linux-kernel - Re: [PATCH v10 12/15] platform/x86: dell-smbios: Add filtering support

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Message-ID: <20180129164424.yzem3xz3kt7qfxuf@pali>
Date:   Mon, 29 Jan 2018 17:44:24 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Mario.Limonciello@...l.com
Cc:     dvhart@...radead.org, andy.shevchenko@...il.com,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        luto@...nel.org, quasisec@...gle.com, rjw@...ysocki.net,
        mjg59@...gle.com, hch@....de, greg@...ah.com,
        gnomes@...rguk.ukuu.org.uk
Subject: Re: [PATCH v10 12/15] platform/x86: dell-smbios: Add filtering
 support

On Monday 29 January 2018 16:22:07 Mario.Limonciello@...l.com wrote:
> > -----Original Message-----
> > From: Pali Rohár [mailto:pali.rohar@...il.com]
> > Sent: Saturday, January 27, 2018 8:51 AM
> > To: Limonciello, Mario <Mario_Limonciello@...l.com>
> > Cc: dvhart@...radead.org; andy.shevchenko@...il.com; linux-
> > kernel@...r.kernel.org; platform-driver-x86@...r.kernel.org; luto@...nel.org;
> > quasisec@...gle.com; rjw@...ysocki.net; mjg59@...gle.com; hch@....de;
> > greg@...ah.com; gnomes@...rguk.ukuu.org.uk
> > Subject: Re: [PATCH v10 12/15] platform/x86: dell-smbios: Add filtering support
> > 
> > On Friday 05 January 2018 14:48:39 Mario.Limonciello@...l.com wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: platform-driver-x86-owner@...r.kernel.org [mailto:platform-driver-x86-
> > > > owner@...r.kernel.org] On Behalf Of Pali Rohár
> > > > Sent: Friday, January 5, 2018 8:44 AM
> > > > To: Limonciello, Mario <Mario_Limonciello@...l.com>
> > > > Cc: dvhart@...radead.org; andy.shevchenko@...il.com; linux-
> > > > kernel@...r.kernel.org; platform-driver-x86@...r.kernel.org;
> > luto@...nel.org;
> > > > quasisec@...gle.com; rjw@...ysocki.net; mjg59@...gle.com; hch@....de;
> > > > greg@...ah.com; gnomes@...rguk.ukuu.org.uk
> > > > Subject: Re: [PATCH v10 12/15] platform/x86: dell-smbios: Add filtering support
> > > >
> > > > On Friday 05 January 2018 14:32:54 Mario.Limonciello@...l.com wrote:
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: platform-driver-x86-owner@...r.kernel.org [mailto:platform-driver-
> > x86-
> > > > > > owner@...r.kernel.org] On Behalf Of Pali Rohár
> > > > > > Sent: Friday, January 5, 2018 5:13 AM
> > > > > > To: Limonciello, Mario <Mario_Limonciello@...l.com>
> > > > > > Cc: dvhart@...radead.org; Andy Shevchenko
> > <andy.shevchenko@...il.com>;
> > > > > > LKML <linux-kernel@...r.kernel.org>; platform-driver-
> > x86@...r.kernel.org;
> > > > Andy
> > > > > > Lutomirski <luto@...nel.org>; quasisec@...gle.com; rjw@...ysocki.net;
> > > > > > mjg59@...gle.com; hch@....de; Greg KH <greg@...ah.com>; Alan Cox
> > > > > > <gnomes@...rguk.ukuu.org.uk>
> > > > > > Subject: Re: [PATCH v10 12/15] platform/x86: dell-smbios: Add filtering
> > support
> > > > > >
> > > > > > I know that this patch is already applied and merged, but I spotted this
> > > > > > problem:
> > > > > >
> > > > > > On Thursday 19 October 2017 12:50:15 Mario Limonciello wrote:
> > > > > > > +/* calls that are explicitly blacklisted */
> > > > > > > +static struct smbios_call call_blacklist[] = {
> > > > > > > +	{0x0000, 01, 07}, /* manufacturing use */
> > > > > > > +	{0x0000, 06, 05}, /* manufacturing use */
> > > > > > > +	{0x0000, 11, 03}, /* write once */
> > > > > > > +	{0x0000, 11, 07}, /* write once */
> > > > > >
> > > > > > Numbers prefixed by zero means that they are in octal notation, right?
> > > > > Is that how the kernel interprets an integer prefix by zero?
> > > >
> > > > No, this is how C language define it. See e.g. C11 standard, section
> > > > 6.4.4.1 Integer constants:
> > > >
> > > > decimal-constant:
> > > > 	nonzero-digit
> > > > 	decimal-constant digit
> > > >
> > > > octal-constant:
> > > > 	0
> > > > 	octal-constant octal-digit
> > > >
> > > > So in C decimal number cannot start with digit zero.
> > > >
> > > > I think the place where octal numbers are used are in permissions (0777)
> > > >
> > > > > I prefixed by zero for readability, they're supposed to be decimal.
> > > > >
> > > > > > This can lead to misunderstanding, confusion or problems in future...
> > > > > >
> > > > > > Can we have all numbers either in hexadecimal or decimal notation?
> > > > >
> > > > > Could you elaborate more why this is problematic the way it is?
> > > >
> > > > Currently it is not problem as 7 is same number in octal (07) and
> > > > decimal (7). representation. But e.g. octal 077 is 63 in decimal.
> > > >
> > > > > Are you meaning you would rather see this?
> > > > > 	{0x0000, 1, 7}, /* manufacturing use */
> > > > > 	{0x0000, 6, 5}, /* manufacturing use */
> > > > > 	{0x0000, 11, 3}, /* write once */
> > > > > 	{0x0000, 11, 7}, /* write once */
> > > >
> > > > Yes, this is better. If you need to achieve alignment then use spaces.
> > > > Really, not leading zeros.
> > > >
> > > > > That seems less readable to me but should interpret the same way.
> > > >
> > > > Example:
> > > >
> > > > {0x000, 077, 7},
> > > > {0x000, 007, 7},
> > > >
> > > > is **not** same as
> > > >
> > > > {0x000,  77, 7},
> > > > {0x000,   7, 7},
> > > >
> > > > As first number in first section is (decimal) 63, not (decimal) 77.
> > > >
> > > > > Perhaps it would be better if you submit a patch with what is clearer to
> > > > > you.
> > > > >
> > > > > >
> > > > > > > +	{0x0000, 11, 11}, /* write once */
> > > > > > > +	{0x0000, 19, -1}, /* diagnostics */
> > > > > > > +	/* handled by kernel: dell-laptop */
> > > > > > > +	{0x0000, CLASS_INFO, SELECT_RFKILL},
> > > > > > > +	{0x0000, CLASS_KBD_BACKLIGHT, SELECT_KBD_BACKLIGHT},
> > > > > > > +};
> > > > > >
> > > > > > --
> > > > > > Pali Rohár
> > > > > > pali.rohar@...il.com
> > > >
> > > > --
> > > > Pali Rohár
> > > > pali.rohar@...il.com
> > >
> > > Thanks very much for sharing.  I wasn't aware of this.  I'll send a patch.
> > 
> > Hi! Do you have a patch for it?
> 
> I used the wrong tag so it didn't automatically CC you.  Sorry about that.
> It's here:
> 
> https://patchwork.kernel.org/patch/10146671/

Ok, looks good for me.

-- 
Pali Rohár
pali.rohar@...il.com

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