netdev - Re: [patch net-next 1/3] idr: Add new APIs to support unsigned long

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Date:   Tue, 29 Aug 2017 09:57:11 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Chris Mi <chrism@...lanox.com>
Cc:     Hannes Frederic Sowa <hannes@...essinduktion.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jhs@...atatu.com" <jhs@...atatu.com>,
        "xiyou.wangcong@...il.com" <xiyou.wangcong@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "mawilcox@...rosoft.com" <mawilcox@...rosoft.com>
Subject: Re: [patch net-next 1/3] idr: Add new APIs to support unsigned long

Tue, Aug 29, 2017 at 09:34:47AM CEST, chrism@...lanox.com wrote:
>Hi,
>
>> -----Original Message-----
>> From: Hannes Frederic Sowa [mailto:hannes@...essinduktion.org]
>> Sent: Tuesday, August 29, 2017 3:14 PM
>> To: Chris Mi <chrism@...lanox.com>
>> Cc: netdev@...r.kernel.org; jhs@...atatu.com;
>> xiyou.wangcong@...il.com; jiri@...nulli.us; davem@...emloft.net;
>> mawilcox@...rosoft.com
>> Subject: Re: [patch net-next 1/3] idr: Add new APIs to support unsigned long
>> 
>> Hello,
>> 
>> Chris Mi <chrism@...lanox.com> writes:
>> 
>> > The following new APIs are added:
>> >
>> > int idr_alloc_ext(struct idr *idr, void *ptr, unsigned long *index,
>> >                   unsigned long start, unsigned long end, gfp_t gfp);
>> > static inline void *idr_remove_ext(struct idr *idr, unsigned long id);
>> > static inline void *idr_find_ext(const struct idr *idr, unsigned long
>> > id); void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long
>> > id); void *idr_get_next_ext(struct idr *idr, unsigned long *nextid);
>> >
>> > Signed-off-by: Chris Mi <chrism@...lanox.com>
>> > Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>> > ---
>> >  include/linux/idr.h        | 16 ++++++++++
>> >  include/linux/radix-tree.h |  3 ++
>> >  lib/idr.c                  | 56 +++++++++++++++++++++++++++++++++++
>> >  lib/radix-tree.c           | 73
>> ++++++++++++++++++++++++++++++++++++++++++++++
>> >  4 files changed, 148 insertions(+)
>> >
>> 
>> [...]
>> 
>> > +int idr_alloc_ext(struct idr *idr, void *ptr, unsigned long *index,
>> > +		  unsigned long start, unsigned long end, gfp_t gfp) {
>> > +	void __rcu **slot;
>> > +	struct radix_tree_iter iter;
>> > +
>> > +	if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
>> > +		return -EINVAL;
>> > +
>> > +	radix_tree_iter_init(&iter, start);
>> > +	slot = idr_get_free_ext(&idr->idr_rt, &iter, gfp, end);
>> > +	if (IS_ERR(slot))
>> > +		return PTR_ERR(slot);
>> > +
>> > +	radix_tree_iter_replace(&idr->idr_rt, &iter, slot, ptr);
>> > +	radix_tree_iter_tag_clear(&idr->idr_rt, &iter, IDR_FREE);
>> > +
>> > +	if (index)
>> > +		*index = iter.index;
>> > +	return 0;
>> > +}
>> > +EXPORT_SYMBOL_GPL(idr_alloc_ext);
>> 
>> Can you express idr_alloc in terms of idr_alloc_ext? Same for most of the
>> other functions (it seems that signed int was used as return value to indicate
>> error cases, thus it should be easy to map those).
>In idr_alloc(), we have the following check:
>
>        if (WARN_ON_ONCE(start < 0))
>                return -EINVAL;
>
>But in idr_alloc_ext(), since we are using unsigned long, we needn't such check.

You can just check and call idr_alloc_ext then to do the actual work.