 0)
+	if (status == 0) {
+		/* If the discovery procedure was running, we prematurely
+		 * stopped it. So we have to change the discovery state.
+		 */
+		if (hdev->discovery.state == DISCOVERY_FINDING) {
+			cancel_delayed_work(&hdev->le_scan_disable);
+			hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
+		}
+
 		return;
+	}
 
 	BT_ERR("HCI request failed to create LE connection: status 0x%2.2x",
 	       status);
@@ -552,6 +561,18 @@ static int hci_create_le_conn(struct hci_conn *conn)
 
 	hci_req_init(&req, hdev);
 
+	/* If controller is scanning, we stop it since some controllers are
+	 * not able to scan and connect at the same time.
+	 */
+	if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
+		struct hci_cp_le_set_scan_enable enable_cp;
+
+		memset(&enable_cp, 0, sizeof(enable_cp));
+		enable_cp.enable = LE_SCAN_DISABLE;
+		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
+			    &enable_cp);
+	}
+
 	memset(&cp, 0, sizeof(cp));
 	cp.scan_interval = cpu_to_le16(hdev->le_scan_interval);
 	cp.scan_window = cpu_to_le16(hdev->le_scan_window);
-- 
1.8.4.2

Re: [RFC v4 05/12] Bluetooth: Stop scanning on LE connection

[Johan Hedberg]

Hi Andre,

On Fri, Dec 06, 2013, Andre Guedes wrote:
> Some LE controllers don't support scanning and creating a connection
> at the same time. So we should always stop scanning in order to
> establish the connection.
> 
> Since we may prematurely stop the discovery procedure in favor of
> the connection establishment, we should also cancel hdev->le_scan_
> disable delayed work and set the discovery state to DISCOVERY_STOPPED.
> 
> This change does a small improvement since it is not mandatory the
> user stops scanning before connecting anymore. Moreover, this change
> is required by upcoming LE auto connection mechanism in order to work
> properly with controllers that don't support background scanning and
> connection establishment at the same time.
> 
> In future, we might want to do a small optimization by checking if
> controller is able to scan and connect at the same time. For now,
> we want the simplest approach so we always stop scanning (even if
> the controller is able to carry out both operations).
> 
> Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
> ---
>  net/bluetooth/hci_conn.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index b5c3ebff..750a39d 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -518,8 +518,17 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
>  {
>  	struct hci_conn *conn;
>  
> -	if (status == 0)
> +	if (status == 0) {
> +		/* If the discovery procedure was running, we prematurely
> +		 * stopped it. So we have to change the discovery state.
> +		 */
> +		if (hdev->discovery.state == DISCOVERY_FINDING) {
> +			cancel_delayed_work(&hdev->le_scan_disable);
> +			hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
> +		}
> +
>  		return;
> +	}
>  
>  	BT_ERR("HCI request failed to create LE connection: status 0x%2.2x",
>  	       status);
> @@ -552,6 +561,18 @@ static int hci_create_le_conn(struct hci_conn *conn)
>  
>  	hci_req_init(&req, hdev);
>  
> +	/* If controller is scanning, we stop it since some controllers are
> +	 * not able to scan and connect at the same time.
> +	 */
> +	if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
> +		struct hci_cp_le_set_scan_enable enable_cp;
> +
> +		memset(&enable_cp, 0, sizeof(enable_cp));
> +		enable_cp.enable = LE_SCAN_DISABLE;
> +		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
> +			    &enable_cp);
> +	}
> +
>  	memset(&cp, 0, sizeof(cp));
>  	cp.scan_interval = cpu_to_le16(hdev->le_scan_interval);
>  	cp.scan_window = cpu_to_le16(hdev->le_scan_window);

The way this all hangs together with a discovery process started through
mgmt_start_discovery feels a bit flimsy to me. Particularly, have you
ensured that everything is fine if you've got inquiry ongoing when you
do hci_discovery_set_state(hdev, DISCOVERY_STOPPED). Also, are there any
risks of race conditions here, e.g. is it fine to let the
cancel_delayed_work() call be in create_le_conn_complete() instead of
doing it in hci_create_le_conn()?

What also makes this hard to track is that the condition you're testing
for first is the HCI_LE_SCAN bit, but then later you look at
discovery.state == DISCOVERY_FINDING. For the casual reader there's no
direct indication of how these two are releated for the various types of
discovery that are possible (LE-only, BR/EDR-only and interleaved).

I don't mean to say that this is a nack for the patch, but I'd like to
know that you've considered and tested this kind of cases. I had to
spend quite some time looking through the existing code and this patch
and still couldn't arrive at absolute confidence of its correctness,
meaning there should hopefully be some room for simplification.

Johan

Re: [RFC v4 05/12] Bluetooth: Stop scanning on LE connection

[Andre Guedes]

Hi Johan,

Sorry the delay to reply, I was out of the office last week.

