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Subject[PATCH 4/4] Bluetooth: hci_ldisc: make sure we don't loose HCI_UART_TX_WAKEUP events
Date
The HCI_UART_TX_WAKEUP flag checking is racy and some HCI_UART_TX_WAKEUP
events can be lost.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
drivers/bluetooth/hci_ldisc.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 27f73294edcb..ee7b25f1c6ce 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -172,6 +172,17 @@ restart:
goto restart;

clear_bit(HCI_UART_SENDING, &hu->tx_state);
+
+ /*
+ * One last check to make sure hci_uart_tx_wakeup() did not set
+ * HCI_UART_TX_WAKEUP while we where clearing HCI_UART_SENDING.
+ * The work might have been scheduled by someone else in the
+ * meantime, in this case we return directly.
+ */
+ if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state) &&
+ !test_and_set_bit(HCI_UART_SENDING, &hu->tx_state))
+ goto restart;
+
}

static void hci_uart_init_work(struct work_struct *work)
--
2.7.4
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