Re: [PATCH v3 05/11] PCI: Add pci_reachable_set()

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Sep 11, 2025 at 03:56:50PM -0400, Donald Dutile wrote:

> Yes, and for clarify, I'd prefer the fcn name to be 'pci_reachable_bus_set()' so
> it's clear it (or its callers) are performing an intra-bus reachable result,
> and not doing inter-bus reachability checking, although returning a 256-bit
> devfns without a domain prefix indirectly indicates it.

Sure:

/**
 * pci_reachable_bus_set - Generate a bitmap of devices within a reachability set
 * @start: First device in the set
 * @devfns: Output set of devices on the bus reachable from start
 * @reachable: Callback to tell if two devices can reach each other
 *
 * Compute a bitmap @defvfns where every set bit is a device on the bus of
 * @start that is reachable from the @start device, including the start device.
 * Reachability between two devices is determined by a callback function.
 *
 * This is a non-recursive implementation that invokes the callback once per
 * pair. The callback must be commutative::
 *
 *    reachable(a, b) == reachable(b, a)
 *
 * reachable() can form a cyclic graph::
 *
 *    reachable(a,b) == reachable(b,c) == reachable(c,a) == true
 *
 * Since this function is limited to a single bus the largest set can be 256
 * devices large.
 */
void pci_reachable_bus_set(struct pci_dev *start,
			   struct pci_reachable_set *devfns,
			   bool (*reachable)(struct pci_dev *deva,
					     struct pci_dev *devb))

Thanks,
Jason