linux-kernel - Re: [PATCH] iio: adc: ad799x: constify attribute

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Message-ID: <e9dd2273-f051-0540-28b5-ac8e9bab6b0b@kernel.org>
Date:   Wed, 29 Mar 2017 22:36:38 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     SIMRAN SINGHAL <singhalsimran0@...il.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        outreachy-kernel <outreachy-kernel@...glegroups.com>
Subject: Re: [PATCH] iio: adc: ad799x: constify attribute_group structures

On 29/03/17 22:28, SIMRAN SINGHAL wrote:
> On Thu, Mar 30, 2017 at 2:43 AM, Jonathan Cameron <jic23@...nel.org> wrote:
>> On 28/03/17 21:07, simran singhal wrote:
>>> Check for attribute_group structures that are only stored in the
>>> event_attrs filed of iio_info structure. As the event_attrs field of
>>> iio_info structures is constant, so these attribute_group structures can
>>> also be declared constant.
>>> Done using coccinelle:
>>>
>>> @r1 disable optional_qualifier @
>>> identifier i;
>>> position p;
>>> @@
>>> static struct attribute_group i@p = {...};
>>>
>>> @ok1@
>>> identifier r1.i;
>>> position p;
>>> struct iio_info x;
>>> @@
>>> x.event_attrs=&i@p;
>>>
>>> @bad@
>>> position p!={r1.p,ok1.p};
>>> identifier r1.i;
>>> @@
>>> i@p
>>>
>>> @depends on !bad disable optional_qualifier@
>>> identifier r1.i;
>>> @@
>>> static
>>> +const
>>> struct attribute_group i={...};
>>>
>>> @depends on !bad disable optional_qualifier@
>>> identifier r1.i;
>>> @@
>>> +const
>>> struct attribute_group i;
>>>
>>> File size before:
>>>    text    data     bss     dec     hex filename
>>>   26051     464       0   26515    6793 drivers/iio/adc/ad799x.o
>>>
>>> File size after:
>>>    text          data     bss     dec     hex filename
>>>   26115           400       0   26515    6793 drivers/iio/adc/ad799x.o
>>>
>>> Signed-off-by: simran singhal <singhalsimran0@...il.com>
>> Applied to the togreg branch of iio.git and pushed out as testing
>> for the autobuilders to play with it.
>>
> 
> But my tree is up-to-date and I also test it before sending.
this is standard practice.  I build as well before pushing out, but
I only do one or two configurations of one or two architectures.
The autobuilders are a set of large servers that Intel run as a service
to the kernel community.

Typically they'll run a few hundred builds for dozens of processor architectures
+ a much more extensive set of static tests than most kernel developers
are set up to run.  Here things will almost certainly be fine, but
I've been wrong before!

The only thing is I tend to push out in the evening then go to bed before
the results come in, then might not get to it for a day or so to push out
as togreg.  This tree I am happy to rebase - that is I can drop or fixup
patches with issues.  The togreg branch is the one that people often
base new work on, so if I change the tree under them all sorts of nasty
merge issues can occur.

This is why most trees that ultimately go upstream are non rebasing -
but a lot of people now have a testing branch which is deliberately
unofficial - people shouldn't use it to base their trees on as it
is temporary for build test purposes.

Greg has one as well (I assume this is what it is for), he just tends
to be quicker about dealing with whatever comes up than I am so
doesn't explicitly mention it when he takes patches.

https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/log/?h=staging-testing

So it's nothing to worry about. I just put that note in so people
don't wonder why their patch isn't immediately present in the public
togreg branch of iio.git.

Jonathan
> 
>> Thanks,
>>
>> Jonathan
>>> ---
>>>  drivers/iio/adc/ad799x.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
>>> index 9704090..22426ae 100644
>>> --- a/drivers/iio/adc/ad799x.c
>>> +++ b/drivers/iio/adc/ad799x.c
>>> @@ -520,7 +520,7 @@ static struct attribute *ad799x_event_attributes[] = {
>>>       NULL,
>>>  };
>>>
>>> -static struct attribute_group ad799x_event_attrs_group = {
>>> +static const struct attribute_group ad799x_event_attrs_group = {
>>>       .attrs = ad799x_event_attributes,
>>>  };
>>>
>>>
>>