[PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[Jonas Dreßler]

Since commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
requests"), the kernel supports trying to connect again in case the
bluetooth card is busy and fails to connect.

The logic that should handle this became a bit spotty over time, and also
cards these days appear to fail with more errors than just "Command
Disallowed".

This series refactores the handling of concurrent connection requests
by serializing all "Create Connection" commands for ACL connections
similar to how we do it for LE connections.

---

v1: https://lore.kernel.org/linux-bluetooth/20240102185933.64179-1-verdre@v0yd.nl/
v2: https://lore.kernel.org/linux-bluetooth/20240108183938.468426-1-verdre@v0yd.nl/
v3: https://lore.kernel.org/linux-bluetooth/20240108224614.56900-1-verdre@v0yd.nl/
v4:
  - Removed first two commits since they are already applied
  - Removed a BT_DBG() message in the acl_create_connection() function
    while moving to hci_sync because it seemed out of place in hci_sync
  - Added a mention of the test failure in mgmt-tester to commit message

Jonas Dreßler (2):
  Bluetooth: hci_conn: Only do ACL connections sequentially
  Bluetooth: Remove pending ACL connection attempts

 include/net/bluetooth/hci.h      |  1 +
 include/net/bluetooth/hci_core.h |  1 -
 include/net/bluetooth/hci_sync.h |  3 ++
 net/bluetooth/hci_conn.c         | 83 +++-----------------------------
 net/bluetooth/hci_event.c        | 21 ++------
 net/bluetooth/hci_sync.c         | 70 +++++++++++++++++++++++++++
 6 files changed, 86 insertions(+), 93 deletions(-)

-- 
2.43.0

[PATCH v4 1/2] Bluetooth: hci_conn: Only do ACL connections sequentially

[Jonas Dreßler]

Pretty much all bluetooth chipsets only support paging a single device at
a time, and if they don't reject a secondary "Create Connection" request
while another is still ongoing, they'll most likely serialize those
requests in the firware.

With commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
requests") we started adding some serialization of our own in case the
adapter returns "Command Disallowed" HCI error.

This commit was using the BT_CONNECT2 state for the serialization, this
state is also used for a few more things (most notably to indicate we're
waiting for an inquiry to cancel) and therefore a bit unreliable. Also
not all BT firwares would respond with "Command Disallowed" on too many
connection requests, some will also respond with "Hardware Failure"
(BCM4378), and others will error out later and send a "Connect Complete"
event with error "Rejected Limited Resources" (Marvell 88W8897).

We can clean things up a bit and also make the serialization more reliable
by using our hci_sync machinery to always do "Create Connection" requests
in a sequential manner.

This is very similar to what we're already doing for establishing LE
connections, and it works well there.

Note that this causes a test failure in mgmt-tester (test "Pair Device
- Power off 1") because the hci_abort_conn_sync() changes the error we
return on timeout of the "Create Connection". We'll fix this on the
mgmt-tester side by adjusting the expected error for the test.
---
 include/net/bluetooth/hci.h      |  1 +
 include/net/bluetooth/hci_sync.h |  3 ++
 net/bluetooth/hci_conn.c         | 69 ++++---------------------------
 net/bluetooth/hci_sync.c         | 70 ++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+), 60 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index aa6c69053d..08cb5cb249 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -437,6 +437,7 @@ enum {
 #define HCI_NCMD_TIMEOUT	msecs_to_jiffies(4000)	/* 4 seconds */
 #define HCI_ACL_TX_TIMEOUT	msecs_to_jiffies(45000)	/* 45 seconds */
 #define HCI_AUTO_OFF_TIMEOUT	msecs_to_jiffies(2000)	/* 2 seconds */
+#define HCI_ACL_CONN_TIMEOUT	msecs_to_jiffies(20000)	/* 20 seconds */
 #define HCI_LE_CONN_TIMEOUT	msecs_to_jiffies(20000)	/* 20 seconds */
 #define HCI_LE_AUTOCONN_TIMEOUT	msecs_to_jiffies(4000)	/* 4 seconds */
 
