[v2] time: Introduce jiffies64_to_msecs()

there is a similar helper in net/netfilter/nf_tables_api.c,
this maybe become a common request someday, so move it to
time.c

Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
 v1-->v2: using jiffies64_to_msecs in nf_tables_api.c

 include/linux/jiffies.h       |  1 +
 kernel/time/time.c            | 10 ++++++++++
 net/netfilter/nf_tables_api.c |  4 +---
 3 files changed, 12 insertions(+), 3 deletions(-)

On Thu, Feb 28, 2019 at 01:13:26PM +0800, Li RongQing wrote:
> there is a similar helper in net/netfilter/nf_tables_api.c,
> this maybe become a common request someday, so move it to
> time.c
> 
> Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
> Signed-off-by: Li RongQing <lirongqing@baidu.com>

Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

This is touching kernel/time.c bits, which is far from my realm.

What should I do with this? I can just place it in nf-next.git if I
get an ACK to do so. Otherwise, please just take this if this looks
good to you.

Thanks!

> ---
>  v1-->v2: using jiffies64_to_msecs in nf_tables_api.c
> 
>  include/linux/jiffies.h       |  1 +
>  kernel/time/time.c            | 10 ++++++++++
>  net/netfilter/nf_tables_api.c |  4 +---
>  3 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
> index fa928242567d..1b6d31da7cbc 100644
> --- a/include/linux/jiffies.h
> +++ b/include/linux/jiffies.h
> @@ -297,6 +297,7 @@ static inline u64 jiffies_to_nsecs(const unsigned long j)
>  }
>  
>  extern u64 jiffies64_to_nsecs(u64 j);
> +extern u64 jiffies64_to_msecs(u64 j);
>  
>  extern unsigned long __msecs_to_jiffies(const unsigned int m);
>  #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
> diff --git a/kernel/time/time.c b/kernel/time/time.c
> index 2edb5088a70b..0083eb711fb7 100644
> --- a/kernel/time/time.c
> +++ b/kernel/time/time.c
> @@ -719,6 +719,16 @@ u64 jiffies64_to_nsecs(u64 j)
>  }
>  EXPORT_SYMBOL(jiffies64_to_nsecs);
>  
> +u64 jiffies64_to_msecs(const u64 j)
> +{
> +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
> +	return (MSEC_PER_SEC / HZ) * j;
> +#else
> +	return div_u64(j * HZ_TO_MSEC_NUM, HZ_TO_MSEC_DEN);
> +#endif
> +}
> +EXPORT_SYMBOL(jiffies64_to_msecs);
> +
>  /**
>   * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
>   *
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index e1a88ba2249e..8763b2798788 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -3184,9 +3184,7 @@ static int nf_msecs_to_jiffies64(const struct nlattr *nla, u64 *result)
>  
>  static __be64 nf_jiffies64_to_msecs(u64 input)
>  {
> -	u64 ms = jiffies64_to_nsecs(input);
> -
> -	return cpu_to_be64(div_u64(ms, NSEC_PER_MSEC));
> +	return cpu_to_be64(jiffies64_to_msecs(input));
>  }
>  
>  static int nf_tables_fill_set(struct sk_buff *skb, const struct nft_ctx *ctx,
> -- 
> 2.16.2
>

On Fri, Mar 8, 2019 at 7:55 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> On Thu, Feb 28, 2019 at 01:13:26PM +0800, Li RongQing wrote:
> > there is a similar helper in net/netfilter/nf_tables_api.c,
> > this maybe become a common request someday, so move it to
> > time.c
> >
> > Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
>
> Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
>
> This is touching kernel/time.c bits, which is far from my realm.
>
> What should I do with this? I can just place it in nf-next.git if I
> get an ACK to do so. Otherwise, please just take this if this looks
> good to you.

Acked-by: John Stultz <john.stultz@linaro.org>

On Fri, Mar 08, 2019 at 08:52:10AM -0800, John Stultz wrote:
> On Fri, Mar 8, 2019 at 7:55 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> >
> > On Thu, Feb 28, 2019 at 01:13:26PM +0800, Li RongQing wrote:
> > > there is a similar helper in net/netfilter/nf_tables_api.c,
> > > this maybe become a common request someday, so move it to
> > > time.c
> > >
> > > Signed-off-by: Zhang Yu <zhangyu31@baidu.com>
> > > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> >
> > Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
> >
> > This is touching kernel/time.c bits, which is far from my realm.
> >
> > What should I do with this? I can just place it in nf-next.git if I
> > get an ACK to do so. Otherwise, please just take this if this looks
> > good to you.
> 
> Acked-by: John Stultz <john.stultz@linaro.org>

Thanks. Now applied.