From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: "Gustavo F. Padovan" <gustavo@padovan.org>,
Johan Hedberg <johan.hedberg@gmail.com>,
linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
jason.abele@gmail.com
Subject: Re: [PATCH 4/4] Bluetooth: hci_ldisc: make sure we don't loose HCI_UART_TX_WAKEUP events
Date: Tue, 30 Aug 2016 19:10:08 +0200 [thread overview]
Message-ID: <20160830191008.7d9d3612@bbrezillon> (raw)
In-Reply-To: <23C61632-54CF-43DD-8F99-B18176DF6C07@holtmann.org>
On Tue, 30 Aug 2016 09:53:53 -0700
Marcel Holtmann <marcel@holtmann.org> wrote:
> 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.
Sure, I'll address that.
next prev parent reply other threads:[~2016-08-30 17:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 7:38 [PATCH 0/4] Bluetooth: hci_uart: various fixes Boris Brezillon
2016-08-19 7:38 ` [PATCH 1/4] Bluetooth: hci_ldisc: fix a race in the hdev closing path Boris Brezillon
2016-08-30 16:53 ` Marcel Holtmann
2016-08-30 17:08 ` Boris Brezillon
2016-08-19 7:38 ` [PATCH 2/4] Bluetooth: hci_h5: fix a race in the " Boris Brezillon
2016-08-30 16:54 ` Marcel Holtmann
2016-08-19 7:38 ` [PATCH 3/4] Bluetooth: hci_ldisc: don't release resources in hci_uart_init_work() Boris Brezillon
2016-08-19 7:38 ` [PATCH 4/4] Bluetooth: hci_ldisc: make sure we don't loose HCI_UART_TX_WAKEUP events Boris Brezillon
2016-08-30 16:53 ` Marcel Holtmann
2016-08-30 17:10 ` Boris Brezillon [this message]
2016-08-30 13:26 ` [PATCH 0/4] Bluetooth: hci_uart: various fixes Boris Brezillon
2016-08-30 16:48 ` Marcel Holtmann
2016-08-30 17:22 ` Boris Brezillon
2016-08-31 2:08 ` Marcel Holtmann
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