diff --git a/include/net/bluetooth/hci_sync.h b/include/net/bluetooth/hci_sync.h
index e2582c2425..824660f8f3 100644
--- a/include/net/bluetooth/hci_sync.h
+++ b/include/net/bluetooth/hci_sync.h
@@ -138,3 +138,6 @@ int hci_le_terminate_big_sync(struct hci_dev *hdev, u8 handle, u8 reason);
 int hci_le_big_terminate_sync(struct hci_dev *hdev, u8 handle);
 
 int hci_le_pa_terminate_sync(struct hci_dev *hdev, u16 handle);
+
+int hci_acl_create_connection_sync(struct hci_dev *hdev,
+				   struct hci_conn *conn);
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fc4d72f83a..816be7667a 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -178,64 +178,6 @@ static void hci_conn_cleanup(struct hci_conn *conn)
 	hci_dev_put(hdev);
 }
 
-static void hci_acl_create_connection(struct hci_conn *conn)
-{
-	struct hci_dev *hdev = conn->hdev;
-	struct inquiry_entry *ie;
-	struct hci_cp_create_conn cp;
-
-	BT_DBG("hcon %p", conn);
-
-	/* Many controllers disallow HCI Create Connection while it is doing
-	 * HCI Inquiry. So we cancel the Inquiry first before issuing HCI Create
-	 * Connection. This may cause the MGMT discovering state to become false
-	 * without user space's request but it is okay since the MGMT Discovery
-	 * APIs do not promise that discovery should be done forever. Instead,
-	 * the user space monitors the status of MGMT discovering and it may
-	 * request for discovery again when this flag becomes false.
-	 */
-	if (test_bit(HCI_INQUIRY, &hdev->flags)) {
-		/* Put this connection to "pending" state so that it will be
-		 * executed after the inquiry cancel command complete event.
-		 */
-		conn->state = BT_CONNECT2;
-		hci_send_cmd(hdev, HCI_OP_INQUIRY_CANCEL, 0, NULL);
-		return;
-	}
-
-	conn->state = BT_CONNECT;
-	conn->out = true;
-	conn->role = HCI_ROLE_MASTER;
-
-	conn->attempt++;
-
-	conn->link_policy = hdev->link_policy;
-
-	memset(&cp, 0, sizeof(cp));
-	bacpy(&cp.bdaddr, &conn->dst);
-	cp.pscan_rep_mode = 0x02;
-
-	ie = hci_inquiry_cache_lookup(hdev, &conn->dst);
-	if (ie) {
-		if (inquiry_entry_age(ie) <= INQUIRY_ENTRY_AGE_MAX) {
-			cp.pscan_rep_mode = ie->data.pscan_rep_mode;
-			cp.pscan_mode     = ie->data.pscan_mode;
-			cp.clock_offset   = ie->data.clock_offset |
-					    cpu_to_le16(0x8000);
-		}
-
-		memcpy(conn->dev_class, ie->data.dev_class, 3);
-	}
-
-	cp.pkt_type = cpu_to_le16(conn->pkt_type);
-	if (lmp_rswitch_capable(hdev) && !(hdev->link_mode & HCI_LM_MASTER))
-		cp.role_switch = 0x01;
-	else
-		cp.role_switch = 0x00;
-
-	hci_send_cmd(hdev, HCI_OP_CREATE_CONN, sizeof(cp), &cp);
-}
-
 int hci_disconnect(struct hci_conn *conn, __u8 reason)
 {
 	BT_DBG("hcon %p", conn);
@@ -1696,10 +1638,17 @@ struct hci_conn *hci_connect_acl(struct hci_dev *hdev, bdaddr_t *dst,
 
 	acl->conn_reason = conn_reason;
 	if (acl->state == BT_OPEN || acl->state == BT_CLOSED) {
+		int err;
+
 		acl->sec_level = BT_SECURITY_LOW;
 		acl->pending_sec_level = sec_level;
 		acl->auth_type = auth_type;
-		hci_acl_create_connection(acl);
+
+		err = hci_acl_create_connection_sync(hdev, acl);
+		if (err) {
+			hci_conn_del(acl);
+			return ERR_PTR(err);
+		}
 	}
 
