Re: [linux-usb-devel] usb-storage bug in 2.6.12-rc3

[Greg KH <greg@kroah.com>]

On Fri, Apr 29, 2005 at 09:35:52PM +0200, Oliver Neukum wrote:
> Am Freitag, 29. April 2005 21:28 schrieb David Brownell:
> > On Friday 29 April 2005 11:23 am, Roman Kagan wrote:
> > > 
> > > ... instead of trying to make sure the attributes are available via
> > > sysfs at hotplug time, we can use another means to pass them to hotplug:
> > > we can add a routine, which, when called from the .hotplug function
> > > and given pointers to struct attribute and struct device, would add
> > > environment variable
> > > 
> > > SYSFS_attrName=attrValue
> > 
> > Color me amused.  That was the original way to pass information
> > to hotplug agents ... back then (2.4.0.test10 or so), there was
> > usually no other way to export the relevant data.
> 
> Does that mean it was a bad idea? At least it makes sure that
> there are less race conditions.
> 
> > I'd rather just guarantee that the sysfs device were fully
> > constructed (attributes and all) before the driver binding and
> > hotplug stages of enumeration started.  That's been a problem
> > all along, and that's what those recent changes were supposed
> > to be addressing.
> 
> Even if you can make sure they had been set up before the script
> started, how do you make sure they are still around?

You can't guarantee that they will not have been removed, but by at
least saying that "the attributes will be created before you will be
called", you let userspace go a lot faster :)

thanks,

greg k-h


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