On Tue, 2013-12-10 at 15:21 +0200, Johan Hedberg wrote:
> Hi Andre,
> 
> On Fri, Dec 06, 2013, Andre Guedes wrote:
> > Some LE controllers don't support scanning and creating a connection
> > at the same time. So we should always stop scanning in order to
> > establish the connection.
> > 
> > Since we may prematurely stop the discovery procedure in favor of
> > the connection establishment, we should also cancel hdev->le_scan_
> > disable delayed work and set the discovery state to DISCOVERY_STOPPED.
> > 
> > This change does a small improvement since it is not mandatory the
> > user stops scanning before connecting anymore. Moreover, this change
> > is required by upcoming LE auto connection mechanism in order to work
> > properly with controllers that don't support background scanning and
> > connection establishment at the same time.
> > 
> > In future, we might want to do a small optimization by checking if
> > controller is able to scan and connect at the same time. For now,
> > we want the simplest approach so we always stop scanning (even if
> > the controller is able to carry out both operations).
> > 
> > Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
> > ---
> >  net/bluetooth/hci_conn.c | 23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> > 
> > diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> > index b5c3ebff..750a39d 100644
> > --- a/net/bluetooth/hci_conn.c
> > +++ b/net/bluetooth/hci_conn.c
> > @@ -518,8 +518,17 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
> >  {
> >  	struct hci_conn *conn;
> >  
> > -	if (status == 0)
> > +	if (status == 0) {
> > +		/* If the discovery procedure was running, we prematurely
> > +		 * stopped it. So we have to change the discovery state.
> > +		 */
> > +		if (hdev->discovery.state == DISCOVERY_FINDING) {
> > +			cancel_delayed_work(&hdev->le_scan_disable);
> > +			hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
> > +		}
> > +
> >  		return;
> > +	}
> >  
> >  	BT_ERR("HCI request failed to create LE connection: status 0x%2.2x",
> >  	       status);
> > @@ -552,6 +561,18 @@ static int hci_create_le_conn(struct hci_conn *conn)
> >  
> >  	hci_req_init(&req, hdev);
> >  
> > +	/* If controller is scanning, we stop it since some controllers are
> > +	 * not able to scan and connect at the same time.
> > +	 */
> > +	if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
> > +		struct hci_cp_le_set_scan_enable enable_cp;
> > +
> > +		memset(&enable_cp, 0, sizeof(enable_cp));
> > +		enable_cp.enable = LE_SCAN_DISABLE;
> > +		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
> > +			    &enable_cp);
> > +	}
> > +
> >  	memset(&cp, 0, sizeof(cp));
> >  	cp.scan_interval = cpu_to_le16(hdev->le_scan_interval);
> >  	cp.scan_window = cpu_to_le16(hdev->le_scan_window);
> 
> The way this all hangs together with a discovery process started through
> mgmt_start_discovery feels a bit flimsy to me. Particularly, have you
> ensured that everything is fine if you've got inquiry ongoing when you
> do hci_discovery_set_state(hdev, DISCOVERY_STOPPED). Also, are there any
> risks of race conditions here, e.g. is it fine to let the
> cancel_delayed_work() call be in create_le_conn_complete() instead of
> doing it in hci_create_le_conn()?

Yes, I did lots of testing, including the inquiry test you mentioned,
and I didn't find any issues.

I failed to see any race conditons since cancel_delayed_work() does not
block. So it is fine to call cancel_delayed_work() in
create_le_conn_complete() as well as in hci_create_le_conn().

> What also makes this hard to track is that the condition you're testing
> for first is the HCI_LE_SCAN bit, but then later you look at
> discovery.state == DISCOVERY_FINDING. For the casual reader there's no
> direct indication of how these two are releated for the various types of
> discovery that are possible (LE-only, BR/EDR-only and interleaved).

Yes, I see your point. However, we can't check HCI_LE_SCAN in
create_le_conn_complete() because the flag was already cleared in
hci_cc_le_set_scan_enable().

> I don't mean to say that this is a nack for the patch, but I'd like to
> know that you've considered and tested this kind of cases. I had to
> spend quite some time looking through the existing code and this patch
> and still couldn't arrive at absolute confidence of its correctness,
> meaning there should hopefully be some room for simplification.

So I think we can do some simplification by moving this discovery
handling from create_le_conn_complete() to hci_create_le_conn(), at
least I think this code will become a bit easier to follow. What do you
think?

Regards,

Andre

Re: [RFC v4 05/12] Bluetooth: Stop scanning on LE connection

[Johan Hedberg]

Hi Andre,

On Tue, Dec 17, 2013, Andre Guedes wrote:
> > > @@ -518,8 +518,17 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
> > >  {
> > >  	struct hci_conn *conn;
> > >  
> > > -	if (status == 0)
> > > +	if (status == 0) {
> > > +		/* If the discovery procedure was running, we prematurely
> > > +		 * stopped it. So we have to change the discovery state.
> > > +		 */
> > > +		if (hdev->discovery.state == DISCOVERY_FINDING) {
> > > +			cancel_delayed_work(&hdev->le_scan_disable);
> > > +			hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
> > > +		}
> > > +
> > >  		return;
> > > +	}
> > >  
> > >  	BT_ERR("HCI request failed to create LE connection: status 0x%2.2x",
> > >  	       status);
> > > @@ -552,6 +561,18 @@ static int hci_create_le_conn(struct hci_conn *conn)
> > >  
> > >  	hci_req_init(&req, hdev);
> > >  
> > > +	/* If controller is scanning, we stop it since some controllers are
> > > +	 * not able to scan and connect at the same time.
> > > +	 */
> > > +	if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
> > > +		struct hci_cp_le_set_scan_enable enable_cp;
> > > +
> > > +		memset(&enable_cp, 0, sizeof(enable_cp));
> > > +		enable_cp.enable = LE_SCAN_DISABLE;
> > > +		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
> > > +			    &enable_cp);
> > > +	}
> > > +
> > >  	memset(&cp, 0, sizeof(cp));
> > >  	cp.scan_interval = cpu_to_le16(hdev->le_scan_interval);
> > >  	cp.scan_window = cpu_to_le16(hdev->le_scan_window);
> > 
> > The way this all hangs together with a discovery process started through
> > mgmt_start_discovery feels a bit flimsy to me. Particularly, have you
> > ensured that everything is fine if you've got inquiry ongoing when you
> > do hci_discovery_set_state(hdev, DISCOVERY_STOPPED). Also, are there any
> > risks of race conditions here, e.g. is it fine to let the
> > cancel_delayed_work() call be in create_le_conn_complete() instead of
> > doing it in hci_create_le_conn()?
> 
> Yes, I did lots of testing, including the inquiry test you mentioned,
> and I didn't find any issues.
> 
> I failed to see any race conditons since cancel_delayed_work() does not
> block. So it is fine to call cancel_delayed_work() in
> create_le_conn_complete() as well as in hci_create_le_conn().

