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authorDean Jenkins <Dean_Jenkins@mentor.com>2017-04-28 13:57:26 +0100
committerMarcel Holtmann <marcel@holtmann.org>2017-04-30 12:22:14 +0200
commit2d6f1da168e1d62c47f7d50135ac4cbd8411dcb1 (patch)
tree5c30f562bc90fd01a73e840e2b68697af92ca6e7 /drivers/bluetooth/hci_ldisc.c
parent048e1bd3a27fbeb84ccdff52e165370c1339a193 (diff)
Bluetooth: hci_ldisc: Add protocol check to hci_uart_tx_wakeup()
Before attempting to schedule a work-item onto hu->write_work in hci_uart_tx_wakeup(), check that the Data Link protocol layer is still bound to the HCI UART driver. Failure to perform this protocol check causes a race condition between the work queue hu->write_work running hci_uart_write_work() and the Data Link protocol layer being unbound (closed) in hci_uart_tty_close(). Note hci_uart_tty_close() does have a "cancel_work_sync(&hu->write_work)" but it is ineffective because it cannot prevent work-items being added to hu->write_work after cancel_work_sync() has run. Therefore, add a check for HCI_UART_PROTO_READY into hci_uart_tx_wakeup() which prevents scheduling of the work queue when HCI_UART_PROTO_READY is in the clear state. However, note a small race condition remains because the hci_uart_tx_wakeup() thread can run in parallel with the hci_uart_tty_close() thread so it is possible that a schedule of hu->write_work can occur when HCI_UART_PROTO_READY is cleared. A complete solution needs locking of the threads which is implemented in a future commit. Signed-off-by: Dean Jenkins <Dean_Jenkins@mentor.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'drivers/bluetooth/hci_ldisc.c')
-rw-r--r--drivers/bluetooth/hci_ldisc.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 6f9e406b28a6..2edd30556956 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -125,6 +125,9 @@ static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
int hci_uart_tx_wakeup(struct hci_uart *hu)
{
+ if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
+ return 0;
+
if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) {
set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
return 0;