Re: [PATCH] Add pci_walk_bus function to PCI core (nonrecursive)

[Benjamin Herrenschmidt]

On Thu, 2005-08-18 at 14:33 +1000, Paul Mackerras wrote:
> The PCI error recovery infrastructure needs to be able to contact all
> the drivers affected by a PCI error event, which may mean traversing
> all the devices under a given PCI-PCI bridge.  This patch adds a
> function to the PCI core that traverses all the PCI devices on a PCI
> bus and under any PCI-PCI bridges on that bus (and so on), calling a
> given function for each device.  This provides a way for the error
> recovery code to iterate through all devices that are affected by an
> error event.

 .../...

Note that it's racy vs. removal of devices, but I suspect a good bunch
of the PCI code is. The whole idea that list*_safe routines pay you
anything in that regard need to be shot. Afaik, they are only safe about
the caller removing the current element.

I wonder if it's finally time to implement proper race free list
iterators in the kernel. Not that difficult... A small struct iterator
with a list head and the current elem pointer, and the "interated" list
containing the list itself, a list of iterators and a lock. Iterators
can then be "fixed" up on element removal with a fine grained lock on
list structure access.

Ben.


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