Subject: Re: [PATCHv2] qla2xxx: Correct compilation issues when CONFIG_MOUDLES=n.

From: Andrew Vasquez <[email-masked]>
Date: Tue, 15 Sep 2009 11:26:09 -0700

On Tue, 15 Sep 2009, Greg KH wrote:

> On Tue, Sep 15, 2009 at 10:47:11AM -0500, James Bottomley wrote:
> > On Tue, 2009-09-15 at 08:33 -0700, Greg KH wrote:
> > > On Sat, Sep 12, 2009 at 09:30:07AM -0500, James Bottomley wrote:
> > > > On Fri, 2009-09-11 at 21:33 -0700, Greg KH wrote:
> > > > > On Fri, Sep 11, 2009 at 07:56:23PM -0700, Andrew Vasquez wrote:
> > > > > > On Fri, 11 Sep 2009, Greg KH wrote:
> > > > > > 
> > > > > > > On Fri, Sep 11, 2009 at 05:38:08PM -0700, Andrew Vasquez wrote:
> > > > > > > > Randy Dunlap noted:
> > > > > > > > 
> > > > > > > >   when CONFIG_MODULES=n:
> > > > > > > > 
> > > > > > > > 	drivers/scsi/qla2xxx/qla_os.c:2685: error: dereferencing pointer to incomplete type
> > > > > > > > 
> > > > > > > >   in
> > > > > > > > 
> > > > > > > > 	kobject_uevent_env(&(&vha->hw->pdev->driver->driver)->owner->mkobj.kobj,
> > > > > > > > 		KOBJ_CHANGE, envp);
> > > > > > > > 
> > > > > > > > Trigger kobject event on the 'struct device' hanging off the pci_dev.
> > > > > > > 
> > > > > > > Um, why?  What are you trying to do here?  kobject change should not be
> > > > > > > for a device, or a "normal" kobject.
> > > > > > > 
> > > > > > > What do you expect userspace to do with this?  Where have you documented
> > > > > > > it?
> > > > > > 
> > > > > > The purpose was described here:
> > > > > > 
> > > > > > 	http://article.gmane.org/gmane.linux.scsi/54155
> > > > > > 
> > > > > > Basically we'd like to instruct user-space to retrieve a blob of data
> > > > > > automatically.
> > > > > 
> > > > > Hm, like a firmware object perhaps?
> > > > > 
> > > > > > Original implementation used the kboject hanging off
> > > > > > the module which does not exist when CONFIG_MODULES=n.  It was
> > > > > > suggested that perhaps an alternative would be to use 'struct device'
> > > > > > kobj.  Any tips on how to trigger such a driver-specific event,
> > > > > > perhaps a dedicated kobject exported by the driver itself???
> > > > > 
> > > > > Why not use the firmware interface for it, that is what it is designed
> > > > > for, and you will not have to craft any new udev rules.
> > > > 
> > > > The data is going the wrong way to use the current firmware interface,
> > > > which is designed to load data from userspace into the kernel.  For this
> > > > interface, we want the data to go the other way (i.e. the kernel has a
> > > > blob of dump data it would like userspace to save if it can).
> > > 
> > > Ick.
> > 
> > It's a natural debugging event ... the user can simply program the
> > system to discard the dump.
> > 
> > > > I'd be amenable to updating the firmware interface to do this, but it
> > > > looks like adding a completely new codepath, which it's not clear even
> > > > belongs there.
> > > 
> > > Well, I don't think it deserves a kobject change event, as that means
> > > something a bit different to userspace today, right?
> > 
> > Well, the documentation (in include/linux/kobject.h) does say that
> > KOBJ_CHANGED is the dumping ground for events that don't match anything
> > else, which this one seems to qualify as.  What else do you suggest?
> 
> Ok, I can't think of anything else at the moment, sorry.
> 
> This is using a binary sysfs file, right?

Yes, the userspace tool retrieves the dump from a binary sysfs node:

	/sys/class/scsi_host/hostX/device/fw_dump

-- AV