[Intel-gfx] [PATCH i-g-t v2] i915/pm_rps: install SIGTERM handler for load_helper process

[Liu, Chuansheng]

Thanks for reviewing the patch, please see below comments.

> > So here we install the proper handler for signal SIGTERM in the
> > similar way. Without this patch, the GT may keep busy after
> > running this subtest. Enabling rps should be tracked on the
> > other side.
> >
> > Signed-off-by: Chuansheng Liu <chuansheng.liu at intel.com>
> > ---
> >  tests/i915/i915_pm_rps.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/tests/i915/i915_pm_rps.c b/tests/i915/i915_pm_rps.c
> > index ef627c0b..8c71c1a1 100644
> > --- a/tests/i915/i915_pm_rps.c
> > +++ b/tests/i915/i915_pm_rps.c
> > @@ -252,6 +252,7 @@ static void load_helper_run(enum load load)
> >
> >                 signal(SIGUSR1, load_helper_signal_handler);
> >                 signal(SIGUSR2, load_helper_signal_handler);
> > +               signal(SIGTERM, load_helper_signal_handler);
> 
> I don't see any behaviour changes to igt to cause it to send SIGTERM on
> exit_subtest.

Yes, exit_subtest() will not send SIGTERM out. But when main process calls
igt_exit() to exit, it hits the below assertion, then goes to fatal_sig_handler() with SIGABORT.
(i915_pm_rps:1680) igt_core-CRITICAL: Exiting with status code 98
i915_pm_rps: ../lib/igt_core.c:1775: igt_exit: Assertion `waitpid(-1, &tmp, WNOHANG) == -1 && errno == ECHILD' failed.
Received signal SIGABRT.

In fatal_sig_handler(), the installed exit handler fork_helper_exit_handler()
will send out the SIGTERM to all children process.

> 
> But you might as well just s/SIGUSR2/SIGTERM/ for clearer and common
> intentions.
Don't get your real point, SIGUSR1 is for actively stopping load_helper, SIGUSR2 is for
switching high and low load, the SIGTERM is for passively exiting.