[libvirt] [PATCH v2 1/2] virhostuptime: Introduce virHostBootTimeInit()

[Daniel P. Berrangé]

On Thu, Dec 19, 2019 at 12:25:00PM +0100, Michal Privoznik wrote:
> The idea is to offer callers an init function that they can call
> independently to ensure that the global variables get
> initialized.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virhostuptime.c | 13 ++++++++++++-
>  src/util/virhostuptime.h |  3 +++
>  3 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index a7b1ef23bc..257ce00615 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2194,6 +2194,7 @@ virHostMemSetParameters;
>  
>  
>  # util/virhostuptime.h
> +virHostBootTimeInit;
>  virHostGetBootTime;
>  
>  
> diff --git a/src/util/virhostuptime.c b/src/util/virhostuptime.c
> index 8c49c3d40e..6c251c0d2d 100644
> --- a/src/util/virhostuptime.c
> +++ b/src/util/virhostuptime.c
> @@ -126,7 +126,8 @@ virHostGetBootTimeOnceInit(void)
>  int
>  virHostGetBootTime(unsigned long long *when)
>  {
> -    if (virOnce(&virHostGetBootTimeOnce, virHostGetBootTimeOnceInit) < 0)
> +    if (bootTime == 0 &&
> +        virHostBootTimeInit() < 0)

The bootTime==0 check is not required & technical a data race.
virHostBootTimeInit should be a no-op if it has already been
invoked

>          return -1;
>  
>      if (bootTimeErrno) {
> @@ -137,3 +138,13 @@ virHostGetBootTime(unsigned long long *when)
>      *when = bootTime;
>      return 0;
>  }
> +
> +
> +int
> +virHostBootTimeInit(void)
> +{
> +    if (virOnce(&virHostGetBootTimeOnce, virHostGetBootTimeOnceInit) < 0)
> +        return -1;
> +
> +    return 0;
> +}
> diff --git a/src/util/virhostuptime.h b/src/util/virhostuptime.h
> index 7e2c4c0c81..1ac638fd6e 100644
> --- a/src/util/virhostuptime.h
> +++ b/src/util/virhostuptime.h
> @@ -25,3 +25,6 @@
>  int
>  virHostGetBootTime(unsigned long long *when)
>      G_GNUC_NO_INLINE;
> +
> +int
> +virHostBootTimeInit(void);
> -- 
> 2.24.1
> 
> --
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> libvir-list at redhat.com
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Regards,
Daniel
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