linux-kernel - Re: [PATCH v2 5/5] Input: evdev

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Message-ID: <0a3d86d7746792a2f848cef386941fc182653515.camel@perches.com>
Date:   Sat, 16 Jun 2018 12:16:28 -0700
From:   Joe Perches <joe@...ches.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Yury Norov <ynorov@...iumnetworks.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        agk@...hat.com, Mike Snitzer <snitzer@...hat.com>,
        dm-devel@...hat.com, shli@...nel.org, linux-raid@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input <linux-input@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v2 5/5] Input: evdev - Switch to bitmap_zalloc()

On Sat, 2018-06-16 at 21:45 +0300, Andy Shevchenko wrote:
> On Sat, Jun 16, 2018 at 12:46 AM Yury Norov <ynorov@...iumnetworks.com> wrote:
> > On Fri, Jun 15, 2018 at 04:20:17PM +0300, Andy Shevchenko wrote:
> > > Switch to bitmap_zalloc() to show clearly what we are allocating.
> > > Besides that it returns pointer of bitmap type instead of opaque void *.
> 
> 
> > > +       mem = bitmap_alloc(maxbit, GFP_KERNEL);
> > >         if (!mem)
> > >                 return -ENOMEM;
> > 
> > But in commit message you say you switch to bitmap_zalloc(). IIUC
> > bitmap_alloc() is OK here. But could you please update comment to
> > avoid confusing.
> 
> There are two places, one with alloc, another with zalloc.
> I will clarify this in commit message of next version.
> 
> > > +       mask = bitmap_zalloc(cnt, GFP_KERNEL);
> > >         if (!mask)
> > >                 return -ENOMEM;
> > > 
> > >         error = bits_from_user(mask, cnt - 1, codes_size, codes, compat);
> > 
> > If my understanding of bits_from_user() correct, here you can also use
> > bitmap_alloc(), true?

Also it might be useful to have a separate bitmap_from_user
to alloc and copy.