On 06/09/16 at 01:23P, Paolo Bonzini wrote:
> The version field in struct pvclock_vcpu_time_info basically implements
> a seqcount. Wrap it with the usual read_begin and read_retry functions,
> and use these APIs instead of peppering the code with smp_rmb()s.
> While at it, change it to the more pedantically correct virt_rmb().
>
> With this change, __pvclock_read_cycles can be simplified noticeably.
Hi, Paolo.
Thanks for accepting my patches in your repo.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/entry/vdso/vclock_gettime.c | 25 +++++------------------
> arch/x86/include/asm/pvclock.h | 39 +++++++++++++++++++++---------------
> arch/x86/kernel/pvclock.c | 17 ++++++----------
> 3 files changed, 34 insertions(+), 47 deletions(-)
>
> diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
> index 7c1c89598688..0ee92db1e9f3 100644
> --- a/arch/x86/include/asm/pvclock.h
> +++ b/arch/x86/include/asm/pvclock.h
> @@ -25,6 +25,24 @@ void pvclock_resume(void);
>
> void pvclock_touch_watchdogs(void);
>
> +static __always_inline
> +unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
It's better to use type unsigned int, instead of unsigned which is
complained by script checkpatch.
Thanks
Minfei
> +{
> + unsigned version = src->version & ~1;
Ditto.
> + /* Make sure that the version is read before the data. */
> + virt_rmb();
> + return version;
> +}
> +
> +static __always_inline
> +bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
> + unsigned version)
Ditto.
Thanks
Minfei
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