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From: "Huang, Ying" <ying.huang@intel.com>
To: Gregory Price <gregory.price@memverge.com>
Cc: Gregory Price <gourry.memverge@gmail.com>,  <linux-mm@kvack.org>,
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Subject: Re: [PATCH v5 03/11] mm/mempolicy: refactor sanitize_mpol_flags for
 reuse
In-Reply-To: <ZYq9klTts4yg8RhG@memverge.com> (Gregory Price's message of "Tue,
	26 Dec 2023 06:48:34 -0500")
References: <20231223181101.1954-1-gregory.price@memverge.com>
	<20231223181101.1954-4-gregory.price@memverge.com>
	<87y1dgdoou.fsf@yhuang6-desk2.ccr.corp.intel.com>
	<ZYp7P1fH8nvkr4o0@memverge.com> <ZYq9klTts4yg8RhG@memverge.com>
Date: Tue, 02 Jan 2024 17:09:55 +0800
Message-ID: <871qb0drto.fsf@yhuang6-desk2.ccr.corp.intel.com>
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Gregory Price <gregory.price@memverge.com> writes:

> On Tue, Dec 26, 2023 at 02:05:35AM -0500, Gregory Price wrote:
>> On Wed, Dec 27, 2023 at 04:39:29PM +0800, Huang, Ying wrote:
>> > Gregory Price <gourry.memverge@gmail.com> writes:
>> > 
>> > > +	unsigned short mode = (*mode_arg & ~MPOL_MODE_FLAGS);
>> > > +
>> > > +	*flags = *mode_arg & MPOL_MODE_FLAGS;
>> > > +	*mode_arg = mode;
>> > 
>> > It appears that it's unnecessary to introduce a local variable to split
>> > mode/flags.  Just reuse the original code?
>> > 
>
> Revisiting during fixes: Note the change from int to short.
>
> I chose to make this explicit because validate_mpol_flags takes a short.
>
> I'm fairly sure changing it back throws a truncation warning.

Why something like below doesn't work?

int sanitize_mpol_flags(int *mode, unsigned short *flags)
{
        *flags = *mode & MPOL_MODE_FLAGS;
        *mode &= ~MPOL_MODE_FLAGS;

        return validate_mpol_flags(*mode, flags);
}

--
Best Regards,
Huang, Ying