[BUG] usb: typec: ucsi: possible deadlock in ucsi_pr_swap() and ucsi_handle_connector_change()

[Jia-Ju Bai]

Hello,

My static analysis tool reports a possible deadlock in the ucsi driver 
in Linux 5.16:

ucsi_pr_swap()
  mutex_lock(&con->lock); --> Line 962 (Lock A)
  wait_for_completion_timeout(&con->complete, ...) --> Line 981 (Wait X)

ucsi_handle_connector_change()
  mutex_lock(&con->lock); --> Line 763 (Lock A)
  complete(&con->complete); --> Line 782 (Wake X)
  complete(&con->complete); --> Line 807 (Wake X)

When ucsi_pr_swap() is executed, "Wait X" is performed by holding "Lock 
A". If ucsi_handle_connector_change() is executed at this time, "Wake X" 
cannot be performed to wake up "Wait X" in 
ucsi_handle_connector_change(), because "Lock A" has been already held 
by ucsi_handle_connector_change(), causing a possible deadlock.
I find that "Wait X" is performed with a timeout, to relieve the 
possible deadlock; but I think this timeout can cause inefficient execution.

I am not quite sure whether this possible problem is real.
Any feedback would be appreciated, thanks :)


Best wishes,
Jia-Ju Bai