Re: [PATCH] scsi: Delete scsi_use_blk_mq

From: Ewan D. Milne
Date: Wed Feb 12 2020 - 11:10:55 EST


On Tue, 2020-02-11 at 11:50 +0000, John Garry wrote:
> On 10/02/2020 22:37, Bart Van Assche wrote:
> > On 2/10/20 9:33 AM, John Garry wrote:
> > > -module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR |
> > > S_IRUGO);
>
> Hi Bart,
>
> > Will this change cause trouble to shell scripts that set or read this
> > parameter (/sys/module/scsi_mod/parameters/use_blk_mq)?
>
> The entry in Documentation/admin-guide/kernel-parameters.txt is gone for
> 2 years now.
>
> And it is not an archaic module param, it was introduced 6 years ago. As
> such, I'd say that if a shell script was setup to access this parameter,
> then it would prob also pre-check if it exists and gracefully accept
> that it may not.
>
> I will also note that there is still scsi_sysfs.c:show_use_blk_mq(),
> which would stay.
>
> What will the
> > impact be on systems where scsi_mod.use_blk_mq=Y is passed by GRUB to
> > the kernel at boot time, e.g. because it has been set in the
> > GRUB_CMDLINE_LINUX variable in /etc/default/grub?
>
> The kernel should any params that does not recognize.
>
>
> Having said all that, I don't feel too strongly about deleting this -
> it's only some tidy-up.
>
> Thanks,
> John
>

I think we should remove it. It is not good to have a kernel parameter
that people used to be able to set to "N" that no longer does that.

-Ewan