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Bluetooth: hci_ldisc: Fix another race when closing the tty.

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The following race condition still existed:

         P1                                P2
  cancel_work_sync()
                                     hci_uart_tx_wakeup()
                                     hci_uart_write_work()
                                     hci_uart_dequeue()
  clear_bit(HCI_UART_PROTO_READY)
  hci_unregister_dev(hdev)
  hci_free_dev(hdev)
  hu->proto->close(hu)
  kfree(hu)
                                     access to hdev and hu

Cancelling the work after clearing the HCI_UART_PROTO_READY bit avoids
this as any hci_uart_tx_wakeup() issued after the flag is cleared will
detect that and not schedule further work.

Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Ronald Tschalär 2017-10-25 22:15:19 -07:00 committed by Marcel Holtmann
parent 459232fc0e
commit 0338b1b393
1 changed files with 2 additions and 2 deletions
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4
drivers/bluetooth/hci_ldisc.c
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@ -523,13 +523,13 @@ static void hci_uart_tty_close(struct tty_struct *tty)
if (hdev)
hci_uart_close(hdev);
cancel_work_sync(&hu->write_work);
if (test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
percpu_down_write(&hu->proto_lock);
clear_bit(HCI_UART_PROTO_READY, &hu->flags);
percpu_up_write(&hu->proto_lock);
cancel_work_sync(&hu->write_work);
if (hdev) {
if (test_bit(HCI_UART_REGISTERED, &hu->flags))
hci_unregister_dev(hdev);