* [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire
@ 2015-08-02 15:11 Andrey Konovalov
2015-08-02 16:08 ` Peter Zijlstra
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Andrey Konovalov @ 2015-08-02 15:11 UTC (permalink / raw)
To: linux-arm-kernel
Replace ACCESS_ONCE() macro in smp_store_release() and smp_load_acquire()
with WRITE_ONCE() and READ_ONCE() on x86, arm, arm64, ia64, metag, mips,
powerpc, s390, sparc and asm-generic since ACCESS_ONCE does not work
reliably on non-scalar types.
WRITE_ONCE() and READ_ONCE() were introduced in the commits 230fa253df63
("kernel: Provide READ_ONCE and ASSIGN_ONCE") and 43239cbe79fc ("kernel:
Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)").
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
Changed in v2:
- Other archs besides x86.
arch/arm/include/asm/barrier.h | 4 ++--
arch/arm64/include/asm/barrier.h | 4 ++--
arch/ia64/include/asm/barrier.h | 4 ++--
arch/metag/include/asm/barrier.h | 4 ++--
arch/mips/include/asm/barrier.h | 4 ++--
arch/powerpc/include/asm/barrier.h | 4 ++--
arch/s390/include/asm/barrier.h | 4 ++--
arch/sparc/include/asm/barrier_64.h | 4 ++--
arch/x86/include/asm/barrier.h | 8 ++++----
include/asm-generic/barrier.h | 4 ++--
10 files changed, 22 insertions(+), 22 deletions(-)
diff --git a/arch/arm/include/asm/barrier.h b/arch/arm/include/asm/barrier.h
index 6c2327e..7039357 100644
--- a/arch/arm/include/asm/barrier.h
+++ b/arch/arm/include/asm/barrier.h
@@ -67,12 +67,12 @@
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 0fa47c4..ef93b20 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -44,12 +44,12 @@
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
index 843ba43..df896a1 100644
--- a/arch/ia64/include/asm/barrier.h
+++ b/arch/ia64/include/asm/barrier.h
@@ -66,12 +66,12 @@
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
diff --git a/arch/metag/include/asm/barrier.h b/arch/metag/include/asm/barrier.h
index 5a696e5..172b7e5 100644
--- a/arch/metag/include/asm/barrier.h
+++ b/arch/metag/include/asm/barrier.h
@@ -90,12 +90,12 @@ static inline void fence(void)
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h
index 7ecba84..752e0b8 100644
--- a/arch/mips/include/asm/barrier.h
+++ b/arch/mips/include/asm/barrier.h
@@ -133,12 +133,12 @@
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index 51ccc72..0eca6ef 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -76,12 +76,12 @@
do { \
compiletime_assert_atomic_type(*p); \
smp_lwsync(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_lwsync(); \
___p1; \
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index e6f8615..d48fe01 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -42,12 +42,12 @@
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
diff --git a/arch/sparc/include/asm/barrier_64.h b/arch/sparc/include/asm/barrier_64.h
index 809941e..14a9286 100644
--- a/arch/sparc/include/asm/barrier_64.h
+++ b/arch/sparc/include/asm/barrier_64.h
@@ -60,12 +60,12 @@ do { __asm__ __volatile__("ba,pt %%xcc, 1f\n\t" \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index e51a8f8..d2bcfbe 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -57,12 +57,12 @@
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
@@ -74,12 +74,12 @@ do { \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 55e3abc..b42afad 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -108,12 +108,12 @@
do { \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
- ACCESS_ONCE(*p) = (v); \
+ WRITE_ONCE(*p, v); \
} while (0)
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = ACCESS_ONCE(*p); \
+ typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
smp_mb(); \
___p1; \
--
2.5.0.rc2.392.g76e840b
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire
2015-08-02 15:11 [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire Andrey Konovalov
@ 2015-08-02 16:08 ` Peter Zijlstra
2015-08-02 20:50 ` Davidlohr Bueso
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Peter Zijlstra @ 2015-08-02 16:08 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, Aug 02, 2015 at 05:11:04PM +0200, Andrey Konovalov wrote:
> Replace ACCESS_ONCE() macro in smp_store_release() and smp_load_acquire()
> with WRITE_ONCE() and READ_ONCE() on x86, arm, arm64, ia64, metag, mips,
> powerpc, s390, sparc and asm-generic since ACCESS_ONCE does not work
> reliably on non-scalar types.
>
> WRITE_ONCE() and READ_ONCE() were introduced in the commits 230fa253df63
> ("kernel: Provide READ_ONCE and ASSIGN_ONCE") and 43239cbe79fc ("kernel:
> Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)").
