Hello,
My static analysis tool reports a possible deadlock in the opt3001
driver in Linux 5.16:
opt3001_read_raw()
mutex_lock(&opt->lock); --> Line 399 (Lock A)
opt3001_get_lux()
wait_event_timeout(opt->result_ready_queue, ...) --> Line 276 (Wait X)
mutex_lock(&opt->lock); --> Line 412 (Unlock A)
opt3001_irq()
mutex_lock(&opt->lock); --> Line 693 (Lock A)
mutex_unlock(&opt->lock); --> Line 730 (Unlock A)
wake_up(&opt->result_ready_queue); --> Line 733 (Wake X)
When opt3001_read_raw() is executed, "Wait X" is performed by holding
"Lock A". If opt3001_irq() is executed at this time, "Wake X" cannot be
performed to wake up "Wait X" in opt3001_read_raw(), because "Lock A"
has been already hold by opt3001_read_raw(), 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 and how to fix
it if it is real.
Any feedback would be appreciated, thanks :)
Best wishes,
Jia-Ju Bai
