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Date:   Mon, 24 Jul 2023 19:12:04 +0800
Mime-Version: 1.0
Message-ID: <20230724111206.3067352-1-howardchung@google.com>
Subject: [PATCH v1] Bluetooth: Add timeout in disconnect when power off
From:   Howard Chung <howardchung@google.com>
To:     linux-bluetooth@vger.kernel.org, marcel@holtmann.org
Cc:     Howard Chung <howardchung@google.com>,
        Archie Pusaka <apusaka@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

For some controllers, it is known that when the HCI disconnect and HCI
Reset are too close to each other, the LMP disconnect command might not
been sent out yet and the command will be dropped by the controoler when
it is asked to reset itself. This could happen on powering off adapter.

One possible issue is that if a connection exists, and then powering off
and on adapter within a short time, then our host stack assumes the
conntection was disconnected but this might not be true, so if we issue
a connection to the peer, it will fail with ACL Already Connected error.

This CL makes the host stack to wait for |HCI_EV_DISCONN_COMPLETE| when
powering off with a configurable timeout unless the timeout is set to 0.

Reviewed-by: Archie Pusaka <apusaka@google.com>
Signed-off-by: Howard Chung <howardchung@google.com>
---
Hi upstream maintainers, this is tested with an AX211 device and Logi
K580 keyboard by the following procedures:
1. pair the peer and stay connected.
2. power off and on immediately
3. observe that the btsnoop log is consistent with the configured
   timeout.

 include/net/bluetooth/hci_core.h |  1 +
 net/bluetooth/hci_core.c         |  2 +-
 net/bluetooth/hci_sync.c         | 38 +++++++++++++++++++++++---------
 net/bluetooth/mgmt_config.c      |  6 +++++
 4 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 8200a6689b39..ce44f9c60059 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -432,6 +432,7 @@ struct hci_dev {
 	__u16		advmon_allowlist_duration;
 	__u16		advmon_no_filter_duration;
 	__u8		enable_advmon_interleave_scan;
+	__u16		discon_on_poweroff_timeout;
 
 	__u16		devid_source;
 	__u16		devid_vendor;
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 0fefa6788911..769865494f45 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2479,7 +2479,7 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
 	hdev->adv_instance_cnt = 0;
 	hdev->cur_adv_instance = 0x00;
 	hdev->adv_instance_timeout = 0;
-
+	hdev->discon_on_poweroff_timeout = 0;	/* Default to no timeout */
 	hdev->advmon_allowlist_duration = 300;
 	hdev->advmon_no_filter_duration = 500;
 	hdev->enable_advmon_interleave_scan = 0x00;	/* Default to disable */
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 3348a1b0e3f7..260e9f05359c 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5250,6 +5250,8 @@ static int hci_disconnect_sync(struct hci_dev *hdev, struct hci_conn *conn,
 			       u8 reason)
 {
 	struct hci_cp_disconnect cp;
+	unsigned long timeout;
+	int err;
 
 	if (conn->type == AMP_LINK)
 		return hci_disconnect_phy_link_sync(hdev, conn->handle, reason);
@@ -5258,19 +5260,33 @@ static int hci_disconnect_sync(struct hci_dev *hdev, struct hci_conn *conn,
 	cp.handle = cpu_to_le16(conn->handle);
 	cp.reason = reason;
 
-	/* Wait for HCI_EV_DISCONN_COMPLETE, not HCI_EV_CMD_STATUS, when the
-	 * reason is anything but HCI_ERROR_REMOTE_POWER_OFF. This reason is
-	 * used when suspending or powering off, where we don't want to wait
-	 * for the peer's response.
+	/* The HCI_ERROR_REMOTE_POWER_OFF is used when suspending or powering off,
+	 * so we don't want to waste time waiting for the reply of the peer.
+	 * However, if the configuration specified, we'll wait some time to give the
+	 * controller chance to actually send the disconnect command.
 	 */
-	if (reason != HCI_ERROR_REMOTE_POWER_OFF)
-		return __hci_cmd_sync_status_sk(hdev, HCI_OP_DISCONNECT,
-						sizeof(cp), &cp,
-						HCI_EV_DISCONN_COMPLETE,
-						HCI_CMD_TIMEOUT, NULL);
+	if (reason == HCI_ERROR_REMOTE_POWER_OFF && !hdev->discon_on_poweroff_timeout) {
+		return __hci_cmd_sync_status(hdev, HCI_OP_DISCONNECT,
+					     sizeof(cp), &cp, HCI_CMD_TIMEOUT);
+	}
 
-	return __hci_cmd_sync_status(hdev, HCI_OP_DISCONNECT, sizeof(cp), &cp,
-				     HCI_CMD_TIMEOUT);
+	if (reason == HCI_ERROR_REMOTE_POWER_OFF)
+		timeout = msecs_to_jiffies(hdev->discon_on_poweroff_timeout);
+	else
+		timeout = HCI_CMD_TIMEOUT;
+
+	err = __hci_cmd_sync_status_sk(hdev, HCI_OP_DISCONNECT,
+				       sizeof(cp), &cp,
+				       HCI_EV_DISCONN_COMPLETE,
+				       timeout, NULL);
+
+	/* Ignore the error in suspending or powering off case to avoid the procedure being
+	 * aborted.
+	 */
+	if (reason == HCI_ERROR_REMOTE_POWER_OFF)
+		return 0;
+
+	return err;
 }
 
 static int hci_le_connect_cancel_sync(struct hci_dev *hdev,
diff --git a/net/bluetooth/mgmt_config.c b/net/bluetooth/mgmt_config.c
index 6ef701c27da4..f3194e3642d9 100644
--- a/net/bluetooth/mgmt_config.c
+++ b/net/bluetooth/mgmt_config.c
@@ -78,6 +78,7 @@ int read_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
 		HDEV_PARAM_U16(advmon_allowlist_duration);
 		HDEV_PARAM_U16(advmon_no_filter_duration);
 		HDEV_PARAM_U8(enable_advmon_interleave_scan);
+		HDEV_PARAM_U16(discon_on_poweroff_timeout);
 	} __packed rp = {
 		TLV_SET_U16(0x0000, def_page_scan_type),
 		TLV_SET_U16(0x0001, def_page_scan_int),
@@ -111,6 +112,7 @@ int read_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
 		TLV_SET_U16(0x001d, advmon_allowlist_duration),
 		TLV_SET_U16(0x001e, advmon_no_filter_duration),
 		TLV_SET_U8(0x001f, enable_advmon_interleave_scan),
+		TLV_SET_U16(0x0020, discon_on_poweroff_timeout),
 	};
 
 	bt_dev_dbg(hdev, "sock %p", sk);
@@ -186,6 +188,7 @@ int set_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
 		case 0x001b:
 		case 0x001d:
 		case 0x001e:
+		case 0x0020:
 			exp_type_len = sizeof(u16);
 			break;
 		case 0x001f:
@@ -314,6 +317,9 @@ int set_def_system_config(struct sock *sk, struct hci_dev *hdev, void *data,
 		case 0x0001f:
 			hdev->enable_advmon_interleave_scan = TLV_GET_U8(buffer);
 			break;
+		case 0x00020:
+			hdev->discon_on_poweroff_timeout = TLV_GET_LE16(buffer);
+			break;
 		default:
 			bt_dev_warn(hdev, "unsupported parameter %u", type);
 			break;
-- 
2.41.0.487.g6d72f3e995-goog