Re: [PATCH] SCSI: explain the hidden scsi_wait_scan Kconfig variable

From: Sam Ravnborg
Date: Thu Jun 18 2009 - 12:57:25 EST


On Thu, Jun 18, 2009 at 03:21:26PM +0000, James Bottomley wrote:
> On Wed, 2009-06-17 at 12:07 +0200, Stefan Richter wrote:
> > People keep sending patches to expose CONFIG_SCSI_WAIT_SCAN as a tunable
> > item. These patches aren't accepted upstream, so let's stop the ongoing
> > irritation of people due to this obscure and strange installed module
> > and its Kconfig option.
> >
> > Signed-off-by: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/scsi/Kconfig | 17 ++++++++++++++++-
> > 1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > Index: b/drivers/scsi/Kconfig
> > ===================================================================
> > --- a/drivers/scsi/Kconfig
> > +++ b/drivers/scsi/Kconfig
> > @@ -259,10 +259,25 @@ config SCSI_SCAN_ASYNC
> > or async on the kernel's command line.
> >
> > config SCSI_WAIT_SCAN
> > - tristate
> > + tristate # No prompt here, this is a hidden option.
>
> Adding comments explaining this is good, I think.
>
> > default m
> > depends on SCSI
> > depends on MODULES
> > + help
> > + Wait until all the async scans are complete. The idea is to use
> > + it in initrd/ initramfs scripts. You modprobe it after all the
> > + modprobes of the root SCSI drivers and it will wait until they
> > + have all finished scanning their buses before allowing the boot
> > + to proceed.
> > +
> > + Of course this does not work if targets boot independently of and
> > + in parallel with the initiator, and/ or with transports with non-
> > + deterministic target discovery schemes, and/ or if a transport
> > + driver does not support scsi_wait_scan.
> > +
> > + Still, this option is not exposed as a prompt because little is
> > + to be gained by disabling it, whereas people who accidentally
> > + switch it off may wonder why their mkinitrd gets into trouble.
>
> But not a help text that can never be shown. Turn this into a comment
> and I'll apply the patch.
>
> The reason is the fact that this could be construed as a detectable bug
> (option with help that can never be displayed) and someone with too much
> time on their hands someday might make a static checker for it.

In another thread we discussed that the help text should be visible when
searching for an invisible symbol.
There are arguments both ways.

Personally I like the help syntax that we one day can benefit from
and would not accept a warning for help text on symbols with no prompt.

Sam
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