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SubjectRe: [PATCH 1/8] cgroups: add res_counter_write_u64() API
On Mon, Jan 16, 2012 at 02:27:13PM +0200, Kirill A. Shutemov wrote:
> On Fri, Jan 13, 2012 at 07:13:47PM +0100, Frederic Weisbecker wrote:
> > Extend the resource counter API with a mirror of res_counter_read_u64() to
> > make it handy to update a resource counter value from a cgroup subsystem
> > u64 value file.
>
> I still think it worth to have two versions of res_counter_write_u64().
> From my POV, it's clean enough, but consistent with res_counter_read_u64()
> and faster on 64bit system.
>
> What do you think?

Yeah right let's do this. Can I get your signed-off-by to take the below?

Thanks.

>
> ---
> diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
> index c9d625c..1b3fe05 100644
> --- a/include/linux/res_counter.h
> +++ b/include/linux/res_counter.h
> @@ -82,6 +82,8 @@ int res_counter_memparse_write_strategy(const char *buf,
> int res_counter_write(struct res_counter *counter, int member,
> const char *buffer, write_strategy_fn write_strategy);
>
> +void res_counter_write_u64(struct res_counter *counter, int member, u64 val);
> +
> /*
> * the field descriptors. one for each member of res_counter
> */
> diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> index 6d269cc..aad4ddb 100644
> --- a/kernel/res_counter.c
> +++ b/kernel/res_counter.c
> @@ -167,12 +167,27 @@ int res_counter_memparse_write_strategy(const char *buf,
> return 0;
> }
>
> +#if BITS_PER_LONG == 32
> +void res_counter_write_u64(struct res_counter *counter, int member, u64 val)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&counter->lock, flags);
> + *res_counter_member(counter, member) = val;
> + spin_unlock_irqrestore(&counter->lock, flags);
> +}
> +#else
> +void res_counter_write_u64(struct res_counter *counter, int member, u64 val)
> +{
> + *res_counter_member(counter, member) = val;
> +}
> +#endif
> +
> int res_counter_write(struct res_counter *counter, int member,
> const char *buf, write_strategy_fn write_strategy)
> {
> char *end;
> - unsigned long flags;
> - unsigned long long tmp, *val;
> + unsigned long long tmp;
>
> if (write_strategy) {
> if (write_strategy(buf, &tmp))
> @@ -182,9 +197,8 @@ int res_counter_write(struct res_counter *counter, int member,
> if (*end != '\0')
> return -EINVAL;
> }
> - spin_lock_irqsave(&counter->lock, flags);
> - val = res_counter_member(counter, member);
> - *val = tmp;
> - spin_unlock_irqrestore(&counter->lock, flags);
> +
> + res_counter_write_u64(counter, member, tmp);
> +
> return 0;
> }
> --
> Kirill A. Shutemov


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