linux-kernel - Re: [PATCH] usb: fotg210-hcd: Fix an error message

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Date:   Sat, 8 May 2021 09:26:09 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
CC:     <gregkh@...uxfoundation.org>, <shubhankarvk@...il.com>,
        <lee.jones@...aro.org>, <gustavoars@...nel.org>,
        <vulab@...as.ac.cn>, <john453@...aday-tech.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] usb: fotg210-hcd: Fix an error message

On Fri, 2021-05-07 at 09:06 +0200, Christophe JAILLET wrote:
> Le 07/05/2021 à 04:20, Chunfeng Yun a écrit :
> > On Thu, 2021-05-06 at 22:39 +0200, Christophe JAILLET wrote:
> >> 'retval' is known to be -ENODEV here.
> >> This is a hard-coded default error code which is not useful in the error
> >> message. Moreover, another error message is printed at the end of the
> >> error handling path. The corresponding error code (-ENOMEM) is more
> >> informative.
> >>
> >> So remove simplify the first error message.
> >>
> >> While at it, also remove the useless initialization of 'retval'.
> >>
> >> Fixes: 7d50195f6c50 ("usb: host: Faraday fotg210-hcd driver")
> >> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> >> ---
> >>   drivers/usb/host/fotg210-hcd.c | 4 ++--
> >>   1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/usb/host/fotg210-hcd.c b/drivers/usb/host/fotg210-hcd.c
> >> index 6cac642520fc..9c2eda0918e1 100644
> >> --- a/drivers/usb/host/fotg210-hcd.c
> >> +++ b/drivers/usb/host/fotg210-hcd.c
> >> @@ -5568,7 +5568,7 @@ static int fotg210_hcd_probe(struct platform_device *pdev)
> >>   	struct usb_hcd *hcd;
> >>   	struct resource *res;
> >>   	int irq;
> >> -	int retval = -ENODEV;
> >> +	int retval;
> >>   	struct fotg210_hcd *fotg210;
> >>   
> >>   	if (usb_disabled())
> >> @@ -5588,7 +5588,7 @@ static int fotg210_hcd_probe(struct platform_device *pdev)
> >>   	hcd = usb_create_hcd(&fotg210_fotg210_hc_driver, dev,
> >>   			dev_name(dev));
> >>   	if (!hcd) {
> >> -		dev_err(dev, "failed to create hcd with err %d\n", retval);
> >> +		dev_err(dev, "failed to create hcd\n");
> >>   		retval = -ENOMEM;
> > How about moving this line before dev_err()? then could keep error log
> > unchanged.
> > 
> 
> Mostly a matter of taste.
> I don't think it add any useful information (this is not something 
> coming from a call chain or that can have different values, it is just a 
> hard-coded constant) and the line after we will already have:
> 	dev_err(dev, "init %s fail, %d\n", dev_name(dev), retval);
> where retval = -ENOMEM
> 
> So the -ENOMEM error code is already reported.
Yes

> 
> Moreover, having error code reported or not is already not consistent in 
> the function. For example "failed to enable PCLK\n" where 'retval' could 
> be reported as well.
> 
> 
> 
> BTW, is it useful to have 'dev_name(dev)' in a dev_err?
dev_err(dev, ...) itself will print it.

> 
> CJ
> 
> >>   		goto fail_create_hcd;
> >>   	}
> > 
>