Possible race in ucb1400_ts.ko

[Anton Volkov]

Hello.

While searching for races in the Linux kernel I've come across 
"drivers/input/touchscreen/ucb1400_ts.ko" module. Here is a question 
that I came up with while analyzing results. Lines are given using the 
info from Linux v4.12.

Consider the following case:

Thread 1:                   Thread 2:
ucb1400_suspend
->ucb1400_ts_start
    ucb->stopped = false
    enable_irq()

ucb1400_resume
->ucb1400_ts_stop           ucb1400_irq
    ucb->stopped = true       while(!ucb->stopped && ...)
    (ucb1400_ts.c: line 230)  (ucb1400_ts.c: line 202)
    disable_irq()

The value of ucb->stopped may be changed in the midst of 'while' loop 
iterations or prevent all of them from happening. Is this feasible from 
your point of view? If so, is it a benign race or is it serious?

Thank you for your time.

-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@xxxxxxxxx