2024-01-08 18:45:04

by Jonas Dreßler

[permalink] [raw]
Subject: Re: [PATCH v2 4/4] Bluetooth: Remove pending ACL connection attempts

On 1/8/24 19:39, Jonas Dreßler wrote:
> 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 actual connect
> should 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 2c30834c1..d7483958d 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -1330,7 +1330,6 @@ struct hci_conn *hci_conn_add(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 541d55301..22033057b 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -2534,22 +2534,6 @@ 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_cmd_sync_queue(hdev, hci_acl_create_connection_sync, conn, NULL);
> -
> - 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 e8b4a0126..91973d6d1 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -117,8 +117,6 @@ 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;
> }
>
> @@ -149,8 +147,6 @@ 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;
> }
>
> @@ -2296,10 +2292,8 @@ 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;
> - }
>
> set_bit(HCI_INQUIRY, &hdev->flags);
> }
> @@ -2323,12 +2317,9 @@ 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) {
> @@ -3020,8 +3011,6 @@ 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;
>
> @@ -3247,8 +3236,6 @@ 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)

Please take a special look at this one: I'm not sure if I'm breaking the
functionality of deferred connecting using BT_CONNECT2 in
hci_conn_request_evt() here, as I don't see anywhere where we check for
this state and establish a connection later.

It seems that this is how hci_conn_request_evt() was initially written
though, hci_conn_check_pending() only got introduced later and seems
unrelated.

Thanks,
Jonas


2024-01-08 18:55:48

by Jonas Dreßler

[permalink] [raw]
Subject: Re: [PATCH v2 4/4] Bluetooth: Remove pending ACL connection attempts

On 1/8/24 19:44, Jonas Dreßler wrote:
> On 1/8/24 19:39, Jonas Dreßler wrote:
>> 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 actual connect
>> should 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 2c30834c1..d7483958d 100644
>> --- a/include/net/bluetooth/hci_core.h
>> +++ b/include/net/bluetooth/hci_core.h
>> @@ -1330,7 +1330,6 @@ struct hci_conn *hci_conn_add(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 541d55301..22033057b 100644
>> --- a/net/bluetooth/hci_conn.c
>> +++ b/net/bluetooth/hci_conn.c
>> @@ -2534,22 +2534,6 @@ 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_cmd_sync_queue(hdev, hci_acl_create_connection_sync,
>> conn, NULL);
>> -
>> -    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 e8b4a0126..91973d6d1 100644
>> --- a/net/bluetooth/hci_event.c
>> +++ b/net/bluetooth/hci_event.c
>> @@ -117,8 +117,6 @@ 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;
>>   }
>> @@ -149,8 +147,6 @@ 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;
>>   }
>> @@ -2296,10 +2292,8 @@ 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;
>> -    }
>>       set_bit(HCI_INQUIRY, &hdev->flags);
>>   }
>> @@ -2323,12 +2317,9 @@ 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) {
>> @@ -3020,8 +3011,6 @@ 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;
>> @@ -3247,8 +3236,6 @@ 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)
>
> Please take a special look at this one: I'm not sure if I'm breaking the
> functionality of deferred connecting using BT_CONNECT2 in
> hci_conn_request_evt() here, as I don't see anywhere where we check for
> this state and establish a connection later.
>
> It seems that this is how hci_conn_request_evt() was initially written
> though, hci_conn_check_pending() only got introduced later and seems
> unrelated.

Ahh nevermind... The check for BT_CONNECT2 on "Conn Complete event" got
introduced with 4c67bc74f01 ([Bluetooth] Support concurrent connect
requests). And later the deferred connection setup on "Conn Request
event" got introduced with 20714bfef8 ("Bluetooth: Implement deferred
sco socket setup").

I assume the latter commit was relying on the "Create Connection"
request "Conn Complete event" that got introduced with the former commit
then? That would imply that we use BT_CONNECT2 if there's already a
"Create Connection" going on when the "Conn Request event" happens, and
we must wait for that existing request to finish.. Is that how those
deferred connections are supposed to work?

>
> Thanks,
> Jonas