I presume you'd want to prevent the delayed work from getting called as
soon as you've entered the if (test_bit(HCI_LE_SCAN)) section in
hci_create_le_conn? In theory it might get called before
create_le_conn_complete. In such a scenario
le_scan_disable_work_complete could e.g. trigger inquiry before
create_le_conn_complete is called, couldn't it?

> > What also makes this hard to track is that the condition you're testing
> > for first is the HCI_LE_SCAN bit, but then later you look at
> > discovery.state == DISCOVERY_FINDING. For the casual reader there's no
> > direct indication of how these two are releated for the various types of
> > discovery that are possible (LE-only, BR/EDR-only and interleaved).
> 
> Yes, I see your point. However, we can't check HCI_LE_SCAN in
> create_le_conn_complete() because the flag was already cleared in
> hci_cc_le_set_scan_enable().

Understood.

> > I don't mean to say that this is a nack for the patch, but I'd like to
> > know that you've considered and tested this kind of cases. I had to
> > spend quite some time looking through the existing code and this patch
> > and still couldn't arrive at absolute confidence of its correctness,
> > meaning there should hopefully be some room for simplification.
> 
> So I think we can do some simplification by moving this discovery
> handling from create_le_conn_complete() to hci_create_le_conn(), at
> least I think this code will become a bit easier to follow. What do you
> think?

I think it would at least close the potential race I described above,
i.e. the delayed work getting triggered before create_le_conn_complete.

Johan

Re: [RFC v4 05/12] Bluetooth: Stop scanning on LE connection

[Andre Guedes]

Hi Johan,

On Wed, 2013-12-18 at 13:11 +0200, Johan Hedberg wrote:
> Hi Andre,
> 
> On Tue, Dec 17, 2013, Andre Guedes wrote:
> > > > @@ -518,8 +518,17 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
> > > >  {
> > > >  	struct hci_conn *conn;
> > > >  
> > > > -	if (status == 0)
> > > > +	if (status == 0) {
> > > > +		/* If the discovery procedure was running, we prematurely
> > > > +		 * stopped it. So we have to change the discovery state.
> > > > +		 */
> > > > +		if (hdev->discovery.state == DISCOVERY_FINDING) {
> > > > +			cancel_delayed_work(&hdev->le_scan_disable);
> > > > +			hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
> > > > +		}
> > > > +
> > > >  		return;
> > > > +	}
> > > >  
> > > >  	BT_ERR("HCI request failed to create LE connection: status 0x%2.2x",
> > > >  	       status);
> > > > @@ -552,6 +561,18 @@ static int hci_create_le_conn(struct hci_conn *conn)
> > > >  
> > > >  	hci_req_init(&req, hdev);
> > > >  
> > > > +	/* If controller is scanning, we stop it since some controllers are
> > > > +	 * not able to scan and connect at the same time.
> > > > +	 */
> > > > +	if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
> > > > +		struct hci_cp_le_set_scan_enable enable_cp;
> > > > +
> > > > +		memset(&enable_cp, 0, sizeof(enable_cp));
> > > > +		enable_cp.enable = LE_SCAN_DISABLE;
> > > > +		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
> > > > +			    &enable_cp);
> > > > +	}
> > > > +
> > > >  	memset(&cp, 0, sizeof(cp));
> > > >  	cp.scan_interval = cpu_to_le16(hdev->le_scan_interval);
> > > >  	cp.scan_window = cpu_to_le16(hdev->le_scan_window);
> > > 
> > > The way this all hangs together with a discovery process started through
> > > mgmt_start_discovery feels a bit flimsy to me. Particularly, have you
> > > ensured that everything is fine if you've got inquiry ongoing when you
> > > do hci_discovery_set_state(hdev, DISCOVERY_STOPPED). Also, are there any
> > > risks of race conditions here, e.g. is it fine to let the
> > > cancel_delayed_work() call be in create_le_conn_complete() instead of
> > > doing it in hci_create_le_conn()?
> > 
> > Yes, I did lots of testing, including the inquiry test you mentioned,
> > and I didn't find any issues.
> > 
> > I failed to see any race conditons since cancel_delayed_work() does not
> > block. So it is fine to call cancel_delayed_work() in
> > create_le_conn_complete() as well as in hci_create_le_conn().
> 
> I presume you'd want to prevent the delayed work from getting called as
> soon as you've entered the if (test_bit(HCI_LE_SCAN)) section in
> hci_create_le_conn? In theory it might get called before
> create_le_conn_complete. In such a scenario
> le_scan_disable_work_complete could e.g. trigger inquiry before
> create_le_conn_complete is called, couldn't it?

