linux-kernel - Re: [PATCH v3 25/27] powerpc/powernv/pmem: Expose the serial number in sysfs

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Date:   Fri, 28 Feb 2020 08:15:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Andrew Donnellan <ajd@...ux.ibm.com>
Cc:     Alastair D'Silva <alastair@....ibm.com>, alastair@...ilva.org,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kurz <groug@...d.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexey Kardashevskiy <aik@...abs.ru>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 25/27] powerpc/powernv/pmem: Expose the serial number
 in sysfs

On Fri, Feb 28, 2020 at 05:25:31PM +1100, Andrew Donnellan wrote:
> On 21/2/20 2:27 pm, Alastair D'Silva wrote:
> > +int ocxlpmem_sysfs_add(struct ocxlpmem *ocxlpmem)
> > +{
> > +	int i, rc;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(attrs); i++) {
> > +		rc = device_create_file(&ocxlpmem->dev, &attrs[i]);
> > +		if (rc) {
> > +			for (; --i >= 0;)
> > +				device_remove_file(&ocxlpmem->dev, &attrs[i]);
> 
> I'd rather avoid weird for loop constructs if possible.
> 
> Is it actually dangerous to call device_remove_file() on an attr that hasn't
> been added? If not then I'd rather define an err: label and loop over the
> whole array there.

None of this should be used at all, just use attribute groups properly
and the driver core will handle this all for you.

device_create/remove_file should never be called by anyone anymore if at all
possible.

thanks,

greg k-h