 	return acl;
@@ -2654,7 +2603,7 @@ void hci_conn_check_pending(struct hci_dev *hdev)
 
 	conn = hci_conn_hash_lookup_state(hdev, ACL_LINK, BT_CONNECT2);
 	if (conn)
-		hci_acl_create_connection(conn);
+		hci_acl_create_connection_sync(hdev, conn);
 
 	hci_dev_unlock(hdev);
 }
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 1122296ce3..617407b81f 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -6492,3 +6492,73 @@ int hci_update_adv_data(struct hci_dev *hdev, u8 instance)
 	return hci_cmd_sync_queue(hdev, _update_adv_data_sync,
 				  UINT_PTR(instance), NULL);
 }
+
+static int __hci_acl_create_connection_sync(struct hci_dev *hdev, void *data)
+{
+	struct hci_conn *conn = data;
+	struct inquiry_entry *ie;
+	struct hci_cp_create_conn cp;
+	int err;
+
+	/* Many controllers disallow HCI Create Connection while it is doing
+	 * HCI Inquiry. So we cancel the Inquiry first before issuing HCI Create
+	 * Connection. This may cause the MGMT discovering state to become false
+	 * without user space's request but it is okay since the MGMT Discovery
+	 * APIs do not promise that discovery should be done forever. Instead,
+	 * the user space monitors the status of MGMT discovering and it may
+	 * request for discovery again when this flag becomes false.
+	 */
+	if (test_bit(HCI_INQUIRY, &hdev->flags)) {
+		err = __hci_cmd_sync_status(hdev, HCI_OP_INQUIRY_CANCEL, 0,
+					    NULL, HCI_CMD_TIMEOUT);
+		if (err)
+			bt_dev_warn(hdev, "Failed to cancel inquiry %d", err);
+	}
+
+	conn->state = BT_CONNECT;
+	conn->out = true;
+	conn->role = HCI_ROLE_MASTER;
+
+	conn->attempt++;
+
+	conn->link_policy = hdev->link_policy;
+
+	memset(&cp, 0, sizeof(cp));
+	bacpy(&cp.bdaddr, &conn->dst);
+	cp.pscan_rep_mode = 0x02;
+
+	ie = hci_inquiry_cache_lookup(hdev, &conn->dst);
+	if (ie) {
+		if (inquiry_entry_age(ie) <= INQUIRY_ENTRY_AGE_MAX) {
+			cp.pscan_rep_mode = ie->data.pscan_rep_mode;
+			cp.pscan_mode     = ie->data.pscan_mode;
+			cp.clock_offset   = ie->data.clock_offset |
+					    cpu_to_le16(0x8000);
+		}
+
+		memcpy(conn->dev_class, ie->data.dev_class, 3);
+	}
+
+	cp.pkt_type = cpu_to_le16(conn->pkt_type);
+	if (lmp_rswitch_capable(hdev) && !(hdev->link_mode & HCI_LM_MASTER))
+		cp.role_switch = 0x01;
+	else
+		cp.role_switch = 0x00;
+
+	err = __hci_cmd_sync_status_sk(hdev, HCI_OP_CREATE_CONN,
+				       sizeof(cp), &cp,
+				       HCI_EV_CONN_COMPLETE,
+				       HCI_ACL_CONN_TIMEOUT, NULL);
+
+	if (err == -ETIMEDOUT)
+		hci_abort_conn_sync(hdev, conn, HCI_ERROR_LOCAL_HOST_TERM);
+
+	return err;
+}
+
+int hci_acl_create_connection_sync(struct hci_dev *hdev,
+				   struct hci_conn *conn)
+{
+	return hci_cmd_sync_queue(hdev, __hci_acl_create_connection_sync,
+				  conn, NULL);
+}
-- 
2.43.0

[PATCH v4 2/2] Bluetooth: Remove pending ACL connection attempts

[Jonas Dreßler]

With the last commit we moved to using the hci_sync queue for "Create
Connection" requests, removing the need for retrying the paging after
finished/failed "Create Connection" requests and after the end of
inquiries.

hci_conn_check_pending() was used to trigger this retry, we can remove it
now.

