From: Salah Triki <salah.triki@gmail.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>,
Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
open list <linux-kernel@vger.kernel.org>,
Alan Stern <stern@rowland.harvard.edu>,
Oliver Neukum <oliver@neukum.org>
Subject: Re: [PATCH v2] bluetooth: bcm203x: update the reference count of udev
Date: Mon, 2 Aug 2021 20:34:11 +0100 [thread overview]
Message-ID: <20210802193411.GA1006176@pc> (raw)
In-Reply-To: <9B2209B6-D371-432B-A3F5-F1CD7C7967A3@holtmann.org>
On Sun, Aug 01, 2021 at 08:01:06PM +0200, Marcel Holtmann wrote:
> Hi Salah,
>
> > Use usb_get_dev() to increment the reference count of the usb device
> > structure in order to avoid releasing the structure while it is still in
> > use. And use usb_put_dev() to decrement the reference count and thus,
> > when it will be equal to 0 the structure will be released.
> >
> > Signed-off-by: Salah Triki <salah.triki@gmail.com>
> > ---
> > Change since v1:
> > Modification of the description
> >
> > drivers/bluetooth/bcm203x.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/bluetooth/bcm203x.c b/drivers/bluetooth/bcm203x.c
> > index e667933c3d70..547d35425d70 100644
> > --- a/drivers/bluetooth/bcm203x.c
> > +++ b/drivers/bluetooth/bcm203x.c
> > @@ -166,7 +166,7 @@ static int bcm203x_probe(struct usb_interface *intf, const struct usb_device_id
> > if (!data)
> > return -ENOMEM;
> >
> > - data->udev = udev;
> > + data->udev = usb_get_dev(udev);
> > data->state = BCM203X_LOAD_MINIDRV;
> >
> > data->urb = usb_alloc_urb(0, GFP_KERNEL);
> > @@ -244,6 +244,8 @@ static void bcm203x_disconnect(struct usb_interface *intf)
> >
> > usb_set_intfdata(intf, NULL);
> >
> > + usb_put_dev(data->udev);
> > +
> > usb_free_urb(data->urb);
> > kfree(data->fw_data);
> > kfree(data->buffer);
>
> I do not understand this. If this is something broken, then it is broken in
> btusb.c as well and that driver is heavily used by all sorts of devices. So
> we should have seen bug reports about this.
>
> Regards
>
> Marcel
>
Hi Marcel,
The patch is based on the following documentation of usb_get_dev():
[quote]
Each live reference to a device should be refcounted.
Drivers for USB interfaces should normally record such references in their
probe() methods, when they bind to an interface, and release them by calling
usb_put_dev(), in their disconnect() methods.
[/quote]
Regards
Salah
next prev parent reply other threads:[~2021-08-02 19:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-31 15:41 [PATCH v2] bluetooth: bcm203x: update the reference count of udev Salah Triki
2021-08-01 18:01 ` Marcel Holtmann
2021-08-02 19:34 ` Salah Triki [this message]
2021-08-02 20:16 ` Alan Stern
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