Re: [v3 PATCH 6/8] clocksource/drivers/riscv: Add required checks during clock source init

From: Christoph Hellwig <hch@infradead.org>
To: Atish Patra <atish.patra@wdc.com>
Cc: linux-riscv@lists.infradead.org, "Patrick Stählin" <me@packi.ch>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Damien Le Moal" <Damien.LeMoal@wdc.com>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Alan Kao" <alankao@andestech.com>,
	"Dmitriy Cherkasov" <dmitriy@oss-tech.org>,
	"Anup Patel" <anup@brainfault.org>,
	"Daniel Lezcano" <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org, "Zong Li" <zongbox@gmail.com>,
	"Palmer Dabbelt" <palmer@sifive.com>,
	"Paul Walmsley" <paul.walmsley@sifive.com>,
	"Andreas Schwab" <schwab@suse.de>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>
Subject: Re: [v3 PATCH 6/8] clocksource/drivers/riscv: Add required checks during clock source init
Date: Fri, 8 Feb 2019 01:04:05 -0800	[thread overview]
Message-ID: <20190208090405.GC16932@infradead.org> (raw)
In-Reply-To: <1549590681-24125-7-git-send-email-atish.patra@wdc.com>

On Thu, Feb 07, 2019 at 05:51:19PM -0800, Atish Patra 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. Moreover,
> riscv_hartid_to_cpuid can return errors now.
> 
> Do not proceed if hartid or cpuid is invalid. Take this opprtunity
> to print appropriate error strings for different failure cases.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  drivers/clocksource/timer-riscv.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index 43189220..3c7ea75b 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -95,13 +95,30 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>  	struct clocksource *cs;
>  
>  	hartid = riscv_of_processor_hartid(n);
> +	if (hartid < 0) {
> +		pr_warn("Not valid hartid for node [%pOF] error = [%d]\n",
> +			n, hartid);
> +		return hartid;
> +	}
> +
>  	cpuid = riscv_hartid_to_cpuid(hartid);
> +	if (cpuid < 0) {
> +		pr_warn("Invalid cpuid for hartid [%d]\n", hartid);
> +		return cpuid;
> +	}
>  
>  	if (cpuid != smp_processor_id())
>  		return 0;
>  
> +	pr_err("%s: Registering clocksource cpuid [%d] hartid [%d]\n",
> +	       __func__, cpuid, hartid);

This does not look like an error case to me.  At best it is info,
if not debug.