From: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To: Sonny Sasaka <sonnysasaka@chromium.org>
Cc: "linux-bluetooth@vger.kernel.org"
<linux-bluetooth@vger.kernel.org>,
Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Subject: Re: [PATCH BlueZ] Check whether device is connected before attaching EATT
Date: Thu, 10 Jun 2021 13:59:36 -0700 [thread overview]
Message-ID: <CABBYNZKG45JktXfxo=SkxrmykpKjTbDu34kz0NpaHhM0CqHTuQ@mail.gmail.com> (raw)
In-Reply-To: <20210610181756.430-1-sonnysasaka@chromium.org>
Hi Sonny,
On Thu, Jun 10, 2021 at 11:20 AM Sonny Sasaka <sonnysasaka@chromium.org> wrote:
>
> Due to a race condition, device_attach_att() may be reached when the
> dev is actually already disconnected but dev->att is not yet cleaned up
> by att_disconnect_cb(). Therefore we should check whether the dev is
> connected before attaching EATT.
>
> The race condition is discovered at rare cases when there is a very
> quick reconnection after disconnection so that device_attach_att() is
> called even before att_disconnect_cb(). This case is more probable to
> happen when the host goes to suspend right before dev_disconnected() is
> invoked and when the host is woken up by a reconnection the reconnection
> is processed earlier than the cleanup in att_disconnect_cb().
>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>
> ---
> src/device.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/device.c b/src/device.c
> index 65838f59f..319a929ee 100644
> --- a/src/device.c
> +++ b/src/device.c
> @@ -5306,7 +5306,7 @@ bool device_attach_att(struct btd_device *dev, GIOChannel *io)
> return false;
> }
>
> - if (dev->att) {
> + if (btd_device_is_connected(dev) && dev->att) {
> if (btd_opts.gatt_channels == bt_att_get_channels(dev->att)) {
> DBG("EATT channel limit reached");
> return false;
Perhaps we should have this check earlier, also there seems to be
something wrong with att_io then, if the device is no longer connected
att_io shall have been unrefed as well.
> --
> 2.31.0
>
--
Luiz Augusto von Dentz
prev parent reply other threads:[~2021-06-10 20:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 18:17 [PATCH BlueZ] Check whether device is connected before attaching EATT Sonny Sasaka
2021-06-10 19:01 ` [BlueZ] " bluez.test.bot
2021-06-10 20:59 ` Luiz Augusto von Dentz [this message]
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