On Tue, 28 Mar 2017, kan.li...@intel.com wrote:
> From: Kan Liang <kan.li...@intel.com>
>
> There is no exported kernel interfaces which can flip a MSR bit. It has
> to do read-modify-write operation on the MSR through rd/wrmsr*
> interfaces. But the method is not atomic.
>
> There is already __flip_bit support. Just rename and expose it.
This function is not atomic either. Protection has to be provided by the
caller.
> -static inline int __flip_bit(u32 msr, u8 bit, bool set)
> +int msr_flip_bit(u32 msr, u8 bit, bool set)
> {
> struct msr m, m1;
> int err = -EINVAL;
> @@ -85,6 +85,7 @@ static inline int __flip_bit(u32 msr, u8 bit, bool set)
>
> return 1;
> }
> +EXPORT_SYMBOL_GPL(msr_flip_bit);
That export is not required. The call site is always built in.
Thanks,
tglx
