Re: [PATCH v2 5/5] Input: evdev - Switch to bitmap_zalloc()

From: Joe Perches <joe@perches.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Yury Norov <ynorov@caviumnetworks.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	agk@redhat.com, Mike Snitzer <snitzer@redhat.com>,
	dm-devel@redhat.com, shli@kernel.org, linux-raid@vger.kernel.org,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	linux-input <linux-input@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: [PATCH v2 5/5] Input: evdev - Switch to bitmap_zalloc()
Date: Sat, 16 Jun 2018 12:16:28 -0700	[thread overview]
Message-ID: <0a3d86d7746792a2f848cef386941fc182653515.camel@perches.com> (raw)
In-Reply-To: <CAHp75VcxYPCLYq1J8qqjPdgDdQnWDgZKkavmyEWD8GNxcW2mWg@mail.gmail.com>

On Sat, 2018-06-16 at 21:45 +0300, Andy Shevchenko wrote:
> On Sat, Jun 16, 2018 at 12:46 AM Yury Norov <ynorov@caviumnetworks.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.