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| author | Dean Jenkins <Dean_Jenkins@mentor.com> | 2017-04-28 15:57:26 +0300 |
|---|---|---|
| committer | Marcel Holtmann <marcel@holtmann.org> | 2017-04-30 13:22:14 +0300 |
| commit | 2d6f1da168e1d62c47f7d50135ac4cbd8411dcb1 (patch) | |
| tree | 5c30f562bc90fd01a73e840e2b68697af92ca6e7 /drivers/bluetooth/hci_ldisc.c | |
| parent | 048e1bd3a27fbeb84ccdff52e165370c1339a193 (diff) | |
| download | linux-2d6f1da168e1d62c47f7d50135ac4cbd8411dcb1.tar.xz | |
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.c | 3 |
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; |