Re: [PATCH -next] bcache: use DEFINE_MUTEX() for mutex lock

From: Dan Carpenter
Date: Thu Apr 29 2021 - 01:57:04 EST


On Wed, Apr 28, 2021 at 09:19:26PM +0500, Muhammad Usama Anjum wrote:
> On Tue, 2021-04-06 at 02:17 +0500, Muhammad Usama Anjum wrote:
> > On Mon, 2021-04-05 at 22:02 +0800, Coly Li wrote:
> > > On 4/5/21 6:14 PM, Zheng Yongjun wrote:
> > > > mutex lock can be initialized automatically with DEFINE_MUTEX()
> > > > rather than explicitly calling mutex_init().
> > > >
> > > > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > > > Signed-off-by: Zheng Yongjun <zhengyongjun3@xxxxxxxxxx>
> > >
> > > NACK. This is not the first time people try to "fix" this location...
> > >
> > > Using DEFINE_MUTEX() does not gain anything for us, it will generate
> > > unnecessary extra size for the bcache.ko.
> > > ines.
> >
> > How can the final binary have larger size by just static declaration?
> > By using DEFINE_MUTEX, the mutex is initialized at compile time. It'll
> > save initialization at run time and one line of code will be less also
> > from text section.
> >
> > #### with no change (dynamic initialization)
> > size drivers/md/bcache/bcache.ko
> > text data bss dec hex filename
> > 187792 25310 152 213254 34106 drivers/md/bcache/bcache.ko
> >
> > #### with patch applied (static initialization)
> > text data bss dec hex filename
> > 187751 25342 120 213213 340dd drivers/md/bcache/bcache.ko
> >
> > Module's binary size has decreased by 41 bytes with the path applied
> > (x86_64 arch).
> >
> Anybody has any thoughts on it?
>

I think you're right and the response is puzzling. But who cares? It's
a small thing. Leave it and move on.

regards,
dan carpenter