From cb19774faa57c51efa189d8b8606aeabccebc53b Mon Sep 17 00:00:00 2001 From: Ibrahim Abdelkader Date: Tue, 11 Aug 2026 10:37:29 +0200 Subject: [PATCH] Bluetooth: hci_sync: Clear HCI_CMD_PENDING when dropping the last request A synchronous HCI command that never receives a response leaves HCI_CMD_PENDING set: hci_req_cmd_complete() is the only place that clears it, and it only runs when a response matching the last command sent arrives. hci_send_cmd_sync() populates hdev->req_skb only when the flag transitions from clear to set, while hci_dev_open_sync() and hci_dev_close_sync() drop req_skb without clearing the flag. After a timeout followed by either, the two disagree: the flag claims a request is outstanding while req_skb is NULL. Subsequent synchronous commands are then sent with no req_skb, so hci_event_packet() has nothing to match an arriving event against, and the caller times out even though the controller answered. Commands answered by Command Complete recover on their own, since hci_req_cmd_complete() clears the flag as a side effect. Drivers using __hci_cmd_sync_ev() with a custom event do not, because a vendor event never reaches that path. On a WCN3988 (hci_qca over UART) this makes a controller firmware hang unrecoverable: the driver injects a hardware error and re-runs qca_setup(), qca_read_soc_version() waits for HCI_EV_VENDOR, the reply arrives within 4 ms and is discarded, and every retry fails the same way. The adapter is left down until the driver is unbound and rebound, or power is removed. Clear the flag wherever the last request is dropped, restoring the invariant that req_skb is non-NULL exactly when HCI_CMD_PENDING is set. Verified on hardware by forcing a command timeout: without this change setup fails on every attempt, with it setup succeeds on the first. Fixes: 2615fd9a7c25 ("Bluetooth: hci_sync: Fix overwriting request callback") Cc: stable@vger.kernel.org Signed-off-by: Ibrahim Abdelkader Signed-off-by: Hans de Goede Signed-off-by: Luiz Augusto von Dentz --- net/bluetooth/hci_sync.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index b5897545d795..4d6ab5d39e94 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -5448,6 +5448,7 @@ int hci_dev_open_sync(struct hci_dev *hdev) if (hdev->req_skb) { kfree_skb(hdev->req_skb); hdev->req_skb = NULL; + hci_dev_clear_flag(hdev, HCI_CMD_PENDING); } clear_bit(HCI_RUNNING, &hdev->flags); @@ -5632,6 +5633,7 @@ int hci_dev_close_sync(struct hci_dev *hdev) if (hdev->req_skb) { kfree_skb(hdev->req_skb); hdev->req_skb = NULL; + hci_dev_clear_flag(hdev, HCI_CMD_PENDING); } clear_bit(HCI_RUNNING, &hdev->flags);