Return-Path: MIME-Version: 1.0 In-Reply-To: References: <1393362104-12175-1-git-send-email-andre.guedes@openbossa.org> <1393362104-12175-9-git-send-email-andre.guedes@openbossa.org> From: Andre Guedes Date: Wed, 26 Feb 2014 16:34:19 -0300 Message-ID: Subject: Re: [PATCH 08/17] Bluetooth: Introduce LE auto connection infrastructure To: Marcel Holtmann Cc: "linux-bluetooth@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 List-ID: Hi Marcel, On Wed, Feb 26, 2014 at 3:31 AM, Marcel Holtmann wrot= e: > Hi Andre, > >> This patch introduces the LE auto connection infrastructure which >> will be used to implement the LE auto connection options. >> >> 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). Finally, >> we also call hci_update_background_scan() in hci_le_conn_failed() so >> the background scan is restarted in case the connection establishment >> fails. This way the background scanning keeps running until all pending >> LE connection are established. >> >> At this point, resolvable addresses are not support by this >> infrastructure. The proper support is added in upcoming patches. >> >> Signed-off-by: Andre Guedes >> --- >> include/net/bluetooth/hci_core.h | 2 + >> net/bluetooth/hci_conn.c | 5 +++ >> net/bluetooth/hci_core.c | 93 ++++++++++++++++++++++++++++++++++= +++++- >> net/bluetooth/hci_event.c | 38 ++++++++++++++++ >> 4 files changed, 136 insertions(+), 2 deletions(-) >> >> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hc= i_core.h >> index e08405d..617cf49 100644 >> --- a/include/net/bluetooth/hci_core.h >> +++ b/include/net/bluetooth/hci_core.h >> @@ -806,6 +806,8 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bdad= dr_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); >> + >> void hci_uuids_clear(struct hci_dev *hdev); >> >> void hci_link_keys_clear(struct hci_dev *hdev); >> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c >> index ccf4a4f..e79351c 100644 >> --- a/net/bluetooth/hci_conn.c >> +++ b/net/bluetooth/hci_conn.c >> @@ -527,6 +527,11 @@ void hci_le_conn_failed(struct hci_conn *conn, u8 s= tatus) >> hci_proto_connect_cfm(conn, status); >> >> hci_conn_del(conn); >> + >> + /* Since we may have temporarily stopped the background scanning i= n >> + * favor of connection establishment, we should restart it. >> + */ >> + hci_update_background_scan(hdev); >> } >> >> static void create_le_conn_complete(struct hci_dev *hdev, u8 status) >> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c >> index 142ecd8..d242217 100644 >> --- a/net/bluetooth/hci_core.c >> +++ b/net/bluetooth/hci_core.c >> @@ -3281,7 +3281,7 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bd= addr_t *addr, u8 addr_type) >> >> entry =3D hci_pend_le_conn_lookup(hdev, addr, addr_type); >> if (entry) >> - return; >> + goto done; >> >> entry =3D kzalloc(sizeof(*entry), GFP_KERNEL); >> if (!entry) { >> @@ -3295,6 +3295,9 @@ void hci_pend_le_conn_add(struct hci_dev *hdev, bd= addr_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 */ >> @@ -3304,12 +3307,15 @@ void hci_pend_le_conn_del(struct hci_dev *hdev, = bdaddr_t *addr, u8 addr_type) >> >> entry =3D 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 */ >> @@ -4946,3 +4952,86 @@ void hci_req_add_le_scan_disable(struct hci_reque= st *req) >> cp.enable =3D LE_SCAN_DISABLE; >> hci_req_add(req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(cp), &cp); >> } >> + >> +static void update_background_scan_complete(struct hci_dev *hdev, u8 st= atus) >> +{ >> + 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_l= e_conns >> + * list. If there are pending LE connection we start the background sca= nning, >> + * 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; >> + >> + hci_req_add_le_scan_disable(&req); >> + >> + BT_DBG("%s stopping background scanning", hdev->name); >> + } else { >> + u8 own_addr_type; >> + >> + /* If there is at least one pending LE connection, we shou= ld >> + * 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 scanni= ng >> + * since some controllers are not able to scan and connect= at >> + * the same time. >> + */ >> + conn =3D hci_conn_hash_lookup_state(hdev, LE_LINK, BT_CONN= ECT); >> + if (conn) >> + return; >> + >> + /* Use private address since remote doesn't need to identi= fy us. >> + * Strictly speaking, this is not required since no SCAN_R= EQ is >> + * sent in passive scanning. >> + */ >> + if (hci_update_random_address(&req, true, &own_addr_type)) >> + return; > > the comment above is confusing. Reason is simple. We might use a RPA if L= E Privacy has been enabled. The require_privacy =3D=3D true will fallback t= o URPA in case privacy is not enabled. If privacy is enabled, then no matte= r what require_privacy is set to, we will use a random address. > > It should say something along the lines of this: > > /* Set require_privacy to true to avoid identification from > * unknown peer devices. Since this is passive scanning, no > * SCAN_REQ using the local identity should be sent. Mandating > * privacy is just an extra precaution. > */ Ok, I'll fix this comment. BR, Andre