Missing piece from as659

Missing piece from as659

[Matthew Wilcox]

Alan, you didn't cc the pci mailing list on the original patch.
http://www.ussg.iu.edu/hypermail/linux/kernel/0602.2/2673.html

You only fix pci_get_subsys; pci_get_class has the same bug.

If it is a bug, of course.  It's not clear to me whether it's permissible
to call pci_dev_put under a spinlock or not.  That boils down to whether
kobject ->release methods can sleep or not.  That isn't documented in
Documentation/kobject.txt and I rather think it should be.

Re: Missing piece from as659

[Alan Stern]

On Fri, 24 Feb 2006, Matthew Wilcox wrote:

> Alan, you didn't cc the pci mailing list on the original patch.
> http://www.ussg.iu.edu/hypermail/linux/kernel/0602.2/2673.html

This seems to be a blind spot of mine.  Yours is the second complaint in 
two days about patches I failed to CC to the appropriate 
maintainer/mailing-list...

> You only fix pci_get_subsys; pci_get_class has the same bug.

Please submit a similar bugfix for pci_get_class, then.  I just noticed 
the log messages from pci_get_subsys because that's the routine that 
happened to run on the machine I was testing.

> If it is a bug, of course.  It's not clear to me whether it's permissible
> to call pci_dev_put under a spinlock or not.  That boils down to whether
> kobject ->release methods can sleep or not.  That isn't documented in
> Documentation/kobject.txt and I rather think it should be.

It is a bug, but it has been ignored up until recently.  Within the last 
month or two, Greg added a might_sleep() call to put_device().  It 
wouldn't hurt to do the same thing to kobject_put(), or maybe just 
kobject_release().

Alan Stern

Re: Missing piece from as659

[Greg KH]

On Fri, Feb 24, 2006 at 12:53:01PM -0500, Alan Stern wrote:
> On Fri, 24 Feb 2006, Matthew Wilcox wrote:
> > http://www.ussg.iu.edu/hypermail/linux/kernel/0602.2/2673.html
> > If it is a bug, of course.  It's not clear to me whether it's permissible
> > to call pci_dev_put under a spinlock or not.  That boils down to whether
> > kobject ->release methods can sleep or not.  That isn't documented in
> > Documentation/kobject.txt and I rather think it should be.
> 
> It is a bug, but it has been ignored up until recently.  Within the last 
> month or two, Greg added a might_sleep() call to put_device().  It 
> wouldn't hurt to do the same thing to kobject_put(), or maybe just 
> kobject_release().

kobject_put() will not necessarily sleep, it's only the device_put that
will, due to the locking in the driver core.

thanks,

greg k-h