Hi,
On 11/22/21 11:50, Mathias Nyman wrote:
> Fix the circular lock dependency and unbalanced unlock of addess0_mutex
> introduced when fixing an address0_mutex enumeration retry race in commit
> ae6dc22d2d1 ("usb: hub: Fix usb enumeration issue due to address0 race")
>
> Make sure locking order between port_dev->status_lock and address0_mutex
> is correct, and that address0_mutex is not unlocked in hub_port_connect
> "done:" codepath which may be reached without locking address0_mutex
>
> Fixes: 6ae6dc22d2d1 ("usb: hub: Fix usb enumeration issue due to address0 race")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Oh, this is great, with this patch I can finally hot-plug my
thunderbolt dock (and thus a XHCI controller) without the XHCI
controller given a whole bunch of weird errors (and some USB
devices not working), which it does not when already connected at boot.
I also tried the hotplug thingy with the previous fix without
this locking fix and then I actually hit the deadlock and things
like lsusb would hang.
If we can get these 2 fixes together merged soon and also backported
to the stable series that would be great:
Acked-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Regards,
Hans
> ---
> drivers/usb/core/hub.c | 20 ++++++++++++--------
> 1 file changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 00c3506324e4..00070a8a6507 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -5188,6 +5188,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
> struct usb_port *port_dev = hub->ports[port1 - 1];
> struct usb_device *udev = port_dev->child;
> static int unreliable_port = -1;
> + bool retry_locked;
>
> /* Disconnect any existing devices under this port */
> if (udev) {
> @@ -5244,10 +5245,10 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
>
> status = 0;
>
> - mutex_lock(hcd->address0_mutex);
> -
> for (i = 0; i < PORT_INIT_TRIES; i++) {
> -
> + usb_lock_port(port_dev);
> + mutex_lock(hcd->address0_mutex);
> + retry_locked = true;
> /* reallocate for each attempt, since references
> * to the previous one can escape in various ways
> */
> @@ -5255,6 +5256,8 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
> if (!udev) {
> dev_err(&port_dev->dev,
> "couldn't allocate usb_device\n");
> + mutex_unlock(hcd->address0_mutex);
> + usb_unlock_port(port_dev);
> goto done;
> }
>
> @@ -5276,13 +5279,13 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
> }
>
> /* reset (non-USB 3.0 devices) and get descriptor */
> - usb_lock_port(port_dev);
> status = hub_port_init(hub, udev, port1, i);
> - usb_unlock_port(port_dev);
> if (status < 0)
> goto loop;
>
> mutex_unlock(hcd->address0_mutex);
> + usb_unlock_port(port_dev);
> + retry_locked = false;
>
> if (udev->quirks & USB_QUIRK_DELAY_INIT)
> msleep(2000);
> @@ -5372,11 +5375,14 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
>
> loop_disable:
> hub_port_disable(hub, port1, 1);
> - mutex_lock(hcd->address0_mutex);
> loop:
> usb_ep0_reinit(udev);
> release_devnum(udev);
> hub_free_dev(udev);
> + if (retry_locked) {
> + mutex_unlock(hcd->address0_mutex);
> + usb_unlock_port(port_dev);
> + }
> usb_put_dev(udev);
> if ((status == -ENOTCONN) || (status == -ENOTSUPP))
> break;
> @@ -5399,8 +5405,6 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
> }
>
> done:
> - mutex_unlock(hcd->address0_mutex);
> -
> hub_port_disable(hub, port1, 1);
> if (hcd->driver->relinquish_port && !hub->hdev->parent) {
> if (status != -ENOTCONN && status != -ENODEV)
>
