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[1/4] mm: add is_highmem_addr() helper

Message ID 1459427384-21374-2-git-send-email-boris.brezillon@free-electrons.com (mailing list archive)
State New, archived
Headers show

Commit Message

Boris BREZILLON March 31, 2016, 12:29 p.m. UTC
Add an helper to check if a virtual address is in the highmem region.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
 include/linux/highmem.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Comments

Vignesh Raghavendra April 4, 2016, 8:14 a.m. UTC | #1
Hi,

On 03/31/2016 05:59 PM, Boris Brezillon wrote:
> Add an helper to check if a virtual address is in the highmem region.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
>  include/linux/highmem.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index bb3f329..13dff37 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -41,6 +41,14 @@ void kmap_flush_unused(void);
>  
>  struct page *kmap_to_page(void *addr);
>  
> +static inline bool is_highmem_addr(const void *x)
> +{
> +	unsigned long vaddr = (unsigned long)x;
> +
> +	return vaddr >=  PKMAP_BASE &&
> +	       vaddr < ((PKMAP_BASE + LAST_PKMAP) * PAGE_SIZE);


Shouldn't this be:
		vaddr < (PKMAP_BASE + (LAST_PKMAP * PAGE_SIZE)) ?
Boris BREZILLON April 4, 2016, 3:05 p.m. UTC | #2
On Mon, 4 Apr 2016 13:44:11 +0530
Vignesh R <vigneshr@ti.com> wrote:

> Hi,
> 
> On 03/31/2016 05:59 PM, Boris Brezillon wrote:
> > Add an helper to check if a virtual address is in the highmem region.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > ---
> >  include/linux/highmem.h | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> > index bb3f329..13dff37 100644
> > --- a/include/linux/highmem.h
> > +++ b/include/linux/highmem.h
> > @@ -41,6 +41,14 @@ void kmap_flush_unused(void);
> >  
> >  struct page *kmap_to_page(void *addr);
> >  
> > +static inline bool is_highmem_addr(const void *x)
> > +{
> > +	unsigned long vaddr = (unsigned long)x;
> > +
> > +	return vaddr >=  PKMAP_BASE &&
> > +	       vaddr < ((PKMAP_BASE + LAST_PKMAP) * PAGE_SIZE);
> 
> 
> Shouldn't this be:
> 		vaddr < (PKMAP_BASE + (LAST_PKMAP * PAGE_SIZE)) ?

Oops, yes indeed.

Anyway, given Russell's feedback I don't think I'm gonna follow up on
this series.

Sorry.

Boris
diff mbox

Patch

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index bb3f329..13dff37 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -41,6 +41,14 @@  void kmap_flush_unused(void);
 
 struct page *kmap_to_page(void *addr);
 
+static inline bool is_highmem_addr(const void *x)
+{
+	unsigned long vaddr = (unsigned long)x;
+
+	return vaddr >=  PKMAP_BASE &&
+	       vaddr < ((PKMAP_BASE + LAST_PKMAP) * PAGE_SIZE);
+}
+
 #else /* CONFIG_HIGHMEM */
 
 static inline unsigned int nr_free_highpages(void) { return 0; }
@@ -50,6 +58,11 @@  static inline struct page *kmap_to_page(void *addr)
 	return virt_to_page(addr);
 }
 
+static inline bool is_highmem_addr(const void *x)
+{
+	return false;
+}
+
 #define totalhigh_pages 0UL
 
 #ifndef ARCH_HAS_KMAP