Re: [PATCH 1/3] scsi_dh: Add modalias support for SCSI targets

[Chandra Seetharaman <sekharan@us.ibm.com>]

Hi James,

Are your concerns answered ?

Hannes, Kay,

Is the description related to bus notify BIND DEVICE issue clear now ?

Please respond :)

chandra
On Wed, 2009-04-08 at 11:08 -0400, Peter Jones wrote:
> On 04/07/2009 04:59 PM, James Bottomley wrote:
> > On Fri, 2009-04-03 at 15:43 -0700, Chandra Seetharaman wrote:
> >> Hi James,
> >>
> >> Do you still have any concerns (after Peter's response) ?
> > 
> > Yes, the basic concerns still remain:
> > 
> >      1. You're forcing autoload now even if the user isn't running
> >         dm ... this is going to cause problems with non-dm based path
> >         handlers
> 
> (Chandra covered this pretty well, so I'll leave it be.)
> 
> >      2. autoloading in this fashion is essentially trying to work around
> >         a problem in the initrd tools.  The kernel isn't the right place
> >         to implement the fix.
> 
> This seems backwards to me.  It's not trying to work around a problem
> in the initrd tools; it's trying to avoid creating one by making this
> subsystem unlike others.
> 
> The point of having modaliases is to allow the kernel to announce that it's
> got a hardware device and notify the userland that appropriate modules should
> be loaded.  That's exactly what we've done here.  What we're trying to avoid
> in the initrd tools is having to have a special handler for this subsystem;
> instead, we'd much rather use the generic mechanism that already exists for
> this purpose.
> 
> > The risks of this approach seem very high, and the rewards pretty small.
> 
> Can you please explain what the high risks you're thinking of are?  I'm not
> clear on what undesirable behavior you expect to occur.
> 
> The reward is that scsi targets behave exactly like most other types of
> hardware and kernel modules in this regard, without having to write special
> probing for this subsystem in the userland and special handling for loading
> these modules.  That's a pretty big win for maintainability.
>