[PATCH 0/1] introduce page_ref_inc_return

[PATCH 0/1] introduce page_ref_inc_return

[Christian Borntraeger]

commit 0139aa7b7fa1 ("mm: rename _count, field of the struct page,
to _refcount") changed all accesses to page->_count to use wrappers.
There is already a page_ref_dec_return and we need for kvm/s390
code the function "page_ref_inc_return" as well.

FWIW, the code is under
https://git.kernel.org/cgit/linux/kernel/git/kvms390/linux.git/log/?h=next


Can I get an ack to carry this patch via the KVM/s390 tree (will
be merged into Paolos kvm tree soon)?

David Hildenbrand (1):
  mm/page_ref: introduce page_ref_inc_return

 include/linux/page_ref.h | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.5.5

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[PATCH 1/1] mm/page_ref: introduce page_ref_inc_return

[Christian Borntraeger]

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

Let's introduce that helper.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 include/linux/page_ref.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h
index 8b5e0a9..610e132 100644
--- a/include/linux/page_ref.h
+++ b/include/linux/page_ref.h
@@ -124,6 +124,15 @@ static inline int page_ref_sub_and_test(struct page *page, int nr)
 	return ret;
 }
 
+static inline int page_ref_inc_return(struct page *page)
+{
+	int ret = atomic_inc_return(&page->_refcount);
+
+	if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return))
+		__page_ref_mod_and_return(page, 1, ret);
+	return ret;
+}
+
 static inline int page_ref_dec_and_test(struct page *page)
 {
 	int ret = atomic_dec_and_test(&page->_refcount);
-- 
2.5.5

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Re: [PATCH 1/1] mm/page_ref: introduce page_ref_inc_return

[Andrew Morton]

On Mon, 20 Jun 2016 12:38:13 +0200 Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: David Hildenbrand <dahi@linux.vnet.ibm.com>
> 
> Let's introduce that helper.
> 
> ...
>
> +static inline int page_ref_inc_return(struct page *page)
> +{
> +	int ret = atomic_inc_return(&page->_refcount);
> +
> +	if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return))
> +		__page_ref_mod_and_return(page, 1, ret);
> +	return ret;
> +}

Acked-by: Andrew Morton <akpm@linux-foundation.org>

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