Re: [PATCH] cdrom: do not print info list when there is no cdrom device

[Enze Li <lienze@kylinos.cn>]

On Fri, 8 Apr 2022 06:34:04 -0600
Jens Axboe <axboe@kernel.dk> wrote:

> On 4/8/22 2:42 AM, Enze Li wrote:
> > There is no need to print a list of cdrom entries with blank info
> > when no cdrom device exists.  With this patch applied, we get:
> > 
> > ================================================
> > $ cat /proc/sys/dev/cdrom/info
> > CD-ROM information, Id:cdrom.c 3.20 2003/12/17
> > 
> > No device found.
> > 
> > ================================================  

Hi Jens,

Thanks for your review.

> 
> And what did we get before?

Without the patch, we get:

================================================
$ cat /proc/sys/dev/cdrom/info
CD-ROM information, Id: cdrom.c 3.20 2003/12/17

drive name:	
drive speed:	
drive # of slots:
Can close tray:	
Can open tray:	
Can lock tray:	
Can change speed:
Can select disk:
Can read multisession:
Can read MCN:	
Reports media changed:
Can play audio:	
Can write CD-R:	
Can write CD-RW:
Can read DVD:	
Can write DVD-R:
Can write DVD-RAM:
Can read MRW:	
Can write MRW:	
Can write RAM:	


================================================

> 
> Will this potentially break applications that parse it?
> 

I dunno, is there any way to confirm this thing?  And if this is really
a possibility, does it mean that we cannot make changes?

BTW, could you pls help review the following patch?  I forgot to cc you
and linux-block@list. :)
https://lore.kernel.org/lkml/20220406090337.1116708-1-lienze@kylinos.cn/

Thanks,
Enze