Note that we can also remove the special handling for COMMAND_DISALLOWED
errors in the completion handler of "Create Connection", because "Create
Connection" requests are now always serialized.

This is somewhat reverting commit 4c67bc74f016 ("[Bluetooth] Support
concurrent connect requests").

With this, the BT_CONNECT2 state of ACL hci_conn objects should now be
back to meaning only one thing: That we received a "Connection Request"
from another device (see hci_conn_request_evt), but the response to that
is going to be deferred.
---
 include/net/bluetooth/hci_core.h |  1 -
 net/bluetooth/hci_conn.c         | 16 ----------------
 net/bluetooth/hci_event.c        | 21 ++++-----------------
 3 files changed, 4 insertions(+), 34 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 8f8dd91737..34aa9d0290 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1480,7 +1480,6 @@ struct hci_conn *hci_conn_add_unset(struct hci_dev *hdev, int type,
 				    bdaddr_t *dst, u8 role);
 void hci_conn_del(struct hci_conn *conn);
 void hci_conn_hash_flush(struct hci_dev *hdev);
-void hci_conn_check_pending(struct hci_dev *hdev);
 
 struct hci_chan *hci_chan_create(struct hci_conn *conn);
 void hci_chan_del(struct hci_chan *chan);
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 816be7667a..a4beed8587 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2592,22 +2592,6 @@ void hci_conn_hash_flush(struct hci_dev *hdev)
 	}
 }
 
-/* Check pending connect attempts */
-void hci_conn_check_pending(struct hci_dev *hdev)
-{
-	struct hci_conn *conn;
-
-	BT_DBG("hdev %s", hdev->name);
-
-	hci_dev_lock(hdev);
-
-	conn = hci_conn_hash_lookup_state(hdev, ACL_LINK, BT_CONNECT2);
-	if (conn)
-		hci_acl_create_connection_sync(hdev, conn);
-
-	hci_dev_unlock(hdev);
-}
-
 static u32 get_link_mode(struct hci_conn *conn)
 {
 	u32 link_mode = 0;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 271c007928..e7887bae33 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -118,8 +118,6 @@ static u8 hci_cc_inquiry_cancel(struct hci_dev *hdev, void *data,
 		hci_discovery_set_state(hdev, DISCOVERY_STOPPED);
 	hci_dev_unlock(hdev);
 
-	hci_conn_check_pending(hdev);
-
 	return rp->status;
 }
 
@@ -150,8 +148,6 @@ static u8 hci_cc_exit_periodic_inq(struct hci_dev *hdev, void *data,
 
 	hci_dev_clear_flag(hdev, HCI_PERIODIC_INQ);
 
-	hci_conn_check_pending(hdev);
-
 	return rp->status;
 }
 
@@ -2312,10 +2308,8 @@ static void hci_cs_inquiry(struct hci_dev *hdev, __u8 status)
 {
 	bt_dev_dbg(hdev, "status 0x%2.2x", status);
 
-	if (status) {
-		hci_conn_check_pending(hdev);
+	if (status)
 		return;
-	}
 
 	if (hci_sent_cmd_data(hdev, HCI_OP_INQUIRY))
 		set_bit(HCI_INQUIRY, &hdev->flags);
@@ -2340,12 +2334,9 @@ static void hci_cs_create_conn(struct hci_dev *hdev, __u8 status)
 
 	if (status) {
 		if (conn && conn->state == BT_CONNECT) {
-			if (status != HCI_ERROR_COMMAND_DISALLOWED || conn->attempt > 2) {
-				conn->state = BT_CLOSED;
-				hci_connect_cfm(conn, status);
-				hci_conn_del(conn);
-			} else
-				conn->state = BT_CONNECT2;
+			conn->state = BT_CLOSED;
+			hci_connect_cfm(conn, status);
+			hci_conn_del(conn);
 		}
 	} else {
 		if (!conn) {
@@ -3035,8 +3026,6 @@ static void hci_inquiry_complete_evt(struct hci_dev *hdev, void *data,
 
 	bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);
 
