From: Joe Perches <joe@perches.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Bhumika Goyal <bhumirks@gmail.com>,
Julia Lawall <julia.lawall@lip6.fr>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] nvdimm: constify device_type structures
Date: Tue, 24 Jan 2017 18:49:29 -0800 [thread overview]
Message-ID: <1485312569.12563.52.camel@perches.com> (raw)
In-Reply-To: <CAPcyv4i7-vT+-VqU2n4bxrtcwrYtJ5rcVg3=bf5gCx-YRe3HkA@mail.gmail.com>
On Tue, 2017-01-24 at 18:40 -0800, Dan Williams wrote:
> On Tue, Jan 24, 2017 at 6:37 PM, Joe Perches <joe@perches.com> wrote:
> > On Wed, 2017-01-25 at 00:54 +0530, Bhumika Goyal wrote:
> > > Declare device_type structure as const as it is only stored in the
> > > type field of a device structure. This field is of type const, so add
> > > const to declaration of device_type structure.
> > >
> > > File size before:
> > > text data bss dec hex filename
> > > 19278 3199 16 22493 57dd nvdimm/namespace_devs.o
> > >
> > > File size after:
> > > text data bss dec hex filename
> > > 19929 3160 16 23105 5a41 nvdimm/namespace_devs.o
> >
> > Fine, but are you sure about the sizes?
> >
> > It seems odd the text went up 651 bytes
> > while the data went down just 39 bytes.
> >
>
> Right, the size data wasn't why I applied it. It was the general rule
> of "make function pointer data read-only whenever possible to
> eliminate a kernel attack vector".
Exactly the correct reason it's a fine patch and one
that should be applied.
> Bhumika, you might want to mention
> this as the motivating reason to apply the patch if you do more of
> these changes.
Regardless, the object sizes are still odd.
The config should be mentioned because actually,
the commonly compiles sizes reported are not correct.
with an x86-64 defconfig I get:
$ size drivers/nvdimm/namespace_devs.o*
text data bss dec hex filename
14615 519 16 15150 3b2e drivers/nvdimm/namespace_devs.o.new
14439 695 16 15150 3b2e drivers/nvdimm/namespace_devs.o.old
next prev parent reply other threads:[~2017-01-25 2:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 19:24 [PATCH] nvdimm: constify device_type structures Bhumika Goyal
2017-01-24 19:58 ` Dan Williams
2017-01-25 2:37 ` Joe Perches
2017-01-25 2:40 ` Dan Williams
2017-01-25 2:49 ` Joe Perches [this message]
2017-01-25 6:49 ` Julia Lawall
2017-01-25 16:01 ` Joe Perches
2017-01-25 16:04 ` Julia Lawall
2017-01-25 16:16 ` Bhumika Goyal
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