Re: [PATCH 4/4] RISC-V: Fix non-smp kernel boot on SMP systems

[Atish Patra]

On 12/7/18 9:00 AM, Palmer Dabbelt wrote:
> On Mon, 03 Dec 2018 12:57:31 PST (-0800), atish.patra@xxxxxxx wrote:
> > Currently, clocksource registration happens for an invalid cpu
> > for non-smp kernels. This lead to kernel panic as cpu hotplug
> > registration will fail for those cpus.
> >
> > Do not proceed if hartid is invalid. Take this opprtunity to
> > print appropriate error strings for different failure cases.
> >
> > Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
> > ---
> >   drivers/clocksource/riscv_timer.c | 13 ++++++++++---
> >   1 file changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
> > index 39de6e49..4af4af47 100644
> > --- a/drivers/clocksource/riscv_timer.c
> > +++ b/drivers/clocksource/riscv_timer.c
> > @@ -108,6 +108,8 @@ static int __init riscv_timer_init_dt(struct device_node *n)
> >   	int cpuid, hartid, error;
> >
> >   	hartid = riscv_of_processor_hartid(n);
> > +	if (hartid < 0)
> > +		return hartid;
>
> This seems like it's just hiding a bug somewhere else.  We should at least put
> out a WARN here, as I'm not sure the error will propagate anywhere useful.
ok. I will add a warning here. That's what we are doing in plic as well.

Regards,
Atish
> >   	cpuid = riscv_hartid_to_cpuid(hartid);
> >
> >   	if (cpuid != smp_processor_id())
> > @@ -115,14 +117,19 @@ static int __init riscv_timer_init_dt(struct device_node *n)
> >
> >   	/* This should be called only for boot cpu */
> >   	riscv_timebase = riscv_timebase_frequency(n);
> > -	clocksource_register_hz(&riscv_clocksource, riscv_timebase);
> > +	error = clocksource_register_hz(&riscv_clocksource, riscv_timebase);
> >
> > +	if (error) {
> > +		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
> > +		       error, cpuid);
> > +		return error;
> > +	}
> >   	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
> >   			 "clockevents/riscv/timer:starting",
> >   			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
> >   	if (error)
> > -		pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
> > -		       error, cpuid);
> > +		pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
> > +		       error);
> >   	return error;
> >   }