On Mon, Nov 21, 2016 at 11:47 AM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> On Sat, 19 Nov 2016 13:01:29 +0100,
> Andrej Krutak wrote:
>>
>> Deny userspace from using the interface concurrently.
>
> Could you clarify more what's wrong and what you're changing?
>
>
Userspace apps have to claim USB interfaces before using endpoints in
them (drivers/usb/core/devio.c:checkintf()). It's a lock mechanism so
that two "drivers"
don't steal data from each other. Kernel drivers don't necessarily
have to claim interfaces (obviously, because it worked so far) - but
they should, to lock out userspace...
Do you want that info in a v2 patch?
>>
>> Signed-off-by: Andrej Krutak <dev@xxxxxxxxx>
>> ---
>> sound/usb/line6/driver.h | 1 +
>> sound/usb/line6/podhd.c | 24 ++++++++++++++++++++++++
>> 2 files changed, 25 insertions(+)
>>
>> diff --git a/sound/usb/line6/driver.h b/sound/usb/line6/driver.h
>> index 7e3a3aa..5d18957 100644
>> --- a/sound/usb/line6/driver.h
>> +++ b/sound/usb/line6/driver.h
>> @@ -98,6 +98,7 @@ struct line6_properties {
>>
>> int altsetting;
>>
>> + unsigned ctrl_if;
>> unsigned ep_ctrl_r;
>> unsigned ep_ctrl_w;
>> unsigned ep_audio_r;
>> diff --git a/sound/usb/line6/podhd.c b/sound/usb/line6/podhd.c
>> index 49cd4a6..6c53b87 100644
>> --- a/sound/usb/line6/podhd.c
>> +++ b/sound/usb/line6/podhd.c
>> @@ -153,6 +153,7 @@ struct usb_line6_podhd {
>> .rats = &podhd_ratden},
>> .bytes_per_channel = 3 /* SNDRV_PCM_FMTBIT_S24_3LE */
>> };
>> +static struct usb_driver podhd_driver;
>>
>> static void podhd_startup_start_workqueue(unsigned long data);
>> static void podhd_startup_workqueue(struct work_struct *work);
>> @@ -291,8 +292,13 @@ static void podhd_disconnect(struct usb_line6 *line6)
>> struct usb_line6_podhd *pod = (struct usb_line6_podhd *)line6;
>>
>> if (pod->line6.properties->capabilities & LINE6_CAP_CONTROL) {
>> + struct usb_interface *intf;
>> +
>> del_timer_sync(&pod->startup_timer);
>> cancel_work_sync(&pod->startup_work);
>> +
>> + intf = usb_ifnum_to_if(line6->usbdev, pod->line6.properties->ctrl_if);
>> + usb_driver_release_interface(&podhd_driver, intf);
>> }
>> }
>>
>> @@ -304,10 +310,26 @@ static int podhd_init(struct usb_line6 *line6,
>> {
>> int err;
>> struct usb_line6_podhd *pod = (struct usb_line6_podhd *) line6;
>> + struct usb_interface *intf;
>>
>> line6->disconnect = podhd_disconnect;
>>
>> if (pod->line6.properties->capabilities & LINE6_CAP_CONTROL) {
>> + /* claim the data interface */
>> + intf = usb_ifnum_to_if(line6->usbdev, pod->line6.properties->ctrl_if);
>> + if (!intf) {
>> + dev_err(pod->line6.ifcdev, "interface %d not found\n",
>> + pod->line6.properties->ctrl_if);
>> + return -ENODEV;
>> + }
>> +
>> + err = usb_driver_claim_interface(&podhd_driver, intf, NULL);
>> + if (err != 0) {
>> + dev_err(pod->line6.ifcdev, "can't claim interface %d, error %d\n",
>> + pod->line6.properties->ctrl_if, err);
>> + return err;
>> + }
>> +
>> /* create sysfs entries: */
>> err = snd_card_add_dev_attr(line6->card, &podhd_dev_attr_group);
>> if (err < 0)
>> @@ -406,6 +428,7 @@ static int podhd_init(struct usb_line6 *line6,
>> .altsetting = 1,
>> .ep_ctrl_r = 0x81,
>> .ep_ctrl_w = 0x01,
>> + .ctrl_if = 1,
>> .ep_audio_r = 0x86,
>> .ep_audio_w = 0x02,
>> },
>> @@ -417,6 +440,7 @@ static int podhd_init(struct usb_line6 *line6,
>> .altsetting = 1,
>> .ep_ctrl_r = 0x81,
>> .ep_ctrl_w = 0x01,
>> + .ctrl_if = 1,
>> .ep_audio_r = 0x86,
>> .ep_audio_w = 0x02,
>> },
>> --
>> 1.9.1
>>
>>
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