Messages in this thread | | | Subject | Re: [PATCH 4/4] Bluetooth: hci_ldisc: make sure we don't loose HCI_UART_TX_WAKEUP events | From | Marcel Holtmann <> | Date | Tue, 30 Aug 2016 09:53:53 -0700 |
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Hi Boris,
> 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; > +
I know this is correct, but I would actually make it visually different.
if (test_bit(UART_TX_WAKEUP, ..) { /* comment goes here */ if (!test_and_set_bit(UART_SENDING, ..) goto restart; }
For me with a proper comment that is a lot easier to read and grok that it is correct.
Regards
Marcel
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