Re: [linux-pm] PCI hotplug v.s. suspend

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday 15 June 2009, Alan Stern wrote:
> On Mon, 15 Jun 2009, Alan Jenkins wrote:
> 
> > Alan Stern wrote:
> > > On Mon, 15 Jun 2009, Alan Jenkins wrote:
> > >
> > >   
> > >> Hi,
> > >>
> > >> I triggered a WARNING while hacking on eeepc-laptop's 
> > >> rfkill-by-pci-hotplug.  I saw "Trying to free already-free IRQ" in 
> > >> ath5k_pci_remove(), because the IRQ was already freed by 
> > >> ath5k_pci_suspend().  My changes to eeepc-laptop had allowed the PCI 
> > >> device to be removed while suspended.
> > >>
> > >> Are PCI drivers supposed to handle remove() while suspended?
> > >>     
> > >
> > > Yes.  You found a bug in the driver.  However it's not clear (to me at
> > > least) whether the bug is that the IRQ is freed in the suspend method
> > > or that there's no check for already-freed in the remove method.  My 
> > > guess is the latter.
> > >
> > > Alan Stern
> > >   
> > 
> > The example in Documentation/power/pci.txt shows free_irq() being called
> > in suspend (and request_irq() in resume).  So the problem is in remove().
> 
> I'm not sure whether the example is trustworthy.  There was some
> discussion quite a while ago regarding whether drivers should free
> their IRQs during suspend, but I don't remember what the outcome was.

No, they shouldn't.

That's why we do the entire suspend_device_irqs() thing etc.

Best,
Rafael