-	hci_conn_check_pending(hdev);
-
 	if (!test_and_clear_bit(HCI_INQUIRY, &hdev->flags))
 		return;
 
@@ -3258,8 +3247,6 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 
 unlock:
 	hci_dev_unlock(hdev);
-
-	hci_conn_check_pending(hdev);
 }
 
 static void hci_reject_conn(struct hci_dev *hdev, bdaddr_t *bdaddr)
-- 
2.43.0

Re: [PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[Luiz Augusto von Dentz]

Hi Jonas,

On Tue, Feb 6, 2024 at 6:08 AM Jonas Dreßler <verdre@v0yd.nl> wrote:
>
> Since commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
> requests"), the kernel supports trying to connect again in case the
> bluetooth card is busy and fails to connect.
>
> The logic that should handle this became a bit spotty over time, and also
> cards these days appear to fail with more errors than just "Command
> Disallowed".
>
> This series refactores the handling of concurrent connection requests
> by serializing all "Create Connection" commands for ACL connections
> similar to how we do it for LE connections.
>
> ---
>
> v1: https://lore.kernel.org/linux-bluetooth/20240102185933.64179-1-verdre@v0yd.nl/
> v2: https://lore.kernel.org/linux-bluetooth/20240108183938.468426-1-verdre@v0yd.nl/
> v3: https://lore.kernel.org/linux-bluetooth/20240108224614.56900-1-verdre@v0yd.nl/
> v4:
>   - Removed first two commits since they are already applied
>   - Removed a BT_DBG() message in the acl_create_connection() function
>     while moving to hci_sync because it seemed out of place in hci_sync
>   - Added a mention of the test failure in mgmt-tester to commit message
>
> Jonas Dreßler (2):
>   Bluetooth: hci_conn: Only do ACL connections sequentially
>   Bluetooth: Remove pending ACL connection attempts
>
>  include/net/bluetooth/hci.h      |  1 +
>  include/net/bluetooth/hci_core.h |  1 -
>  include/net/bluetooth/hci_sync.h |  3 ++
>  net/bluetooth/hci_conn.c         | 83 +++-----------------------------
>  net/bluetooth/hci_event.c        | 21 ++------
>  net/bluetooth/hci_sync.c         | 70 +++++++++++++++++++++++++++
>  6 files changed, 86 insertions(+), 93 deletions(-)
>
> --
> 2.43.0


Doesn't seem to work with the new test:

Sequential connect - setup complete
Sequential connect - run
  Create connection finished
  Connect failed for Pair Device
  Create connection finished
Sequential connect - test timed out
Sequential connect - teardown

-- 
Luiz Augusto von Dentz

Re: [PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[Jonas Dreßler]

Hi Luiz,

On 06.02.24 23:22, Luiz Augusto von Dentz wrote:
> Hi Jonas,
> 
> On Tue, Feb 6, 2024 at 6:08 AM Jonas Dreßler <verdre@v0yd.nl> wrote:
>>
>> Since commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
>> requests"), the kernel supports trying to connect again in case the
>> bluetooth card is busy and fails to connect.
>>
>> The logic that should handle this became a bit spotty over time, and also
>> cards these days appear to fail with more errors than just "Command
>> Disallowed".
>>
>> This series refactores the handling of concurrent connection requests
>> by serializing all "Create Connection" commands for ACL connections
>> similar to how we do it for LE connections.
>>
>> ---
>>
>> v1: https://lore.kernel.org/linux-bluetooth/20240102185933.64179-1-verdre@v0yd.nl/
>> v2: https://lore.kernel.org/linux-bluetooth/20240108183938.468426-1-verdre@v0yd.nl/
>> v3: https://lore.kernel.org/linux-bluetooth/20240108224614.56900-1-verdre@v0yd.nl/
>> v4:
>>    - Removed first two commits since they are already applied
>>    - Removed a BT_DBG() message in the acl_create_connection() function
>>      while moving to hci_sync because it seemed out of place in hci_sync
>>    - Added a mention of the test failure in mgmt-tester to commit message
>>
>> Jonas Dreßler (2):
>>    Bluetooth: hci_conn: Only do ACL connections sequentially
>>    Bluetooth: Remove pending ACL connection attempts
>>
>>   include/net/bluetooth/hci.h      |  1 +
>>   include/net/bluetooth/hci_core.h |  1 -
>>   include/net/bluetooth/hci_sync.h |  3 ++
>>   net/bluetooth/hci_conn.c         | 83 +++-----------------------------
>>   net/bluetooth/hci_event.c        | 21 ++------
>>   net/bluetooth/hci_sync.c         | 70 +++++++++++++++++++++++++++
>>   6 files changed, 86 insertions(+), 93 deletions(-)
>>
>> --
>> 2.43.0
> 
> 
> Doesn't seem to work with the new test:
> 
> Sequential connect - setup complete
> Sequential connect - run
>    Create connection finished
>    Connect failed for Pair Device
>    Create connection finished
> Sequential connect - test timed out
> Sequential connect - teardown
> 

