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Message-ID: <20220407141254.3kpg75l4byytwfye@skbuf>
Date: Thu, 7 Apr 2022 14:12:55 +0000
From: Vladimir Oltean <vladimir.oltean@....com>
To: Michael Walle <michael@...le.cc>
CC: Claudiu Manoil <claudiu.manoil@....com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>,
Florian Fainelli <f.fainelli@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
"UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: dsa: felix: suppress -EPROBE_DEFER errors
On Thu, Apr 07, 2022 at 04:04:20PM +0200, Michael Walle wrote:
> Am 2022-04-07 15:56, schrieb Vladimir Oltean:
> > On Thu, Apr 07, 2022 at 03:06:25PM +0200, Michael Walle wrote:
> > > Due to missing prerequisites the probe of the felix switch might be
> > > deferred:
> > > [ 4.435305] mscc_felix 0000:00:00.5: Failed to register DSA
> > > switch: -517
> > >
> > > It's not an error. Use dev_err_probe() to demote the error to a debug
> > > message. While at it, replace all the dev_err()'s in the probe with
> > > dev_err_probe().
> > >
> > > Signed-off-by: Michael Walle <michael@...le.cc>
> > > ---
> >
> > Please limit the dev_err_probe() to dsa_register_switch(). The resource
> > that is missing is the DSA master, see of_find_net_device_by_node().
> > The others cannot possibly return -EPROBE_DEFER.
>
> This was my rationale (from the function doc):
>
> * Note that it is deemed acceptable to use this function for error
> * prints during probe even if the @err is known to never be -EPROBE_DEFER.
> * The benefit compared to a normal dev_err() is the standardized format
> * of the error code and the fact that the error code is returned.
>
> In any case I don't have a strong opinion.
Take this case:
err = -ENOMEM;
- dev_err(&pdev->dev, "Failed to allocate driver memory\n");
+ dev_err_probe(&pdev->dev, err, "Failed to allocate driver memory\n");
(1) there is no need to print ENOMEM if we say "failed to allocate memory"
(2) we don't use the return value of dev_err_probe() anyway, we have
actual teardown to do (pci_disable_device).
(3) we _surely_ know that -ENOMEM != -EPROBE_DEFER
>
> > >
> > > Should this be a patch with a Fixes tag?
> >
> > Whichever way you wish, no preference.
>
> I'll limit it to just the one dev_err() and add a Fixes,
> there might be scripts out there who greps dmesg for errors.
Ok.
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