[PATCH v1 20/36] mips: mm: convert __flush_dcache_pages() to __flush_dcache_folio_pages()

[Lorenzo Stoakes]

On Thu, Aug 28, 2025 at 10:51:46PM +0200, David Hildenbrand wrote:
> On 28.08.25 18:57, Lorenzo Stoakes wrote:
> > On Thu, Aug 28, 2025 at 12:01:24AM +0200, David Hildenbrand wrote:
> > > Let's make it clearer that we are operating within a single folio by
> > > providing both the folio and the page.
> > >
> > > This implies that for flush_dcache_folio() we'll now avoid one more
> > > page->folio lookup, and that we can safely drop the "nth_page" usage.
> > >
> > > Cc: Thomas Bogendoerfer <tsbogend at alpha.franken.de>
> > > Signed-off-by: David Hildenbrand <david at redhat.com>
> > > ---
> > >   arch/mips/include/asm/cacheflush.h | 11 +++++++----
> > >   arch/mips/mm/cache.c               |  8 ++++----
> > >   2 files changed, 11 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/arch/mips/include/asm/cacheflush.h b/arch/mips/include/asm/cacheflush.h
> > > index 5d283ef89d90d..8d79bfc687d21 100644
> > > --- a/arch/mips/include/asm/cacheflush.h
> > > +++ b/arch/mips/include/asm/cacheflush.h
> > > @@ -50,13 +50,14 @@ extern void (*flush_cache_mm)(struct mm_struct *mm);
> > >   extern void (*flush_cache_range)(struct vm_area_struct *vma,
> > >   	unsigned long start, unsigned long end);
> > >   extern void (*flush_cache_page)(struct vm_area_struct *vma, unsigned long page, unsigned long pfn);
> > > -extern void __flush_dcache_pages(struct page *page, unsigned int nr);
> > > +extern void __flush_dcache_folio_pages(struct folio *folio, struct page *page, unsigned int nr);
> >
> > NIT: Be good to drop the extern.
>
> I think I'll leave the one in, though, someone should clean up all of them
> in one go.

This is how we always clean these up though, buuut to be fair that's in mm.

>
> Just imagine how the other functions would think about the new guy showing
> off here. :)

;)

>
> >
> > >
> > >   #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
> > >   static inline void flush_dcache_folio(struct folio *folio)
> > >   {
> > >   	if (cpu_has_dc_aliases)
> > > -		__flush_dcache_pages(&folio->page, folio_nr_pages(folio));
> > > +		__flush_dcache_folio_pages(folio, folio_page(folio, 0),
> > > +					   folio_nr_pages(folio));
> > >   	else if (!cpu_has_ic_fills_f_dc)
> > >   		folio_set_dcache_dirty(folio);
> > >   }
> > > @@ -64,10 +65,12 @@ static inline void flush_dcache_folio(struct folio *folio)
> > >
> > >   static inline void flush_dcache_page(struct page *page)
> > >   {
> > > +	struct folio *folio = page_folio(page);
> > > +
> > >   	if (cpu_has_dc_aliases)
> > > -		__flush_dcache_pages(page, 1);
> > > +		__flush_dcache_folio_pages(folio, page, folio_nr_pages(folio));
> >
> > Hmmm, shouldn't this be 1 not folio_nr_pages()? Seems that the original
> > implementation only flushed a single page even if contained within a larger
> > folio?
>
> Yes, reworked it 3 times and messed it up during the last rework. Thanks!

Woot I found an actual bug :P

Yeah it's fiddly so understandable. :)

>
> --
> Cheers
>
> David / dhildenb
>

Cheers, Lorenzo