Oh you're right, it's because of the increased delay to 5.12 seconds for
sending the page timeout. We're actually waiting for connections to fail,
so the test will now take at least 5.12s * 3 instead of 2s * 3, which means
test timeout needs to be increased from 7 to more like 16 seconds.

Sorry for not catching this one, should've run the test before submitting
the patch...

Cheers,
Jonas

Re: [PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[patchwork-bot+bluetooth]

Hello:

This series was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Tue,  6 Feb 2024 12:08:12 +0100 you wrote:
> Since commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
> requests"), the kernel supports trying to connect again in case the
> bluetooth card is busy and fails to connect.
> 
> The logic that should handle this became a bit spotty over time, and also
> cards these days appear to fail with more errors than just "Command
> Disallowed".
> 
> [...]

Here is the summary with links:
  - [v4,1/2] Bluetooth: hci_conn: Only do ACL connections sequentially
    https://git.kernel.org/bluetooth/bluetooth-next/c/456561ba8e49
  - [v4,2/2] Bluetooth: Remove pending ACL connection attempts
    https://git.kernel.org/bluetooth/bluetooth-next/c/8e14d581d125

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v4 0/2] Bluetooth: Improve retrying of connection attempts

[Luiz Augusto von Dentz]

Hi Jonas,

On Wed, Feb 7, 2024 at 11:10 AM <patchwork-bot+bluetooth@kernel.org> wrote:
>
> Hello:
>
> This series was applied to bluetooth/bluetooth-next.git (master)
> by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:
>
> On Tue,  6 Feb 2024 12:08:12 +0100 you wrote:
> > Since commit 4c67bc74f016 ("[Bluetooth] Support concurrent connect
> > requests"), the kernel supports trying to connect again in case the
> > bluetooth card is busy and fails to connect.
> >
> > The logic that should handle this became a bit spotty over time, and also
> > cards these days appear to fail with more errors than just "Command
> > Disallowed".
> >
> > [...]
>
> Here is the summary with links:
>   - [v4,1/2] Bluetooth: hci_conn: Only do ACL connections sequentially
>     https://git.kernel.org/bluetooth/bluetooth-next/c/456561ba8e49
>   - [v4,2/2] Bluetooth: Remove pending ACL connection attempts
>     https://git.kernel.org/bluetooth/bluetooth-next/c/8e14d581d125
>
> You are awesome, thank you!
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Something is not quite right with these changes:

L2CAP BR/EDR Client - Timeout - test passed
L2CAP BR/EDR Client - Timeout - teardown
Bluetooth: hci0: command 0x0408 tx timeout
  Index Removed callback
    Index: 0x0000
L2CAP BR/EDR Client - Timeout - teardown complete
L2CAP BR/EDR Client - Timeout - done
L2CAP BR/EDR Client - Timeout                        Passed      22.329 seconds

The test seems to be blocked on teardown then the command times out,
0x0408 is HCI_OP_CREATE_CONN_CANCEL so I wonder why it would be timing
out. Anyway the test uses SO_SNDTIMEO to set a timeout at the socket
level but it doesn't seem it is used while creating the connection so
it probably needs to be passed down or something.


-- 
Luiz Augusto von Dentz