[PATCH] scsi_wait_scan: no option appears when configuring for scsi_wait_scan.

[PATCH] scsi_wait_scan: no option appears when configuring for scsi_wait_scan.

[Changli Gao]

FIXBUG: missing comment after tristate leads to no option for
scsci_wait_scan when configuring.

When build kernel, this module is always built if I choose SCSI, and I
can't find any option in the configuration menu, so I can't disable it
or build it into kernel statically. After diving into the kernel source
code, I found no comment after keyword tristate, then I added the
comment and help.

Signed-off-by: Changli Gao <xiaosuo@gmail.com <mailto:xiaosuo@gmail.com>>
----

Kconfig | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- drivers/scsi/Kconfig.orig	2009-06-17 09:52:46.000000000 +0800
+++ drivers/scsi/Kconfig	2009-06-17 09:55:57.000000000 +0800
@@ -259,10 +259,15 @@
 	  or async on the kernel's command line.
 
 config SCSI_WAIT_SCAN
-	tristate
+	tristate "Wait until all the async scans are complete"
 	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 busses before allowing the boot to proceed
 
 menu "SCSI Transports"
 	depends on SCSI

Re: [PATCH] scsi_wait_scan: no option appears when configuring for scsi_wait_scan.

[Matthew Wilcox]

On Wed, Jun 17, 2009 at 10:07:32AM +0800, Changli Gao wrote:
> FIXBUG: missing comment after tristate leads to no option for
> scsci_wait_scan when configuring.

Please search the archives.  Patches along these lines have been rejected
before.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

[PATCH] SCSI: explain the hidden scsi_wait_scan Kconfig variable

[Stefan Richter]

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@s5r6.in-berlin.de>
---
 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.
 	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.
 
 menu "SCSI Transports"
 	depends on SCSI

-- 
Stefan Richter
-=====-==--= -==- =---=
http://arcgraph.de/sr/

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

[Stefan Richter]

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.

PS, references:
http://bugzilla.kernel.org/show_bug.cgi?id=8763
http://bugzilla.kernel.org/show_bug.cgi?id=8872
http://bugzilla.kernel.org/show_bug.cgi?id=9769
and more mailinglist references than you can shake a stick at, yet 
nobody is aware of.
-- 
Stefan Richter
-=====-==--= -==- =---=
http://arcgraph.de/sr/

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

[Changli Gao]

On Wed, Jun 17, 2009 at 6:07 PM, Stefan
Richter<stefanr@s5r6.in-berlin.de> 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.
Aha, I really like this, and think it works. :)


-- 
Regards，
Changli Gao(xiaosuo@gmail.com)

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

[James Bottomley]

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@s5r6.in-berlin.de>
> ---
>  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.

James

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

[Sam Ravnborg]

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@s5r6.in-berlin.de>
> > ---
> >  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

[PATCH update 1] SCSI: explain the hidden scsi_wait_scan Kconfig variable

[Stefan Richter]

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 the unconditionally installed module and its
Kconfig symbol.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
update 1: more precise wording

 drivers/scsi/Kconfig |   15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Index: b/drivers/scsi/Kconfig
===================================================================
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -259,10 +259,23 @@ config SCSI_SCAN_ASYNC
 	  or async on the kernel's command line.
 
 config SCSI_WAIT_SCAN
-	tristate
+	tristate  # No prompt here, this is an invisible symbol.
 	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.  (This method is not applicable if targets boot
+	  independently in parallel with the initiator, or with transports
+	  with non-deterministic target discovery schemes, or if a transport
+	  driver does not support scsi_wait_scan.)
+
+	  This symbol 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.
 
 menu "SCSI Transports"
 	depends on SCSI

-- 
Stefan Richter
-=====-==--= -==- =--=-
http://arcgraph.de/sr/

[PATCH update 2] SCSI: explain the hidden scsi_wait_scan Kconfig variable

[Stefan Richter]

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 the unconditionally installed module and its
Kconfig symbol.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
update 1: more precise wording
update 2: same as comment instead of help (pick what you like better)

 drivers/scsi/Kconfig |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Index: b/drivers/scsi/Kconfig
===================================================================
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -259,10 +259,21 @@ config SCSI_SCAN_ASYNC
 	  or async on the kernel's command line.
 
 config SCSI_WAIT_SCAN
-	tristate
+	tristate  # No prompt here, this is an invisible symbol.
 	default m
 	depends on SCSI
 	depends on MODULES
+# scsi_wait_scan is a loadable module which waits 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.  (This method is not applicable if targets boot independently in
+# parallel with the initiator, or with transports with non-deterministic target
+# discovery schemes, or if a transport driver does not support scsi_wait_scan.)
+#
+# This symbol 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.
 
 menu "SCSI Transports"
 	depends on SCSI

-- 
Stefan Richter
-=====-==--= -==- =--=-
http://arcgraph.de/sr/

Re: [PATCH update 2] SCSI: explain the hidden scsi_wait_scan Kconfig variable

[Alan Cox]

On Thu, 18 Jun 2009 21:03:23 +0200 (CEST)
Stefan Richter <stefanr@s5r6.in-berlin.de> 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 the unconditionally installed module and its
> Kconfig symbol.

How about the other possibility. People keepmaking it tunable because it
makes sense for it to be tunable. Far better IMHO to make it tunable "if
EMBEDDED"

Re: [PATCH update 2] SCSI: explain the hidden scsi_wait_scan Kconfig variable

[Matthew Wilcox]

On Mon, Jun 22, 2009 at 09:57:01AM +0100, Alan Cox wrote:
> On Thu, 18 Jun 2009 21:03:23 +0200 (CEST)
> Stefan Richter <stefanr@s5r6.in-berlin.de> 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 the unconditionally installed module and its
> > Kconfig symbol.
> 
> How about the other possibility. People keepmaking it tunable because it
> makes sense for it to be tunable. Far better IMHO to make it tunable "if
> EMBEDDED"

It doesn't make sense for it to be tunable.

All it does is control whether or not scsi_wait_scan.ko is built.
Everyone who's complained about it has been of the form "I turned off
all modules, but this module gets built anyway".  For them, the answer
is simple: Don't run "make modules_install".

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."