[BUG] usb: xhci: Two possible sleep-in-atomic-context bugs

[Jia-Ju Bai]

The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16.7 are:

[FUNC] schedule
drivers/base/power/runtime.c, 741: schedule in rpm_resume
drivers/base/power/runtime.c, 1322: rpm_resume in pm_runtime_forbid
drivers/usb/host/xhci-hub.c, 647: pm_runtime_forbid in xhci_enter_test_mode
drivers/usb/host/xhci-hub.c, 632: _raw_spin_lock_irqsave in 
xhci_enter_test_mode

[FUNC] schedule
drivers/base/power/runtime.c, 570: schedule in rpm_suspend
drivers/base/power/runtime.c, 434: rpm_suspend in rpm_idle
drivers/base/power/runtime.c, 1343: rpm_idle in pm_runtime_allow
drivers/usb/host/xhci-hub.c, 670: pm_runtime_allow in xhci_exit_test_mode
drivers/usb/host/xhci-hub.c, 1387: xhci_exit_test_mode in xhci_hub_control
drivers/usb/host/xhci-hub.c, 1038: _raw_spin_lock_irqsave in 
xhci_hub_control

These bugs are found by my static analysis tool (DSAC-2) and checked by my
code review.

I do not know how to correctly fix these bugs, so I just report them.


Best wishes,
Jia-Ju Bai