diff options
| author | Johan Hedberg <johan.hedberg@intel.com> | 2015-03-28 12:17:36 +0300 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2015-03-28 22:05:11 +0300 |
| commit | 600b21507eb64bcd85bb87d06c2c2c451b565f02 (patch) | |
| tree | 74e5e9ab26ecd95f15ad855c3026800b424e6889 /net/bluetooth | |
| parent | 6331c686e664909988ecc35b040e1e96c137f5e0 (diff) | |
| download | linux-600b21507eb64bcd85bb87d06c2c2c451b565f02.tar.xz | |
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 <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net/bluetooth')
| -rw-r--r-- | net/bluetooth/hci_event.c | 20 |
1 files changed, 10 insertions, 10 deletions
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) |