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Date:   Thu, 12 Nov 2020 19:31:39 -0800
From:   Richard Cochran <richardcochran@gmail.com>
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     Christian Eggers <ceggers@arri.de>,
        Jakub Kicinski <kuba@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        "David S . Miller" <davem@davemloft.net>,
        Kurt Kanzenbach <kurt.kanzenbach@linutronix.de>,
        George McCollister <george.mccollister@gmail.com>,
        Marek Vasut <marex@denx.de>,
        Helmut Grohne <helmut.grohne@intenta.de>,
        Paul Barker <pbarker@konsulko.com>,
        Codrin Ciubotariu <codrin.ciubotariu@microchip.com>,
        Tristram Ha <Tristram.Ha@microchip.com>,
        Woojung Huh <woojung.huh@microchip.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
        netdev@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v2 09/11] net: dsa: microchip: ksz9477: add
 hardware time stamping support
Message-ID: <20201113033139.GC32138@hoboy.vegasvil.org>
References: <20201112153537.22383-1-ceggers@arri.de>
 <20201112153537.22383-10-ceggers@arri.de>
 <20201113024020.ixzrpjxjfwme3wur@skbuf>
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On Fri, Nov 13, 2020 at 04:40:20AM +0200, Vladimir Oltean wrote:
> > @@ -103,6 +108,10 @@ static int ksz9477_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
> >  	if (ret)
> >  		goto error_return;
> >
> > +	spin_lock_irqsave(&dev->ptp_clock_lock, flags);
> 
> I believe that spin_lock_irqsave is unnecessary, since there is no code
> that runs in hardirq context.

The .adjtime method is in a system call context.  If all of the code
that manipulates dev->ptp_clock_time can sleep, then you can use a
mutex.  Otherwise spin_lock_irqsave is the safe choice.

Thanks,
Richard