Yes, this scenario can indeed happen in a very short window. However, it
doesn't seem to be a big issue. If that happen then the discovery
procedure keeps running normally and the connection attempt fails. If it
is a auto connection then the kernel will retry in a near future. If it
a user connection, it will get a busy error.   

> > > What also makes this hard to track is that the condition you're testing
> > > for first is the HCI_LE_SCAN bit, but then later you look at
> > > discovery.state == DISCOVERY_FINDING. For the casual reader there's no
> > > direct indication of how these two are releated for the various types of
> > > discovery that are possible (LE-only, BR/EDR-only and interleaved).
> > 
> > Yes, I see your point. However, we can't check HCI_LE_SCAN in
> > create_le_conn_complete() because the flag was already cleared in
> > hci_cc_le_set_scan_enable().
> 
> Understood.
> 
> > > I don't mean to say that this is a nack for the patch, but I'd like to
> > > know that you've considered and tested this kind of cases. I had to
> > > spend quite some time looking through the existing code and this patch
> > > and still couldn't arrive at absolute confidence of its correctness,
> > > meaning there should hopefully be some room for simplification.
> > 
> > So I think we can do some simplification by moving this discovery
> > handling from create_le_conn_complete() to hci_create_le_conn(), at
> > least I think this code will become a bit easier to follow. What do you
> > think?
> 
> I think it would at least close the potential race I described above,
> i.e. the delayed work getting triggered before create_le_conn_complete.

I realized this approach is not good enough since we'll be changing
discovery state before being sure the HCI command executed successfully.
This could let the discovery state inconsistent.

So after spending some time thinking about this issue, I believe the
better way to handle this is taking it in two steps. First, we simply
stop scanning and handle the discovery state. Then we create the LE
connection.

I'm already working on this "two steps" approach and I should send the
v5 patch set very soon.

Regards,

Andre

[RFC v4 06/12] Bluetooth: Introduce hdev->pend_le_conn list

[Andre Guedes]

This patch introduces the hdev->pend_le_conn list which holds the
device addresses the kernel should autonomously connect. It also
introduces some helper functions to manipulate the list.

The list and helper functions will be used by the next patch which
implements the LE auto connection infrastructure.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 include/net/bluetooth/hci_core.h |  7 +++++
 net/bluetooth/hci_core.c         | 68 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index a35b90d..b85501d 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -268,6 +268,7 @@ struct hci_dev {
 	struct list_head	long_term_keys;
 	struct list_head	remote_oob_data;
 	struct list_head	le_conn_params;
+	struct list_head	pend_le_conns;
 
 	struct hci_dev_stats	stat;
 
@@ -764,6 +765,12 @@ void hci_conn_params_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type,
 void hci_conn_params_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
 void hci_conn_params_clear(struct hci_dev *hdev);
 
+struct bdaddr_list *hci_pend_le_conn_lookup(struct hci_dev *hdev,
+					    bdaddr_t *addr, u8 addr_type);
+void hci_pend_le_conn_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
+void hci_pend_le_conn_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
+void hci_pend_le_conns_clear(struct hci_dev *hdev);
+
 int hci_uuids_clear(struct hci_dev *hdev);
 
 int hci_link_keys_clear(struct hci_dev *hdev);
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index dd9a25c..05e6073 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2851,6 +2851,72 @@ void hci_conn_params_clear(struct hci_dev *hdev)
 	BT_DBG("All LE connection parameters were removed");
 }
 
+/* This function requires the caller holds hdev->lock */
+struct bdaddr_list *hci_pend_le_conn_lookup(struct hci_dev *hdev,
+					    bdaddr_t *addr, u8 addr_type)
+{
+	struct bdaddr_list *entry;
+
+	list_for_each_entry(entry, &hdev->pend_le_conns, list) {
+		if (bacmp(&entry->bdaddr, addr) == 0 &&
+		    entry->bdaddr_type == addr_type)
+			return entry;
+	}
+
+	return NULL;
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_pend_le_conn_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
+{
+	struct bdaddr_list *entry;
+
+	entry = hci_pend_le_conn_lookup(hdev, addr, addr_type);
+	if (entry)
+		return;
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		BT_ERR("Out of memory");
+		return;
+	}
+
+	bacpy(&entry->bdaddr, addr);
+	entry->bdaddr_type = addr_type;
+
+	list_add(&entry->list, &hdev->pend_le_conns);
+
+	BT_DBG("addr %pMR (type %u)", addr, addr_type);
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_pend_le_conn_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
+{
+	struct bdaddr_list *entry;
+
+	entry = hci_pend_le_conn_lookup(hdev, addr, addr_type);
+	if (!entry)
+		return;
+
+	list_del(&entry->list);
+	kfree(entry);
+
+	BT_DBG("addr %pMR (type %u)", addr, addr_type);
+}
+
+/* This function requires the caller holds hdev->lock */
+void hci_pend_le_conns_clear(struct hci_dev *hdev)
+{
+	struct bdaddr_list *entry, *tmp;
+
+	list_for_each_entry_safe(entry, tmp, &hdev->pend_le_conns, list) {
+		list_del(&entry->list);
+		kfree(entry);
+	}
+
+	BT_DBG("All LE pending connections cleared");
+}
+
 static void inquiry_complete(struct hci_dev *hdev, u8 status)
 {
 	if (status) {
@@ -2962,6 +3028,7 @@ struct hci_dev *hci_alloc_dev(void)
 	INIT_LIST_HEAD(&hdev->long_term_keys);
 	INIT_LIST_HEAD(&hdev->remote_oob_data);
 	INIT_LIST_HEAD(&hdev->le_conn_params);
+	INIT_LIST_HEAD(&hdev->pend_le_conns);
 	INIT_LIST_HEAD(&hdev->conn_hash.list);
 
