Re: [Xen-devel] [PATCH RFC 11/12] time: Convert xen_read_wallclock() to use timespec64

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 27 Oct 2014, pang.xunlei wrote:
> The kernel uses 32-bit signed value(time_t) for seconds since 
> 1970-01-01:00:00:00, so it
> will overflow at 2038-01-19 03:14:08 on 32-bit systems. We call this "2038 
> safety" issue.
> 
> As part of addressing 2038 safety for in-kernel uses, this patch creates no 
> functional change
> in existing users, converts xen_read_wallclock() to use timespec64 instead of 
> timespec.
> 
> Signed-off-by: pang.xunlei <pang.xunlei@xxxxxxxxxx>

Please CC xen-devel@xxxxxxxxxxxxxxxxxxxx for Xen related patches.


>  arch/x86/xen/time.c |   31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
> index cf1b591..2ce064a 100644
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -169,20 +169,33 @@ static cycle_t xen_clocksource_get_cycles(struct 
> clocksource *cs)
>       return xen_clocksource_read();
>  }
>  
> -static void xen_read_wallclock(struct timespec *ts)
> +static void xen_read_wallclock(struct timespec64 *ts)
>  {
> +     struct timespec ts32;
>       struct shared_info *s = HYPERVISOR_shared_info;
>       struct pvclock_wall_clock *wall_clock = &(s->wc);
>          struct pvclock_vcpu_time_info *vcpu_time;
>  
>       vcpu_time = &get_cpu_var(xen_vcpu)->time;
> -     pvclock_read_wallclock(wall_clock, vcpu_time, ts);
> +     /*
> +      * TODO: [2038 safety] pvclock_read_wallclock() should be changed
> +      * to use timespec64 for 2038 safety as soon as possible.
> +      */
> +     pvclock_read_wallclock(wall_clock, vcpu_time, &ts32);
> +     *ts = timespec_to_timespec64(ts32);
>       put_cpu_var(xen_vcpu);
>  }
>  
> +/*
> + * TODO: [2038 safety] xen_get_wallclock() should be changed to use
> + * timespec64 for 2038 safety as soon as possible.
> + */
>  static void xen_get_wallclock(struct timespec *now)

At this point shouldn't you convert xen_get_wallclock to timespec64 too?


>  {
> -     xen_read_wallclock(now);
> +     struct timespec64 now64;
> +
> +     xen_read_wallclock(&now64);
> +     *now = timespec64_to_timespec(now64);
>  }
>  
>  static int xen_set_wallclock(const struct timespec *now)
> @@ -485,8 +498,7 @@ static const struct pv_time_ops xen_time_ops __initconst 
> = {
>  static void __init xen_time_init(void)
>  {
>       int cpu = smp_processor_id();
> -     struct timespec tp;
> -     struct timespec64 tp64;
> +     struct timespec64 tp;
>  
>       clocksource_register_hz(&xen_clocksource, NSEC_PER_SEC);
>  
> @@ -497,14 +509,9 @@ static void __init xen_time_init(void)
>               xen_clockevent = &xen_vcpuop_clockevent;
>       }
>  
> -     /*
> -      * Set initial system time with full resolution.
> -      * TODO: [2038 safety] xen_read_wallclock() should be changed to use
> -      * timespec64 for 2038 safety as soon as possible.
> -      */
> +     /* Set initial system time with full resolution. */
>       xen_read_wallclock(&tp);
> -     tp64 = timespec_to_timespec64(tp);
> -     do_settimeofday(&tp64);
> +     do_settimeofday(&tp);
>  
>       setup_force_cpu_cap(X86_FEATURE_TSC);
>  
> -- 
> 1.7.9.5
> 
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