From: Johan Hedberg <johan.hedberg@xxxxxxxxx>
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@xxxxxxxxx>
---
net/bluetooth/hci_event.c | 20 ++++++++++----------
1 file 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)
--
2.1.0
--
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