 	INIT_WORK(&hdev->rx_work, hci_rx_work);
@@ -3148,6 +3215,7 @@ void hci_unregister_dev(struct hci_dev *hdev)
 	hci_smp_ltks_clear(hdev);
 	hci_remote_oob_data_clear(hdev);
 	hci_conn_params_clear(hdev);
+	hci_pend_le_conns_clear(hdev);
 	hci_dev_unlock(hdev);
 
 	hci_dev_put(hdev);
-- 
1.8.4.2

[RFC v4 07/12] Bluetooth: Introduce LE auto connection infrastructure

[Andre Guedes]

This patch introduces the LE auto connection infrastructure.
This infrastructure will be used to implement the auto_connect
options from hci_conn_params.

In summary, the auto connection mechanism works as follows: Once the
first pending LE connection is created, the background scanning is
started. When the target device is found in range, the kernel
autonomously starts the connection attempt. If connection is
established successfully, that pending LE connection is deleted and
the background is stopped.

To achieve that, this patch introduces the hci_update_background_scan()
which controls the background scanning state. This function starts or
stops the background scanning based on the hdev->pend_le_conns list. If
there is no pending LE connection, the background scanning is stopped.
Otherwise, we start the background scanning.

Then, every time a pending LE connection is added we call hci_update_
background_scan() so the background scanning is started (in case it is
not already running). Likewise, every time a pending LE connection is
deleted we call hci_update_background_scan() so the background scanning
is stopped (in case this was the last pending LE connection) or it is
started again (in case we have more pending LE connections). This way
the background scanning keeps running until all pending LE connection
are established.

When a device with pending connection is in range, we establish the
connection and delete the pending connection.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 include/net/bluetooth/hci_core.h |  2 +
 net/bluetooth/hci_core.c         | 86 +++++++++++++++++++++++++++++++++++++++-
 net/bluetooth/hci_event.c        | 41 +++++++++++++++++++
 3 files changed, 127 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index b85501d..72dc8f5 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -771,6 +771,8 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
 void hci_pend_le_conn_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
 void hci_pend_le_conns_clear(struct hci_dev *hdev);
 
+void hci_update_background_scan(struct hci_dev *hdev);
+
 int hci_uuids_clear(struct hci_dev *hdev);
 
 int hci_link_keys_clear(struct hci_dev *hdev);
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 05e6073..47d31bd 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2873,7 +2873,7 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
 
 	entry = hci_pend_le_conn_lookup(hdev, addr, addr_type);
 	if (entry)
-		return;
+		goto done;
 
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
@@ -2887,6 +2887,9 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
 	list_add(&entry->list, &hdev->pend_le_conns);
 
 	BT_DBG("addr %pMR (type %u)", addr, addr_type);
+
+done:
+	hci_update_background_scan(hdev);
 }
 
 /* This function requires the caller holds hdev->lock */
@@ -2896,12 +2899,15 @@ void hci_pend_le_conn_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type)
 
 	entry = hci_pend_le_conn_lookup(hdev, addr, addr_type);
 	if (!entry)
-		return;
+		goto done;
 
 	list_del(&entry->list);
 	kfree(entry);
 
 	BT_DBG("addr %pMR (type %u)", addr, addr_type);
+
+done:
+	hci_update_background_scan(hdev);
 }
 