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire
2015-08-02 15:11 [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire Andrey Konovalov
2015-08-02 16:08 ` Peter Zijlstra
@ 2015-08-02 20:50 ` Davidlohr Bueso
2015-08-03 1:41 ` Michael Ellerman
2015-08-03 6:02 ` Ralf Baechle
3 siblings, 0 replies; 5+ messages in thread
From: Davidlohr Bueso @ 2015-08-02 20:50 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, 2015-08-02 at 17:11 +0200, Andrey Konovalov wrote:
> Replace ACCESS_ONCE() macro in smp_store_release() and smp_load_acquire()
> with WRITE_ONCE() and READ_ONCE() on x86, arm, arm64, ia64, metag, mips,
> powerpc, s390, sparc and asm-generic since ACCESS_ONCE does not work
> reliably on non-scalar types.
>
> WRITE_ONCE() and READ_ONCE() were introduced in the commits 230fa253df63
> ("kernel: Provide READ_ONCE and ASSIGN_ONCE") and 43239cbe79fc ("kernel:
> Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)").
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire
2015-08-02 15:11 [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire Andrey Konovalov
2015-08-02 16:08 ` Peter Zijlstra
2015-08-02 20:50 ` Davidlohr Bueso
@ 2015-08-03 1:41 ` Michael Ellerman
2015-08-03 6:02 ` Ralf Baechle
3 siblings, 0 replies; 5+ messages in thread
From: Michael Ellerman @ 2015-08-03 1:41 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, 2015-08-02 at 17:11 +0200, Andrey Konovalov wrote:
> Replace ACCESS_ONCE() macro in smp_store_release() and smp_load_acquire()
> with WRITE_ONCE() and READ_ONCE() on x86, arm, arm64, ia64, metag, mips,
> powerpc, s390, sparc and asm-generic since ACCESS_ONCE does not work
> reliably on non-scalar types.
.. and there are no restrictions on the argument to smp_load_acquire(), so it
may be a non-scalar type.
Though from a quick grep it looks like no one is doing that at the moment?
> WRITE_ONCE() and READ_ONCE() were introduced in the commits 230fa253df63
> ("kernel: Provide READ_ONCE and ASSIGN_ONCE") and 43239cbe79fc ("kernel:
> Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)").
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> Changed in v2:
> - Other archs besides x86.
>
> arch/powerpc/include/asm/barrier.h | 4 ++--
> diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
> index 51ccc72..0eca6ef 100644
> --- a/arch/powerpc/include/asm/barrier.h
> +++ b/arch/powerpc/include/asm/barrier.h
> @@ -76,12 +76,12 @@
> do { \
> compiletime_assert_atomic_type(*p); \
> smp_lwsync(); \
> - ACCESS_ONCE(*p) = (v); \
> + WRITE_ONCE(*p, v); \
> } while (0)
>
> #define smp_load_acquire(p) \
> ({ \
> - typeof(*p) ___p1 = ACCESS_ONCE(*p); \
> + typeof(*p) ___p1 = READ_ONCE(*p); \
> compiletime_assert_atomic_type(*p); \
> smp_lwsync(); \
> ___p1; \
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
cheers
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire
2015-08-02 15:11 [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire Andrey Konovalov
` (2 preceding siblings ...)
2015-08-03 1:41 ` Michael Ellerman
@ 2015-08-03 6:02 ` Ralf Baechle
3 siblings, 0 replies; 5+ messages in thread
From: Ralf Baechle @ 2015-08-03 6:02 UTC (permalink / raw)
To: linux-arm-kernel
On Sun, Aug 02, 2015 at 05:11:04PM +0200, Andrey Konovalov wrote:
> diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h
> index 7ecba84..752e0b8 100644
> --- a/arch/mips/include/asm/barrier.h
> +++ b/arch/mips/include/asm/barrier.h
> @@ -133,12 +133,12 @@
> do { \
> compiletime_assert_atomic_type(*p); \
> smp_mb(); \
> - ACCESS_ONCE(*p) = (v); \
> + WRITE_ONCE(*p, v); \
> } while (0)
>
> #define smp_load_acquire(p) \
> ({ \
> - typeof(*p) ___p1 = ACCESS_ONCE(*p); \
> + typeof(*p) ___p1 = READ_ONCE(*p); \
> compiletime_assert_atomic_type(*p); \
> smp_mb(); \
> ___p1; \
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Ralf
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-08-02 15:11 [PATCH v2] arch: use WRITE_ONCE/READ_ONCE in smp_store_release/smp_load_acquire Andrey Konovalov
2015-08-02 16:08 ` Peter Zijlstra
2015-08-02 20:50 ` Davidlohr Bueso
2015-08-03 1:41 ` Michael Ellerman
2015-08-03 6:02 ` Ralf Baechle
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