[PATCH RFC v2 3/3] Bluetooth: Add hdev->recv_bt_vendor() to handle BT vendor frames

[Zijun Hu]

For unsolicited VSE and ACL frames with vendor reserved handles:
Many transport drivers pre-process them in the RX-path because the BT core
cannot recognize them, and cause:

- Impact performance since skb_clone() in IRQ-disabled context
- Difficult to debug as frames consumed without btmon logging

Fix by adding the hook to process them within stack's process
context, when they have been logged by btmon.

Signed-off-by: Zijun Hu <zijun.hu@xxxxxxxxxxxxxxxx>
---
 include/net/bluetooth/hci_core.h |  3 +++
 net/bluetooth/hci_core.c         | 33 +++++++++++++++++++++++++++++++++
 net/bluetooth/hci_event.c        |  5 +++++
 3 files changed, 41 insertions(+)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 428261591288..12f3720f6cc8 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -646,6 +646,8 @@ struct hci_dev {
 	int (*setup)(struct hci_dev *hdev);
 	int (*shutdown)(struct hci_dev *hdev);
 	int (*send)(struct hci_dev *hdev, struct sk_buff *skb);
+	/* Return true if @skb was consumed, false otherwise */
+	bool (*recv_bt_vendor)(struct hci_dev *hdev, struct sk_buff *skb);
 	void (*recv_vendor_pkt)(struct hci_dev *hdev, struct sk_buff *skb);
 	void (*notify)(struct hci_dev *hdev, unsigned int evt);
 	void (*hw_error)(struct hci_dev *hdev, u8 code);
@@ -2329,6 +2331,7 @@ static inline int hci_check_conn_params(u16 min, u16 max, u16 latency,
 int hci_register_cb(struct hci_cb *hcb);
 int hci_unregister_cb(struct hci_cb *hcb);
 
+bool hci_recv_bt_vendor(struct hci_dev *hdev, struct sk_buff *skb);
 int hci_send_vendor_frame(struct hci_dev *hdev, struct iov_iter *iter);
 
 int __hci_cmd_send(struct hci_dev *hdev, u16 opcode, u32 plen,
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 90807562e8ed..21ef748e3528 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3830,6 +3830,12 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 	__u16 handle, flags;
 	int err;
 
+	/* Header is valid when ACL frame arrives here */
+	if (hci_recv_bt_vendor(hdev, skb)) {
+		hdev->stat.acl_rx++;
+		return;
+	}
+
 	hdr = skb_pull_data(skb, sizeof(*hdr));
 	if (!hdr) {
 		bt_dev_err(hdev, "ACL packet too small");
@@ -3918,6 +3924,33 @@ static void hci_isodata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 			   handle, err);
 }
 
+bool hci_recv_bt_vendor(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_event_hdr *evt_hdr;
+	u8 evt, pkt_type;
+
+	if (!hdev->recv_bt_vendor)
+		return false;
+
+	pkt_type = hci_skb_pkt_type(skb);
+
+	/* Save the event code before calling into the driver, since @skb
+	 * may be freed once consumed.
+	 */
+	if (pkt_type == HCI_EVENT_PKT) {
+		evt_hdr = hci_event_hdr(skb);
+		evt = evt_hdr->evt;
+	}
+
+	if (!hdev->recv_bt_vendor(hdev, skb))
+		return false;
+
+	if (pkt_type == HCI_EVENT_PKT && evt != HCI_EV_VENDOR)
+		bt_dev_warn(hdev, "consumed unexpected BT event 0x%2.2x", evt);
+
+	return true;
+}
+
 static bool hci_req_is_complete(struct hci_dev *hdev)
 {
 	struct sk_buff *skb;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ea858391c789..94c02b66bdfa 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -7801,6 +7801,11 @@ void hci_event_packet(struct hci_dev *hdev, struct sk_buff *skb)
 		goto done;
 	}
 
+	if (hci_recv_bt_vendor(hdev, skb)) {
+		hdev->stat.evt_rx++;
+		return;
+	}
+
 	hci_dev_lock(hdev);
 	kfree_skb(hdev->recv_event);
 	hdev->recv_event = skb_clone(skb, GFP_KERNEL);

-- 
2.34.1