linux-kernel - Re: [PATCH 0/2] scsi: remove orphaned modular code from non-modular drivers

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Message-ID: <20160328151014.GR16831@windriver.com>
Date:	Mon, 28 Mar 2016 11:10:14 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	James Bottomley <jejb@...ux.vnet.ibm.com>
CC:	<linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	<linux-m68k@...r.kernel.org>, <linux-mips@...ux-mips.org>,
	<linux-scsi@...r.kernel.org>
Subject: Re: [PATCH 0/2] scsi: remove orphaned modular code from non-modular
 drivers

[Re: [PATCH 0/2] scsi: remove orphaned modular code from non-modular drivers] On 27/03/2016 (Sun 22:31) James Bottomley wrote:

> On Sun, 2016-03-27 at 13:00 -0400, Paul Gortmaker wrote:
> > In the ongoing audit/cleanup of non-modular code needlessly using 
> > modular infrastructure, the SCSI subsystem fortunately only contains 
> > two instances that I detected.  Both are for legacy drivers that 
> > predate the git epoch, so cleary there is no demand for converting 
> > these drivers to be tristate.
> > 
> > For anyone new to the underlying goal of this cleanup, we are trying 
> > to not use module support for code that isn't buildable as a module
> > since:
> > 
> >  (1) it is easy to accidentally write unused module_exit and remove
> > code
> >  (2) it can be misleading when reading the source, thinking it can be
> >      modular when the Makefile and/or Kconfig prohibit it
> >  (3) it requires the include of the module.h header file which in
> > turn
> >      includes nearly everything else, thus adding to CPP overhead.
> >  (4) it gets copied/replicated into other code and spreads like
> > weeds.
> 
> I don't really buy any of these as being credible issues for the
> ancient drivers, so there doesn't appear to be an real benefit to this
> conversion; however, besides the danger of touching old stuff, there
> are some down sides:

Thanks James for your review and always interesting/alternative
viewpoints.  You seem pretty clear in your conviction here, so I won't
bother making counter points ; best we just agree to disagree, and I
won't bother you with these patches again.

Paul.
--

> 
> > -MODULE_DESCRIPTION("Sun3x ESP SCSI driver");
> > -MODULE_AUTHOR("Thomas Bogendoerfer (tsbogend@...ha.franken.de)");
> > -MODULE_LICENSE("GPL");
> > -MODULE_VERSION(DRV_VERSION);
> 
> These tags are usefully greppable for drivers, regardless of whether
> they generate actual kernel side information.
> 
> > We explicitly disallow a driver unbind, since that doesn't have a
> > sensible use case anyway, and it allows us to drop the ".remove"
> > code for non-modular drivers.
> 
> That's bogus.  I use bind and unbind a lot for testing built in drivers
> but the usual user use case is for resetting the devices.
> 
> > Build tested for mips (jazz) and m68k (sun3x) on 4.6-rc1 to ensure no
> > silly typos crept in.
> 
> For trivial changes, build testing is not really sufficient: a
> significant fraction of them break something that isn't spotted by the
> reviewers.  For the older drivers, this isn't discovered for months to
> years and then someone has to go digging back through all the so called
> trivial changes to find which one it was.
> 
> James
>