Re: [patch V4 part 1 06/36] compiler: Simple READ/WRITE_ONCE() implementations

[Alexandre Chartre]

On 5/5/20 3:16 PM, Thomas Gleixner wrote:
> READ/WRITE_ONCE_NOCHECK() is required for atomics in code which cannot be
> instrumented like the x86 int3 text poke code. As READ/WRITE_ONCE() is
> undergoing a rewrite, provide __{READ,WRITE}_ONCE_SCALAR().
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
>   include/linux/compiler.h |    8 ++++++++
>   1 file changed, 8 insertions(+)

Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>

alex.

> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -313,6 +313,14 @@ unsigned long read_word_at_a_time(const
>   	__u.__val;					\
>   })
>   
> +#define __READ_ONCE_SCALAR(x)				\
> +	(*(const volatile typeof(x) *)&(x))
> +
> +#define __WRITE_ONCE_SCALAR(x, val)			\
> +do {							\
> +	*(volatile typeof(x) *)&(x) = val;		\
> +} while (0)
> +
>   /**
>    * data_race - mark an expression as containing intentional data races
>    *