On 26/09/2014 08:00, Tiejun Chen wrote:
> We can use get_cpu() and put_cpu() to replace
> preempt_disable()/cpu = smp_processor_id() and
> preempt_enable() for slightly better code.
>
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
> arch/x86/kernel/kvmclock.c | 19 ++++++++-----------
> 1 file changed, 8 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index d9156ce..0bf3467 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -59,13 +59,12 @@ static void kvm_get_wallclock(struct timespec *now)
>
> native_write_msr(msr_kvm_wall_clock, low, high);
>
> - preempt_disable();
> - cpu = smp_processor_id();
> + cpu = get_cpu();
>
> vcpu_time = &hv_clock[cpu].pvti;
> pvclock_read_wallclock(&wall_clock, vcpu_time, now);
>
> - preempt_enable();
> + put_cpu();
> }
>
> static int kvm_set_wallclock(const struct timespec *now)
> @@ -107,11 +106,10 @@ static unsigned long kvm_get_tsc_khz(void)
> int cpu;
> unsigned long tsc_khz;
>
> - preempt_disable();
> - cpu = smp_processor_id();
> + cpu = get_cpu();
> src = &hv_clock[cpu].pvti;
> tsc_khz = pvclock_tsc_khz(src);
> - preempt_enable();
> + put_cpu();
> return tsc_khz;
> }
>
> @@ -284,23 +282,22 @@ int __init kvm_setup_vsyscall_timeinfo(void)
>
> size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
>
> - preempt_disable();
> - cpu = smp_processor_id();
> + cpu = get_cpu();
>
> vcpu_time = &hv_clock[cpu].pvti;
> flags = pvclock_read_flags(vcpu_time);
>
> if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
> - preempt_enable();
> + put_cpu();
> return 1;
> }
>
> if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
> - preempt_enable();
> + put_cpu();
> return ret;
> }
>
> - preempt_enable();
> + put_cpu();
>
> kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
> #endif
>
Thanks, applied at last.
Paolo
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