Re: [PATCH net 1/2] net: fec_ptp: add clock rate zero check

From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"peppe.cavallaro@st.com" <peppe.cavallaro@st.com>,
	"alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>,
	"joabreu@synopsys.com" <joabreu@synopsys.com>,
	"mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-stm32@st-md-mailman.stormreply.com" 
	<linux-stm32@st-md-mailman.stormreply.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [PATCH net 1/2] net: fec_ptp: add clock rate zero check
Date: Wed, 16 Jun 2021 14:28:59 +0100	[thread overview]
Message-ID: <20210616132859.GE22278@shell.armlinux.org.uk> (raw)
In-Reply-To: <VI1PR04MB68004D29895652864B4C1D20E60F9@VI1PR04MB6800.eurprd04.prod.outlook.com>

Hi Joakim,

On Wed, Jun 16, 2021 at 11:40:29AM +0000, Joakim Zhang wrote:
> Do you mean that print an error message then return directly? It seems better.

Nearly - one has to ensure that the cleanup functions don't provoke a
crash though. I notice fec_ptp_stop() makes use of fep->time_keep
and also fep->ptp_clock.

fep->time_keep is initialised after where you need to test for zero
cycle_speed, so the initialisation would need moving earlier.

I would have thought that ftp->ptp_clock should be NULL, so that's
probably okay, but should be checked that this assumption is in fact
true.

> if (!fep->cycle_speed) {
> 	dev_err(&fep->pdev->dev, "PTP clock rate should not be zero!\n");

I'd still say something like "PTP clock rate should not be zero,
disabling PTP" - say what's wrong and what we are doing. Also,
please avoid exclaimation marks in error messages.

Thanks.

-- 
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