| Message ID | 1478283426-6649-1-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Nov 4, 2016 at 11:17 AM, Mark Rutland <mark.rutland@arm.com> wrote: > For several reasons it is preferable to use {READ,WRITE}_ONCE() rather than > ACCESS_ONCE(). For example, these handle aggregate types, result in shorter > source code, and better document the intended access (which may be useful for > instrumentation features such as the upcoming KTSAN). > > Over a number of patches, most uses of ACCESS_ONCE() in arch/arm64 have been > migrated to {READ,WRITE}_ONCE(). For consistency, and the above reasons, this > patch migrates the final remaining uses. Thanks! Acked-by: Dmitry Vyukov <dvyukov@google.com> > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Will Deacon <will.deacon@arm.com> > --- > arch/arm64/include/asm/percpu.h | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h > index 5394c84..4afb6fc 100644 > --- a/arch/arm64/include/asm/percpu.h > +++ b/arch/arm64/include/asm/percpu.h > @@ -101,16 +101,16 @@ static inline unsigned long __percpu_read(void *ptr, int size) > > switch (size) { > case 1: > - ret = ACCESS_ONCE(*(u8 *)ptr); > + ret = READ_ONCE(*(u8 *)ptr); > break; > case 2: > - ret = ACCESS_ONCE(*(u16 *)ptr); > + ret = READ_ONCE(*(u16 *)ptr); > break; > case 4: > - ret = ACCESS_ONCE(*(u32 *)ptr); > + ret = READ_ONCE(*(u32 *)ptr); > break; > case 8: > - ret = ACCESS_ONCE(*(u64 *)ptr); > + ret = READ_ONCE(*(u64 *)ptr); > break; > default: > BUILD_BUG(); > @@ -123,16 +123,16 @@ static inline void __percpu_write(void *ptr, unsigned long val, int size) > { > switch (size) { > case 1: > - ACCESS_ONCE(*(u8 *)ptr) = (u8)val; > + WRITE_ONCE(*(u8 *)ptr, (u8)val); > break; > case 2: > - ACCESS_ONCE(*(u16 *)ptr) = (u16)val; > + WRITE_ONCE(*(u16 *)ptr, (u16)val); > break; > case 4: > - ACCESS_ONCE(*(u32 *)ptr) = (u32)val; > + WRITE_ONCE(*(u32 *)ptr, (u32)val); > break; > case 8: > - ACCESS_ONCE(*(u64 *)ptr) = (u64)val; > + WRITE_ONCE(*(u64 *)ptr, (u64)val); > break; > default: > BUILD_BUG(); > -- > 2.7.4 >
On Fri, Nov 04, 2016 at 06:17:06PM +0000, Mark Rutland wrote: > For several reasons it is preferable to use {READ,WRITE}_ONCE() rather than > ACCESS_ONCE(). For example, these handle aggregate types, result in shorter > source code, and better document the intended access (which may be useful for > instrumentation features such as the upcoming KTSAN). > > Over a number of patches, most uses of ACCESS_ONCE() in arch/arm64 have been > migrated to {READ,WRITE}_ONCE(). For consistency, and the above reasons, this > patch migrates the final remaining uses. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Will Deacon <will.deacon@arm.com> I'll queue this for 4.10. Thanks.
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index 5394c84..4afb6fc 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -101,16 +101,16 @@ static inline unsigned long __percpu_read(void *ptr, int size) switch (size) { case 1: - ret = ACCESS_ONCE(*(u8 *)ptr); + ret = READ_ONCE(*(u8 *)ptr); break; case 2: - ret = ACCESS_ONCE(*(u16 *)ptr); + ret = READ_ONCE(*(u16 *)ptr); break; case 4: - ret = ACCESS_ONCE(*(u32 *)ptr); + ret = READ_ONCE(*(u32 *)ptr); break; case 8: - ret = ACCESS_ONCE(*(u64 *)ptr); + ret = READ_ONCE(*(u64 *)ptr); break; default: BUILD_BUG(); @@ -123,16 +123,16 @@ static inline void __percpu_write(void *ptr, unsigned long val, int size) { switch (size) { case 1: - ACCESS_ONCE(*(u8 *)ptr) = (u8)val; + WRITE_ONCE(*(u8 *)ptr, (u8)val); break; case 2: - ACCESS_ONCE(*(u16 *)ptr) = (u16)val; + WRITE_ONCE(*(u16 *)ptr, (u16)val); break; case 4: - ACCESS_ONCE(*(u32 *)ptr) = (u32)val; + WRITE_ONCE(*(u32 *)ptr, (u32)val); break; case 8: - ACCESS_ONCE(*(u64 *)ptr) = (u64)val; + WRITE_ONCE(*(u64 *)ptr, (u64)val); break; default: BUILD_BUG();
For several reasons it is preferable to use {READ,WRITE}_ONCE() rather than ACCESS_ONCE(). For example, these handle aggregate types, result in shorter source code, and better document the intended access (which may be useful for instrumentation features such as the upcoming KTSAN). Over a number of patches, most uses of ACCESS_ONCE() in arch/arm64 have been migrated to {READ,WRITE}_ONCE(). For consistency, and the above reasons, this patch migrates the final remaining uses. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/percpu.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)