 /* This function requires the caller holds hdev->lock */
@@ -4443,3 +4449,79 @@ static void hci_cmd_work(struct work_struct *work)
 		}
 	}
 }
+
+static void update_background_scan_complete(struct hci_dev *hdev, u8 status)
+{
+	if (status)
+		BT_DBG("HCI request failed to update background scanning: "
+		       "status 0x%2.2x", status);
+}
+
+/* This function controls the background scanning based on hdev->pend_le_conns
+ * list. If there are pending LE connection we start the background scanning,
+ * otherwise we stop it.
+ *
+ * This function requires the caller holds hdev->lock.
+ */
+void hci_update_background_scan(struct hci_dev *hdev)
+{
+	struct hci_cp_le_set_scan_param param_cp;
+	struct hci_cp_le_set_scan_enable enable_cp;
+	struct hci_request req;
+	struct hci_conn *conn;
+	int err;
+
+	hci_req_init(&req, hdev);
+
+	if (list_empty(&hdev->pend_le_conns)) {
+		/* If there is no pending LE connections, we should stop
+		 * the background scanning.
+		 */
+
+		/* If controller is not scanning we are done. */
+		if (!test_bit(HCI_LE_SCAN, &hdev->dev_flags))
+			return;
+
+		memset(&enable_cp, 0, sizeof(enable_cp));
+		enable_cp.enable = LE_SCAN_DISABLE;
+		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
+			    &enable_cp);
+
+		BT_DBG("%s stopping background scanning", hdev->name);
+	} else {
+		/* If there is at least one pending LE connection, we should
+		 * keep the background scan running.
+		 */
+
+		/* If controller is already scanning we are done. */
+		if (test_bit(HCI_LE_SCAN, &hdev->dev_flags))
+			return;
+
+		/* If controller is connecting, we should not start scanning
+		 * since some controllers are not able to scan and connect at
+		 * the same time.
+		 */
+		conn = hci_conn_hash_lookup_state(hdev, LE_LINK, BT_CONNECT);
+		if (conn)
+			return;
+
+		memset(&param_cp, 0, sizeof(param_cp));
+		param_cp.type = LE_SCAN_PASSIVE;
+		param_cp.interval = cpu_to_le16(hdev->le_scan_interval);
+		param_cp.window = cpu_to_le16(hdev->le_scan_window);
+		hci_req_add(&req, HCI_OP_LE_SET_SCAN_PARAM, sizeof(param_cp),
+			    &param_cp);
+
+		memset(&enable_cp, 0, sizeof(enable_cp));
+		enable_cp.enable = LE_SCAN_ENABLE;
+		enable_cp.filter_dup = LE_SCAN_FILTER_DUP_DISABLE;
+		hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
+			    &enable_cp);
+
+		BT_DBG("%s starting background scanning", hdev->name);
+	}
+
+	err = hci_req_run(&req, update_background_scan_complete);
+	if (err)
+		BT_ERR("Failed to run HCI request: err %d", err);
+}
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 5fb3df6..60ca708 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3537,25 +3537,66 @@ static void hci_le_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 
 	hci_proto_connect_cfm(conn, ev->status);
 
+	hci_pend_le_conn_del(hdev, &ev->bdaddr, ev->bdaddr_type);
+
 unlock:
 	hci_dev_unlock(hdev);
 }
 
+/* This function requires the caller holds hdev->lock */
+static void check_pending_le_conn(struct hci_dev *hdev, bdaddr_t *addr,
+				  u8 addr_type)
+{
+	struct hci_conn *conn;
+	u8 bdaddr_type;
+
+	if (!hci_pend_le_conn_lookup(hdev, addr, addr_type))
+		return;
+
+	if (addr_type == ADDR_LE_DEV_PUBLIC)
+		bdaddr_type = BDADDR_LE_PUBLIC;
+	else
+		bdaddr_type = BDADDR_LE_RANDOM;
+
+	conn = hci_connect(hdev, LE_LINK, addr, bdaddr_type, BT_SECURITY_LOW,
+			   HCI_AT_NO_BONDING);
+	if (!IS_ERR(conn))
+		return;
+
+	switch (PTR_ERR(conn)) {
+	case -EBUSY:
+		/* If hci_connect() returns -EBUSY it means there is already
+		 * an LE connection attempt going on. Since controllers don't
+		 * support more than one connection attempt at the time, we
+		 * don't consider this an error case.
+		 */
+		break;
+	default:
+		BT_ERR("Failed to connect: err %ld", PTR_ERR(conn));
+	}
+}
+
 static void hci_le_adv_report_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	u8 num_reports = skb->data[0];
 	void *ptr = &skb->data[1];
 	s8 rssi;
 
+	hci_dev_lock(hdev);
+
 	while (num_reports--) {
 		struct hci_ev_le_advertising_info *ev = ptr;
 
+		check_pending_le_conn(hdev, &ev->bdaddr, ev->bdaddr_type);
+
 		rssi = ev->data[ev->length];
 		mgmt_device_found(hdev, &ev->bdaddr, LE_LINK, ev->bdaddr_type,
 				  NULL, rssi, 0, 1, ev->data, ev->length);
 
 		ptr += sizeof(*ev) + ev->length + 1;
 	}
+
+	hci_dev_unlock(hdev);
 }
 
 static void hci_le_ltk_request_evt(struct hci_dev *hdev, struct sk_buff *skb)
-- 
1.8.4.2

[RFC v4 08/12] Bluetooth: Re-enable background scan in case of error

[Andre Guedes]

Since we temporarily stop the background scanning in favor of
connection, we should re-enable it in case something goes wrong
with connection establishment. So this patch adds a hci_update_
background_scan() call in create_le_conn_complete() and hci_le_
conn_complete_evt() error flow.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_conn.c  | 2 ++
 net/bluetooth/hci_event.c | 1 +
 2 files changed, 3 insertions(+)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 750a39d..2ca34fa 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -548,6 +548,8 @@ static void create_le_conn_complete(struct hci_dev *hdev, u8 status)
 
 	hci_conn_del(conn);
 
+	hci_update_background_scan(hdev);
+
 done:
 	hci_dev_unlock(hdev);
 }
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 60ca708..e4f288a 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3522,6 +3522,7 @@ static void hci_le_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 		hci_proto_connect_cfm(conn, ev->status);
 		conn->state = BT_CLOSED;
 		hci_conn_del(conn);
+		hci_update_background_scan(hdev);
 		goto unlock;
 	}
 
