Messages in this thread | | | Date | Mon, 3 Feb 2020 16:23:29 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH v3 04/12] mm: introduce page_ref_sub_return() |
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On Fri, Jan 31, 2020 at 07:40:21PM -0800, John Hubbard wrote: > An upcoming patch requires subtracting a large chunk of refcounts from > a page, and checking what the resulting refcount is. This is a little > different than the usual "check for zero refcount" that many of the > page ref functions already do. However, it is similar to a few other > routines that (like this one) are generally useful for things such as > 1-based refcounting. > > Add page_ref_sub_return(), that subtracts a chunk of refcounts > atomically, and returns an atomic snapshot of the result. > > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- > include/linux/page_ref.h | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h > index 14d14beb1f7f..b9cbe553d1e7 100644 > --- a/include/linux/page_ref.h > +++ b/include/linux/page_ref.h > @@ -102,6 +102,16 @@ static inline void page_ref_sub(struct page *page, int nr) > __page_ref_mod(page, -nr); > } > > +static inline int page_ref_sub_return(struct page *page, int nr) > +{ > + int ret = atomic_sub_return(nr, &page->_refcount); > + > + if (page_ref_tracepoint_active(__tracepoint_page_ref_mod)) > + __page_ref_mod(page, -nr);
Shouldn't it be __page_ref_mod_and_return() and relevant tracepoint?
> + > + return ret; > +} > + > static inline void page_ref_inc(struct page *page) > { > atomic_inc(&page->_refcount); > -- > 2.25.0 >
-- Kirill A. Shutemov
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