On Thu, 2023-02-23 at 10:41 -0500, Alan Stern wrote: > On Thu, Feb 23, 2023 at 02:24:51PM +0100, Bastien Nocera wrote: > > Allow device specific drivers to change the wireless status of a > > device. > > This will allow user-space to know whether the device is available, > > whether or not specific USB interfaces can detect it. > > > > This can be used by wireless headsets with USB receivers to > > propagate to > > user-space whether or not the headset is turned on, so as to > > consider it > > as unavailable, and not switch to it just because the receiver is > > plugged in. > > > > Signed-off-by: Bastien Nocera <hadess@xxxxxxxxxx> > > --- > > drivers/usb/core/message.c | 13 +++++++++++++ > > drivers/usb/core/usb.c | 24 ++++++++++++++++++++++++ > > include/linux/usb.h | 4 ++++ > > 3 files changed, 41 insertions(+) > > > > diff --git a/drivers/usb/core/message.c > > b/drivers/usb/core/message.c > > index 127fac1af676..d5c7749d515e 100644 > > --- a/drivers/usb/core/message.c > > +++ b/drivers/usb/core/message.c > > @@ -1908,6 +1908,18 @@ static void __usb_queue_reset_device(struct > > work_struct *ws) > > usb_put_intf(iface); /* Undo _get_ in > > usb_queue_reset_device() */ > > } > > > > +/* > > + * Internal function to set the wireless_status sysfs attribute > > + * See usb_set_wireless_status() for more details > > + */ > > +static void __usb_wireless_status_intf(struct work_struct *ws) > > +{ > > + struct usb_interface *iface = > > + container_of(ws, struct usb_interface, > > wireless_status_work); > > + > > + usb_update_wireless_status_attr(iface); > > + usb_put_intf(iface); /* Undo _get_ in > > usb_set_wireless_status() */ > > +} > > Have you thought about what will happen if this routine ends up > running > after the interface has been deleted? I believe that usb_release_interface() will only be called once the last reference to the interface is dropped, so bar any refcounting bugs, the interface should always exist when this function is called. > > /* > > * usb_set_configuration - Makes a particular device setting be > > current > > @@ -2100,6 +2112,7 @@ int usb_set_configuration(struct usb_device > > *dev, int configuration) > > intf->dev.type = &usb_if_device_type; > > intf->dev.groups = usb_interface_groups; > > INIT_WORK(&intf->reset_ws, > > __usb_queue_reset_device); > > + INIT_WORK(&intf->wireless_status_work, > > __usb_wireless_status_intf); > > intf->minor = -1; > > device_initialize(&intf->dev); > > pm_runtime_no_callbacks(&intf->dev); > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index 11b15d7b357a..5f42c5b9d209 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -871,6 +871,30 @@ int usb_get_current_frame_number(struct > > usb_device *dev) > > } > > EXPORT_SYMBOL_GPL(usb_get_current_frame_number); > > > > +/** > > + * usb_set_wireless_status - sets the wireless_status struct > > member > > + * @dev: the device to modify > > + * @status: the new wireless status > > + * > > + * Set the wireless_status struct member to the new value, and > > emit > > + * sysfs changes as necessary. > > + * > > + * Returns: 0 on success, -EALREADY if already set. > > + */ > > +int usb_set_wireless_status(struct usb_interface *iface, > > + enum usb_wireless_status status) > > +{ > > + if (iface->wireless_status == status) > > + return -EALREADY; > > + > > + usb_get_intf(iface); > > + iface->wireless_status = status; > > + schedule_work(&iface->wireless_status_work); > > + > > + return 0; > > +} > > +EXPORT_SYMBOL_GPL(usb_set_wireless_status); > > This routine belongs in message.c, next to > __usb_wireless_status_intf(). Sure, done locally.