-- 
1.8.4.2

[RFC v4 09/12] Bluetooth: Temporarily stop background scanning on discovery

[Andre Guedes]

If the user send a mgmt start discovery command while the background
scanning is running, we should temporarily stop it. Once the discovery
finishes, we start the background scanning again.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_core.c |  2 ++
 net/bluetooth/mgmt.c     | 12 ++++++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 47d31bd..5bb73cf 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1498,6 +1498,8 @@ void hci_discovery_set_state(struct hci_dev *hdev, int state)
 
 	switch (state) {
 	case DISCOVERY_STOPPED:
+		hci_update_background_scan(hdev);
+
 		if (hdev->discovery.state != DISCOVERY_STARTING)
 			mgmt_discovering(hdev, 0);
 		break;
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index a03ca3c..81b8cfa 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -3280,11 +3280,15 @@ static int start_discovery(struct sock *sk, struct hci_dev *hdev,
 			goto failed;
 		}
 
+		/* If controller is scanning, it means the background scanning
+		 * is running. Thus, we should temporarily stop it in order to
+		 * set the discovery scanning parameters.
+		 */
 		if (test_bit(HCI_LE_SCAN, &hdev->dev_flags)) {
-			err = cmd_status(sk, hdev->id, MGMT_OP_START_DISCOVERY,
-					 MGMT_STATUS_BUSY);
-			mgmt_pending_remove(cmd);
-			goto failed;
+			memset(&enable_cp, 0, sizeof(enable_cp));
+			enable_cp.enable = LE_SCAN_DISABLE;
+			hci_req_add(&req, HCI_OP_LE_SET_SCAN_ENABLE,
+				    sizeof(enable_cp), &enable_cp);
 		}
 
 		memset(&param_cp, 0, sizeof(param_cp));
-- 
1.8.4.2

[RFC v4 10/12] Bluetooth: Auto connection and power on

[Andre Guedes]

When hdev is closed (e.g. Mgmt power off command, RFKILL or controller
is reset), the ongoing active connections are silently dropped by the
controller (no Disconnection Complete Event is sent to host). For that
reason, the devices that require HCI_AUTO_CONN_ALWAYS are not added to
hdev->pend_le_conns list and they won't auto connect.

So to fix this issue, during hdev closing, we remove all pending LE
connections. After adapter is powered on, we add a pending LE connection
for each HCI_AUTO_CONN_ALWAYS address.

This way, the auto connection mechanism works propely after a power
off and power on sequence as well as RFKILL block/unblock.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_core.c |  1 +
 net/bluetooth/mgmt.c     | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 5bb73cf..beb51ce 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1969,6 +1969,7 @@ static int hci_dev_do_close(struct hci_dev *hdev)
 	hci_dev_lock(hdev);
 	hci_inquiry_cache_flush(hdev);
 	hci_conn_hash_flush(hdev);
+	hci_pend_le_conns_clear(hdev);
 	hci_dev_unlock(hdev);
 
 	hci_notify(hdev, HCI_DEV_DOWN);
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 81b8cfa..3fccb52 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -4247,6 +4247,17 @@ void mgmt_index_removed(struct hci_dev *hdev)
 	mgmt_event(MGMT_EV_INDEX_REMOVED, hdev, NULL, 0, NULL);
 }
 
+/* This function requires the caller holds hdev->lock */
+static void restart_le_auto_conns(struct hci_dev *hdev)
+{
+	struct hci_conn_params *p;
+
+	list_for_each_entry(p, &hdev->le_conn_params, list) {
+		if (p->auto_connect == HCI_AUTO_CONN_ALWAYS)
+			hci_pend_le_conn_add(hdev, &p->addr, p->addr_type);
+	}
+}
+
 static void powered_complete(struct hci_dev *hdev, u8 status)
 {
 	struct cmd_lookup match = { NULL, hdev };
@@ -4255,6 +4266,8 @@ static void powered_complete(struct hci_dev *hdev, u8 status)
 
 	hci_dev_lock(hdev);
 
+	restart_le_auto_conns(hdev);
+
 	mgmt_pending_foreach(MGMT_OP_SET_POWERED, hdev, settings_rsp, &match);
 
 	new_settings(hdev, match.sk);
-- 
1.8.4.2

[RFC v4 11/12] Bleutooth: Add support for auto connect options

[Andre Guedes]

This patch adds support for the HCI_AUTO_CONN_ALWAYS and HCI_AUTO_
CONN_LINK_LOSS options from struct hci_conn_params.

The HCI_AUTO_CONN_ALWAYS option configures the kernel to always re-
establish the connection, no matter the reason the connection was
terminated. This feature is required by some LE profiles such as
HID over GATT, Health Thermometer and Blood Pressure. These profiles
require the host autonomously connect to the device as soon as it
enters in connectable mode (start advertising) so the device is able
to delivery notifications or indications.

