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Date: Tue, 13 Feb 2024 16:53:01 +0000
From: Mark Rutland <mark.rutland@arm.com>
To: Ryan Roberts <ryan.roberts@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
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	Andrew Morton <akpm@linux-foundation.org>,
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	David Hildenbrand <david@redhat.com>,
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	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 21/25] arm64/mm: Implement new
 [get_and_]clear_full_ptes() batch APIs
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In-Reply-To: <aaf2bc8e-3fe3-4d41-ab5b-fca99b33c8a4@arm.com>

On Tue, Feb 13, 2024 at 04:48:50PM +0000, Ryan Roberts wrote:
> On 13/02/2024 16:43, Mark Rutland wrote:
> > On Fri, Feb 02, 2024 at 08:07:52AM +0000, Ryan Roberts wrote:

> >> +static inline void __clear_full_ptes(struct mm_struct *mm, unsigned long addr,
> >> +				pte_t *ptep, unsigned int nr, int full)
> >> +{
> >> +	for (;;) {
> >> +		__ptep_get_and_clear(mm, addr, ptep);
> >> +		if (--nr == 0)
> >> +			break;
> >> +		ptep++;
> >> +		addr += PAGE_SIZE;
> >> +	}
> >> +}
> > 
> > The loop construct is a bit odd; can't this be:
> 
> I found it a little odd at first, but its avoiding the ptep and addr increments
> the last time through the loop. Its the preferred pattern for these functions in
> core-mm. See default set_ptes(), wrprotect_ptes(), clear_full_ptes() in
> include/linux/pgtable.h.
> 
> So I'd prefer to leave it as is so that we match them. What do you think?

That's fair enough; it I'm happy with it as-is.

Mark.