linux-kernel - [PATCH 5/5] Bluetooth: hci_event: Try reconnecting on more kinds of errors

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Date: Tue,  2 Jan 2024 19:59:32 +0100
From: Jonas Dreßler <verdre@...d.nl>
To: Marcel Holtmann <marcel@...tmann.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: Jonas Dreßler <verdre@...d.nl>,
	linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: [PATCH 5/5] Bluetooth: hci_event: Try reconnecting on more kinds of errors

While some hardware seems to return "HCI Command Disallowed" errors when
trying to connect to too many devices at once, other hardware (eg. the
BCM4378 found in M1 macbooks) returns "HCI Hardware Failure" in this case.

And the Marvell 88W8897 in various Microsoft Surface devices behaves
different again: Here the "HCI Create Connection" succeeds, but later
a "HCI Connection Complete" event with status "Rejected Limited Resources"
comes in.

Handle all these cases as expected by userspace and reuse the existing
BT_CONNECT2 logic to try "HCI Create Connection" again after the ongoing
connection attempts have been completed.

Signed-off-by: Jonas Dreßler <verdre@...d.nl>
---
 include/net/bluetooth/hci.h |  1 +
 net/bluetooth/hci_event.c   | 26 +++++++++++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index fef723afd..23890f53e 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -637,6 +637,7 @@ enum {
 
 /* ---- HCI Error Codes ---- */
 #define HCI_ERROR_UNKNOWN_CONN_ID	0x02
+#define HCI_ERROR_HARDWARE_FAILURE	0x03
 #define HCI_ERROR_AUTH_FAILURE		0x05
 #define HCI_ERROR_PIN_OR_KEY_MISSING	0x06
 #define HCI_ERROR_MEMORY_EXCEEDED	0x07
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 1376092c5..46b6d7e27 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -2323,13 +2323,14 @@ static void hci_cs_create_conn(struct hci_dev *hdev, __u8 status)
 
 	if (status) {
 		if (conn && conn->state == BT_CONNECT) {
-			/* If the request failed with "Command Disallowed", the
+			/* If the request failed with a certain status, the
 			 * card is either using all its available "slots" for
 			 * attempting new connections, or it's currently
 			 * doing an HCI Inquiry. In these cases we'll try to
 			 * do the "Create Connection" request again later.
 			 */
-			if (status == HCI_ERROR_COMMAND_DISALLOWED) {
+			if (status == HCI_ERROR_COMMAND_DISALLOWED ||
+			    status == HCI_ERROR_HARDWARE_FAILURE) {
 				conn->state = BT_CONNECT2;
 
 				if (!hci_conn_hash_lookup_state(hdev, ACL_LINK, BT_CONNECT) &&
@@ -3254,7 +3255,26 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, void *data,
 
 done:
 	if (status) {
-		hci_conn_failed(conn, status);
+		if (status == HCI_ERROR_REJ_LIMITED_RESOURCES) {
+			conn->state = BT_CONNECT2;
+
+			if (!hci_conn_hash_lookup_state(hdev, ACL_LINK, BT_CONNECT) &&
+			    !test_bit(HCI_INQUIRY, &hdev->flags)) {
+				bt_dev_err(hdev,
+					   "\"Connect Complete\" event with error "
+					   "(0x%2.2x) indicating to try again, but "
+					   "there's no concurrent \"Create "
+					   "Connection\" nor an ongoing inquiry",
+					   status);
+
+				hci_conn_failed(conn, status);
+			}
+
+			hci_dev_unlock(hdev);
+			return;
+		} else {
+			hci_conn_failed(conn, status);
+		}
 	} else if (ev->link_type == SCO_LINK) {
 		switch (conn->setting & SCO_AIRMODE_MASK) {
 		case SCO_AIRMODE_CVSD:
-- 
2.43.0