linux-kernel - Re: [RFC PATCH v2 06/14] x86/hpet: Configure the timer used by the hardlockup detector

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Message-ID: <alpine.DEB.2.21.1903262211220.1789@nanos.tec.linutronix.de>
Date:   Tue, 26 Mar 2019 22:13:06 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
cc:     Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
        Ashok Raj <ashok.raj@...el.com>,
        Andi Kleen <andi.kleen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, Tony Luck <tony.luck@...el.com>,
        Clemens Ladisch <clemens@...isch.de>,
        Arnd Bergmann <arnd@...db.de>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [RFC PATCH v2 06/14] x86/hpet: Configure the timer used by the
 hardlockup detector

On Wed, 27 Feb 2019, Ricardo Neri wrote:
> +#ifdef CONFIG_X86_HARDLOCKUP_DETECTOR_HPET
> +struct hpet_hld_data *hpet_hardlockup_detector_assign_timer(void)
> +{
> +	struct hpet_hld_data *hdata;
> +	unsigned int cfg;
> +
> +	cfg = hpet_readl(HPET_Tn_CFG(HPET_WD_TIMER_NR));
> +
> +	if (!(cfg & HPET_TN_FSB_CAP))
> +		return NULL;
> +
> +	hdata = kzalloc(sizeof(*hdata), GFP_KERNEL);
> +	if (!hdata)
> +		return NULL;
> +
> +	hdata->flags = HPET_DEV_FSB_CAP;

Pointless.

> +
> +	if (cfg & HPET_TN_PERIODIC_CAP)
> +		hdata->flags |= HPET_DEV_PERI_CAP;

This can be expressed by a simple:

     hdata->has_periodic = 1;

And no flag shuffling required at all.

Thanks,

	tglx