Re: Re: Latest bk kernel does not properly free PCI IO & MEM allocations

[Rajesh Shah <rajesh.shah@intel.com>]

On Sun, Mar 13, 2005 at 12:49:42AM +0000, prarit wrote:
> 
> I'll go back to work and pull out the oops' etc.
> 
> > Anyway, I'll add the basic, NULL out the pointer and check for it patch
> > to the tree soon, so that your oops should not happen anymore.
> 
> Thanks Greg :)  I've tested with that patch and it
> seems better.  IMO though, we still have a glitch
> in PCI.  I'm not convinced that it should be calling
> pci_free_resources at all.  
> 
Note that ia64 arch code calls pci_claim_resources() at bus
scan time (in pcibios_fixup_bus()). This adds the resources
in pci_dev structure to the resource list, even before the
corresponding driver is loaded. It is fairly common for a
device driver to then call pci_request_regions() when it is
loaded. This causes a new resource descriptor to be allocated
and added to the resource list.  For example, on my tiger4
ia64 system, /proc/iomem shows:

<snip>
f9000000-fbffffff : PCI Bus 0000:00
  f9ff0000-f9ff03ff : 0000:00:1d.7
    f9ff0000-f9ff03ff : ehci_hcd
  fa000000-faffffff : 0000:01:01.0
  fbfa0000-fbfbffff : 0000:01:01.0
  fbfd0000-fbfd0fff : 0000:01:01.0
  fbfe0000-fbffffff : 0000:01:00.0
    fbfe0000-fbffffff : e1000
<snip>

Since we have 2 resource descriptors for the same resource in
some cases, they both do need to be removed at device remove
time. However, I saw only 1 resource in your /proc/iomem (which
was presumably after the driver had loaded). I wonder if this is
the problem in this case.

In any case, claiming and freeing pci resources needs wider
cleanup. See

http://marc.theaimsgroup.com/?l=linux-kernel&m\x110841094228134&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m\x110842019012889&w=2

for related discussions.

Rajesh


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