[PATCH 5/6] mm/gup: Replace ACCESS_ONCE with READ_ONCE for STRICT_MM_TYPECHECKS

[PATCH 5/6] mm/gup: Replace ACCESS_ONCE with READ_ONCE for STRICT_MM_TYPECHECKS

[Michael Ellerman]

If STRICT_MM_TYPECHECKS is enabled the generic gup code fails to build
because we are using ACCESS_ONCE on non-scalar types.

Convert all uses to READ_ONCE.

Cc: akpm@linux-foundation.org
Cc: kirill.shutemov@linux.intel.com
Cc: aarcange@redhat.com
Cc: borntraeger@de.ibm.com
Cc: steve.capper@linaro.org
Cc: linux-mm@kvack.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 mm/gup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index a6e24e246f86..120c3adc843c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -901,7 +901,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
 		 *
 		 * for an example see gup_get_pte in arch/x86/mm/gup.c
 		 */
-		pte_t pte = ACCESS_ONCE(*ptep);
+		pte_t pte = READ_ONCE(*ptep);
 		struct page *page;
 
 		/*
@@ -1191,7 +1191,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	local_irq_save(flags);
 	pgdp = pgd_offset(mm, addr);
 	do {
-		pgd_t pgd = ACCESS_ONCE(*pgdp);
+		pgd_t pgd = READ_ONCE(*pgdp);
 
 		next = pgd_addr_end(addr, end);
 		if (pgd_none(pgd))
-- 
2.1.0

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Re: [PATCH 5/6] mm/gup: Replace ACCESS_ONCE with READ_ONCE for STRICT_MM_TYPECHECKS

[Christian Borntraeger]

Am 25.03.2015 um 10:11 schrieb Michael Ellerman:
> If STRICT_MM_TYPECHECKS is enabled the generic gup code fails to build
> because we are using ACCESS_ONCE on non-scalar types.
> 
> Convert all uses to READ_ONCE.

There is a similar patch from Jason Low in Andrews patch.
If that happens in 4.0-rc, we probably want to merge this before 4.0.


> 
> Cc: akpm@linux-foundation.org
> Cc: kirill.shutemov@linux.intel.com
> Cc: aarcange@redhat.com
> Cc: borntraeger@de.ibm.com
> Cc: steve.capper@linaro.org
> Cc: linux-mm@kvack.org
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
>  mm/gup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/gup.c b/mm/gup.c
> index a6e24e246f86..120c3adc843c 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -901,7 +901,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
>  		 *
>  		 * for an example see gup_get_pte in arch/x86/mm/gup.c
>  		 */
> -		pte_t pte = ACCESS_ONCE(*ptep);
> +		pte_t pte = READ_ONCE(*ptep);
>  		struct page *page;
> 
>  		/*
> @@ -1191,7 +1191,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  	local_irq_save(flags);
>  	pgdp = pgd_offset(mm, addr);
>  	do {
> -		pgd_t pgd = ACCESS_ONCE(*pgdp);
> +		pgd_t pgd = READ_ONCE(*pgdp);
> 
>  		next = pgd_addr_end(addr, end);
>  		if (pgd_none(pgd))
> 

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Re: [PATCH 5/6] mm/gup: Replace ACCESS_ONCE with READ_ONCE for STRICT_MM_TYPECHECKS

[Michael Ellerman]

On Wed, 2015-03-25 at 10:18 +0100, Christian Borntraeger wrote:
> Am 25.03.2015 um 10:11 schrieb Michael Ellerman:
> > If STRICT_MM_TYPECHECKS is enabled the generic gup code fails to build
> > because we are using ACCESS_ONCE on non-scalar types.
> > 
> > Convert all uses to READ_ONCE.
> 
> There is a similar patch from Jason Low in Andrews patch.

Ah sorry, I didn't think to check.

> If that happens in 4.0-rc, we probably want to merge this before 4.0.

My series can wait, it's not urgent. So I'll plan to merge mine once Andrew's
tree has gone into Linus' tree for 4.1.

cheers


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