The above commit reordered spin_lock/unlock and now `&dev->lock' is acquired
(rather than released) before calling `dev->driver->disconnect',
`dev->driver->setup', `dev->driver->suspend', `usb_gadget_giveback_request', and
`usb_gadget_udc_reset'.
But this *may* not be the right way to fix the problem pointed by d3cb25a121.
Note that the other usb/gadget/udc drivers do release the lock before calling
these functions. There are also inconsistencies within pch_udc.c, where
`dev->driver->disconnect' is called while holding `&dev->lock' in lines 613 and
1184, but not in line 2739.
Finally, commit d3cb25a121 may have introduced several potential deadlocks.
For instance, EBA (https://github.com/models-team/eba) reports:
Double lock in drivers/usb/gadget/udc/pch_udc.c
first at 2791: spin_lock(& dev->lock); [pch_udc_isr]
second at 2694: spin_lock(& dev->lock); [pch_udc_svc_cfg_interrupt]
after calling from 2793: pch_udc_dev_isr(dev, dev_intr);
after calling from 2724: pch_udc_svc_cfg_interrupt(dev);
Similarly, other potential deadlocks are 2791 -> 2793 -> 2721 -> 2657; and
2791 -> 2793 -> 2711 -> 2573 -> 1499 -> 1480.
Fixes: d3cb25a121 ("usb: gadget: udc: fix spin_lock in pch_udc")
Signed-off-by: Iago Abal <mail@iagoabal.eu>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
1d23d16a88