Hello,
My static analysis tool reports a possible deadlock in the ti driver in
Linux 5.16:
cpts_ptp_gettimeex()
mutex_lock(&cpts->ptp_clk_mutex); --> Line 260 (Lock A)
cpts_update_cur_time()
wait_for_completion_timeout(&cpts->ts_push_complete, HZ); --> Line
210 (Wait X)
cpts_overflow_check()
mutex_lock(&cpts->ptp_clk_mutex); --> Line 411 (Lock A)
cpts_update_cur_time()
cpts_fifo_read()
complete(&cpts->ts_push_complete); --> Line 142 (Wake X)
When cpts_ptp_gettimeex() is executed, "Wait X" is performed by holding
"Lock A". If cpts_overflow_check() is executed at this time, "Wake X"
cannot be performed to wake up "Wait X" in cpts_ptp_gettimeex(), because
"Lock A" has been already hold by cpts_ptp_gettimeex(), 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