linux-kernel - Re: [PATCH v3 3/5] bitmap: Add bitmap_alloc(), bitmap_zalloc() and bitmap

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Date:   Tue, 19 Jun 2018 01:52:13 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        agk@...hat.com, Mike Snitzer <snitzer@...hat.com>,
        device-mapper development <dm-devel@...hat.com>,
        shli@...nel.org, linux-raid@...r.kernel.org,
        "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
        Yury Norov <ynorov@...iumnetworks.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Joe Perches <joe@...ches.com>
Subject: Re: [PATCH v3 3/5] bitmap: Add bitmap_alloc(), bitmap_zalloc() and bitmap_free()

On Tue, Jun 19, 2018 at 1:01 AM, Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> On Mon, Jun 18, 2018 at 2:14 PM Andrew Morton <akpm@...ux-foundation.org> wrote:
>>
>> On Mon, 18 Jun 2018 16:10:01 +0300 Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
>>
>> > A lot of code become ugly because of open coding allocations for bitmaps.
>> >
>> > Introduce three helpers to allow users be more clear of intention
>> > and keep their code neat.
>> >
>> > ...
>> >
>> > +unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
>> > +{
>> > +     return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long), flags);
>> > +}
>> > +EXPORT_SYMBOL(bitmap_alloc);
>> > +
>> > +unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
>> > +{
>> > +     return bitmap_alloc(nbits, flags | __GFP_ZERO);
>> > +}
>> > +EXPORT_SYMBOL(bitmap_zalloc);
>> > +
>> > +void bitmap_free(const unsigned long *bitmap)
>> > +{
>> > +     kfree(bitmap);
>> > +}
>> > +EXPORT_SYMBOL(bitmap_free);
>> > +
>>
>> I suggest these functions are small and simple enough to justify
>> inlining them.
>>
>
> We can't as we end up including bitmap.h (by the way of cpumask.h)
> form slab.h, so we gen circular dependency. Maybe if we removed memcg
> stuff from slab.h so we do not need to include workqueue.h...

I will look at it. It might be doable.
Though I dunno what MM people would say about this. Anyone's name
comes to your mind to ask?

-- 
With Best Regards,
Andy Shevchenko