The BT_AUTO_CONN_LINK_LOSS option configures the kernel to re-
establish the connection in case the connection was terminated due
to a link loss. This feature is required by the majority of LE
profiles such as Proximity, Find Me, Cycling Speed and Cadence and
Time.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_event.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index e4f288a..a4ce922 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -1780,6 +1780,7 @@ static void hci_disconn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 {
 	struct hci_ev_disconn_complete *ev = (void *) skb->data;
 	u8 reason = hci_to_mgmt_reason(ev->reason);
+	struct hci_conn_params *params;
 	struct hci_conn *conn;
 	u8 type;
 
@@ -1806,6 +1807,23 @@ static void hci_disconn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
 	if (conn->type == ACL_LINK && conn->flush_key)
 		hci_remove_link_key(hdev, &conn->dst);
 
+	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
+	if (params) {
+		switch (params->auto_connect) {
+		case HCI_AUTO_CONN_LINK_LOSS:
+			if (ev->reason != HCI_ERROR_CONNECTION_TIMEOUT)
+				break;
+			/* Fall through */
+
+		case HCI_AUTO_CONN_ALWAYS:
+			hci_pend_le_conn_add(hdev, &conn->dst, conn->dst_type);
+			break;
+
+		default:
+			break;
+		}
+	}
+
 	type = conn->type;
 
 	hci_proto_disconn_cfm(conn, ev->reason);
-- 
1.8.4.2

[RFC v4 12/12] Bluetooth: Add le_auto_conn file on debugfs

[Andre Guedes]

This patch adds to debugfs the le_auto_conn file. This file will be
used to test LE auto connection infrastructure.

To add a new auto connection address we write on le_auto_conn file
following the format <address> <address type> <auto_connect>.

The <address type> values are:
  * 0 for public address
  * 1 for random address

The <auto_connect> values are (for more details see struct hci_
conn_params):
  * 0 for disabled
  * 1 for always
  * 2 for link loss

So for instance, if you want the kernel autonomously establishes
connections with device AA:BB:CC:DD:EE:FF (public address) every
time the device enters in connectable mode (starts advertising),
you should run the command:
$ echo "AA:BB:CC:DD:EE:FF 0 1" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

To get the list of connection parameters configured in kernel, read
the le_auto_conn file:
$ cat /sys/kernel/debug/bluetooth/hci0/le_auto_conn

Finally, to clear the connection parameters list, write an empty
string:
$ echo "" > /sys/kernel/debug/bluetooth/hci0/le_auto_conn

This file is created only if LE is enabled.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
---
 net/bluetooth/hci_core.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index beb51ce..be7da12 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -636,6 +636,89 @@ static int conn_max_interval_get(void *data, u64 *val)
 DEFINE_SIMPLE_ATTRIBUTE(conn_max_interval_fops, conn_max_interval_get,
 			conn_max_interval_set, "%llu\n");
 
+static int le_auto_conn_show(struct seq_file *sf, void *ptr)
+{
+	struct hci_dev *hdev = sf->private;
+	struct hci_conn_params *p;
+
+	hci_dev_lock(hdev);
+
+	list_for_each_entry(p, &hdev->le_conn_params, list) {
+		seq_printf(sf, "%pMR %u %u\n", &p->addr, p->addr_type,
+			   p->auto_connect);
+	}
+
+	hci_dev_unlock(hdev);
+
+	return 0;
+}
+
+static int le_auto_conn_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, le_auto_conn_show, inode->i_private);
+}
+
+static ssize_t le_auto_conn_write(struct file *file, const char __user *data,
+				  size_t count, loff_t *offset)
+{
+	struct seq_file *sf = file->private_data;
+	struct hci_dev *hdev = sf->private;
+	u8 auto_connect;
+	bdaddr_t addr;
+	u8 addr_type;
+	char *buf;
+	int n;
+
+	/* Don't allow partial write */
+	if (*offset != 0)
+		return -EINVAL;
+
+	/* If empty string, clear the connection parameters and pending LE
+	 * connection list.
+	 */
+	if (count == 1) {
+		hci_dev_lock(hdev);
+		hci_conn_params_clear(hdev);
+		hci_pend_le_conns_clear(hdev);
+		hci_dev_unlock(hdev);
+		return count;
+	}
+
+	buf = kzalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, data, count)) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	n = sscanf(buf, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx %hhu %hhu", &addr.b[5],
+		   &addr.b[4], &addr.b[3], &addr.b[2], &addr.b[1], &addr.b[0],
+		   &addr_type, &auto_connect);
+	if (n != 8) {
+		kfree(buf);
+		return -EINVAL;
+	}
+
+	hci_dev_lock(hdev);
+	hci_conn_params_add(hdev, &addr, addr_type, auto_connect,
+			    hdev->le_conn_min_interval,
+			    hdev->le_conn_max_interval);
+	hci_dev_unlock(hdev);
+
+	kfree(buf);
+	return count;
+}
+
+static const struct file_operations le_auto_conn_fops = {
+	.open		= le_auto_conn_open,
+	.read		= seq_read,
+	.write		= le_auto_conn_write,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
 /* ---- HCI requests ---- */
 
 static void hci_req_sync_complete(struct hci_dev *hdev, u8 result)
@@ -1406,6 +1489,8 @@ static int __hci_init(struct hci_dev *hdev)
 				    hdev, &conn_min_interval_fops);
 		debugfs_create_file("conn_max_interval", 0644, hdev->debugfs,
 				    hdev, &conn_max_interval_fops);
+		debugfs_create_file("le_auto_conn", 0644, hdev->debugfs, hdev,
+				    &le_auto_conn_fops);
 	}
 
 	return 0;
-- 
1.8.4.2