From: Marcel Holtmann <marcel@holtmann.org>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
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 09:53:53 -0700 [thread overview]
Message-ID: <23C61632-54CF-43DD-8F99-B18176DF6C07@holtmann.org> (raw)
In-Reply-To: <1471592327-14133-5-git-send-email-boris.brezillon@free-electrons.com>
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
next prev parent reply other threads:[~2016-08-30 16:54 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 [this message]
2016-08-30 17:10 ` Boris Brezillon
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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