From 600b21507eb64bcd85bb87d06c2c2c451b565f02 Mon Sep 17 00:00:00 2001 From: Johan Hedberg Date: Sat, 28 Mar 2015 11:17:36 +0200 Subject: Bluetooth: Fix race condition with HCI_RESET flag During the HCI init phase a completed request might be the last part of the setup procedure after which the actual init procedure starts. The init procedure begins with a call to hci_reset_req() which sets the HCI_RESET flag. The purpose of this flag is to make us ignore any updates to ncmd/cmd_cnt as long as we haven't received the command complete event for the HCI_Reset. There's a potential race with this however: hci_req_cmd_complete(hdev, opcode, status); if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags)) { atomic_set(&hdev->cmd_cnt, 1); if (!skb_queue_empty(&hdev->cmd_q)) queue_work(hdev->workqueue, &hdev->cmd_work); } Since the hci_req_cmd_complete() will trigger the completion of the setup stage, it's possible that hci_reset_req() gets called before we try to read ev->ncmd and the HCI_RESET flag. Because of this the cmd_cnt would never be updated and the hci_reset_req() in practice ends up blocking itself. This patch fixes the issue by updating cmd_cnt before notifying the request completion, and then reading it again to determine whether the cmd_work should be queued or not. Signed-off-by: Johan Hedberg Signed-off-by: Marcel Holtmann --- net/bluetooth/hci_event.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'net/bluetooth/hci_event.c') diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 62f92a508961..3ac23964e108 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -3027,13 +3027,13 @@ static void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *skb) if (opcode != HCI_OP_NOP) cancel_delayed_work(&hdev->cmd_timer); + if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags)) + atomic_set(&hdev->cmd_cnt, 1); + hci_req_cmd_complete(hdev, opcode, status); - if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags)) { - atomic_set(&hdev->cmd_cnt, 1); - if (!skb_queue_empty(&hdev->cmd_q)) - queue_work(hdev->workqueue, &hdev->cmd_work); - } + if (atomic_read(&hdev->cmd_cnt) && !skb_queue_empty(&hdev->cmd_q)) + queue_work(hdev->workqueue, &hdev->cmd_work); } static void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb) @@ -3122,15 +3122,15 @@ static void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb) if (opcode != HCI_OP_NOP) cancel_delayed_work(&hdev->cmd_timer); + if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags)) + atomic_set(&hdev->cmd_cnt, 1); + if (ev->status || (hdev->sent_cmd && !bt_cb(hdev->sent_cmd)->req_event)) hci_req_cmd_complete(hdev, opcode, ev->status); - if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags)) { - atomic_set(&hdev->cmd_cnt, 1); - if (!skb_queue_empty(&hdev->cmd_q)) - queue_work(hdev->workqueue, &hdev->cmd_work); - } + if (atomic_read(&hdev->cmd_cnt) && !skb_queue_empty(&hdev->cmd_q)) + queue_work(hdev->workqueue, &hdev->cmd_work); } static void hci_hardware_error_evt(struct hci_dev *hdev, struct sk_buff *skb) -- cgit