Messages in this thread | | | Date | Sun, 12 Jun 2016 18:25:12 +0800 | From | Minfei Huang <> | Subject | Re: [PATCH] pvclock: introduce seqcount-like API |
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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@redhat.com> > --- > 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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