linux-kernel - Re: [PATCH 2/9] pci: add pci_bridge_release_unused_res and pci_bus_release_unused_bridge

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Date:	Wed, 16 Dec 2009 12:49:15 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Alex Chiang <achiang@...com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	Ingo Molnar <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH 2/9] pci: add pci_bridge_release_unused_res and
 pci_bus_release_unused_bridge_res

On Fri, 27 Nov 2009 23:35:14 -0800
Yinghai Lu <yinghai@...nel.org> wrote:

> 
> so later we could use it to release small resource before pci assign
> unassign res
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> 
> ---
>  drivers/pci/setup-bus.c |  114
> +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 113
> insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/pci/setup-bus.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/setup-bus.c
> +++ linux-2.6/drivers/pci/setup-bus.c
> @@ -609,6 +609,118 @@ void __ref pci_bus_assign_resources(cons
>  }
>  EXPORT_SYMBOL(pci_bus_assign_resources);
>  
> +static void release_children_resource(struct resource *r)

release_child_resources?

> +{
> +	struct resource *p;
> +	resource_size_t size;
> +
> +	p = r->child;
> +	while (p) {
> +		release_children_resource(p);
> +		release_resource(p);
> +		printk(KERN_DEBUG "PCI: release child resource
> %pRt\n", p);
> +		/* need to restore size, and keep flags */
> +		size = resource_size(p);
> +		p->start = 0;
> +		p->end = size - 1;
> +		p = r->child;
> +	}
> +}

Also seems like it should go into resource.c instead?

> +
> +static void pci_bridge_release_unused_res(struct pci_bus *bus,
> +					  unsigned long type)
> +{
> +	int idx;
> +	bool changed = false;
> +	struct pci_dev *dev;
> +	struct resource *r;
> +	unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
> +				  IORESOURCE_PREFETCH;
> +
> +	/* for pci bridges res only */
> +	dev = bus->self;
> +	for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_BRIDGE_RESOURCES
> + 3;
> +	    idx++) {
> +		r = &dev->resource[idx];
> +		if ((r->flags & type_mask) != type)
> +			continue;
> +		if (!r->parent)
> +			continue;
> +		/*
> +		 * if there are children under that, we should
> release them
> +		 *  all
> +		 */
> +		release_children_resource(r);
> +		if (!release_resource(r)) {
> +			dev_printk(KERN_DEBUG, &dev->dev,
> +				 "resource %d %pRt released\n", idx,
> r);
> +			/* keep the old size */
> +			r->end = resource_size(r) - 1;
> +			r->start = 0;
> +			r->flags = 0;
> +			changed = true;
> +		}
> +	}
> +
> +	if (changed) {
> +		if (type & IORESOURCE_PREFETCH) {
> +			/* avoiding touch the one without PREF */
> +			type = IORESOURCE_PREFETCH;
> +		}
> +		__pci_setup_bridge(bus, type);
> +	}
> +}
> +
> +/*
> + * try to release pci bridge resources that is from leaf bridge,
> + * so we can allocate big new one later
> + * check:
> + *    0: only release the bridge and only the bridge is leaf
> + *    1: release all down side bridge for third shoot
> + */
> +static void __ref pci_bus_release_unused_bridge_res(struct pci_bus
> *bus,
> +						    unsigned long
> type,
> +						    int check_leaf)
> +{
> +	struct pci_dev *dev;
> +	bool is_leaf_bridge = true;
> +
> +	list_for_each_entry(dev, &bus->devices, bus_list) {
> +		struct pci_bus *b = dev->subordinate;
> +		if (!b)
> +			continue;
> +
> +		switch (dev->class >> 8) {
> +		case PCI_CLASS_BRIDGE_CARDBUS:
> +			is_leaf_bridge = false;
> +			break;
> +
> +		case PCI_CLASS_BRIDGE_PCI:
> +		default:
> +			is_leaf_bridge = false;
> +			if (!check_leaf)
> +				pci_bus_release_unused_bridge_res(b,
> type,
> +							 check_leaf);
> +			break;
> +		}
> +	}
> +
> +	/* The root bus? */
> +	if (!bus->self)
> +		return;
> +
> +	switch (bus->self->class >> 8) {
> +	case PCI_CLASS_BRIDGE_CARDBUS:
> +		break;
> +
> +	case PCI_CLASS_BRIDGE_PCI:
> +	default:
> +		if ((check_leaf && is_leaf_bridge) || !check_leaf)
> +			pci_bridge_release_unused_res(bus, type);
> +		break;
> +	}
> +}
> +
>  static void pci_bus_dump_res(struct pci_bus *bus)
>  {

The idea here seems good, of allowing reallocation of bridge windows
when the space is insufficient.  Would be good if Linus could check out
this series though.

-- 
Jesse Barnes, Intel Open Source Technology Center
--
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