linux-kernel - Re: [PATCH 3/9] drbd: Drop unnecessary static

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Date:   Tue, 27 Jun 2017 16:49:52 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Roland Kammerer <roland.kammerer@...bit.com>,
        Jens Axboe <axboe@...nel.dk>
Cc:     Julia Lawall <Julia.Lawall@...6.fr>,
        Philipp Reisner <philipp.reisner@...bit.com>,
        kernel-janitors@...r.kernel.org,
        Lars Ellenberg <lars.ellenberg@...bit.com>,
        drbd-dev@...ts.linbit.com, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/9] drbd: Drop unnecessary static

On Fri, May 5, 2017 at 12:19 AM, Roland Kammerer
<roland.kammerer@...bit.com> wrote:
> On Thu, May 04, 2017 at 10:10:48PM +0200, Julia Lawall wrote:
>> Drop static on a local variable, when the variable is initialized before
>> any use, on every possible execution path through the function.  The static
>> has no benefit, and dropping it reduces the code size.
>>
>> The semantic patch that fixes this problem is as follows:
>> (http://coccinelle.lip6.fr/)
>>
>> // <smpl>
>> @bad exists@
>> position p;
>> identifier x;
>> type T;
>> @@
>>
>> static T x@p;
>> ...
>> x = <+...x...+>
>>
>> @@
>> identifier x;
>> expression e;
>> type T;
>> position p != bad.p;
>> @@
>>
>> -static
>>  T x@p;
>>  ... when != x
>>      when strict
>> ?x = e;
>> // </smpl>
>>
>> The change in code size is indicates by the following output from the size
>> command.
>>
>> before:
>>    text    data     bss     dec     hex filename
>>   67299    2291    1056   70646   113f6 drivers/block/drbd/drbd_nl.o
>>
>> after:
>>    text    data     bss     dec     hex filename
>>   67283    2291    1056   70630   113e6 drivers/block/drbd/drbd_nl.o
>>
>> Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
>>
>> ---
>>  drivers/block/drbd/drbd_nl.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
>> index 02255a0..ad0fcb4 100644
>> --- a/drivers/block/drbd/drbd_nl.c
>> +++ b/drivers/block/drbd/drbd_nl.c
>> @@ -2294,7 +2294,7 @@ static bool conn_ov_running(struct drbd_connection *connection)
>>  static enum drbd_ret_code
>>  check_net_options(struct drbd_connection *connection, struct net_conf *new_net_conf)
>>  {
>> -     static enum drbd_ret_code rv;
>> +     enum drbd_ret_code rv;
>>       struct drbd_peer_device *peer_device;
>>       int i;
>
> Yes, that already got dropped for drbd9 and is obviously correct for
> in-tree drbd8.
>
> Signed-off-by: Roland Kammerer <roland.kammerer@...bit.com>
>
> Regards, rck

Which tree should this go through? Jens, I think yours?

Thanks!

-Kees

-- 
Kees Cook
Pixel Security