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Date: Mon, 26 Oct 2009 17:57:56 -0600
From: Bjorn Helgaas <bjorn.helgaas@...com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] pci: only release that resource index is less than 3
On Mon, 2009-10-26 at 14:23 -0700, Yinghai Lu wrote:
> ===================================================================
> --- linux-2.6.orig/drivers/pci/setup-bus.c
> +++ linux-2.6/drivers/pci/setup-bus.c
> @@ -322,33 +322,54 @@ static void pci_bridge_check_ranges(stru
> }
> }
>
> -/* Helper function for sizing routines: find first available
> - bus resource of a given type. Note: we intentionally skip
> - the bus resources which have already been assigned (that is,
> - have non-NULL parent resource). */
> -static struct resource *find_free_bus_resource(struct pci_bus *bus, unsigned long type)
> +void pci_bridge_release_not_used_res(struct pci_bus *bus)
> {
> int i;
> struct resource *r;
> unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
> IORESOURCE_PREFETCH;
>
> - for (i = 0; i < PCI_BUS_NUM_RESOURCES; i++) {
> + /* for pci bridges res only */
> + for (i = 0; i < 3; i++) {
I think the "i = 0; i < 3" part is to check the bridge apertures, i.e.,
the I/O base/limit, the memory base/limit, and the prefetchable memory
base/limit. Right? We need some way to indicate that more clearly than
using a hard-coded "3".
> r = bus->resource[i];
> - if (r == &ioport_resource || r == &iomem_resource)
> - continue;
> - if (r && (r->flags & type_mask) == type) {
> + if (r && (r->flags & type_mask)) {
> if (!r->parent)
> - return r;
> + continue;
> /*
> * if there is no child under that, we should release
> * and use it. don't need to reset it, pbus_size_* will
> * set it again
> */
> if (!r->child && !release_resource(r))
We got this resource pointer out of a struct pci_bus, and we release it
here. We must have previously done a request_resource(),
allocate_resource(), or similar. Where does that happen? Are the
requests and releases nested correctly?
I would think that somewhere, we would be doing a request_resource() and
assigning the resource to pci_bus->resource[x]. But there are very few
assignments to the pci_bus resources:
setup_resource (only for "pci=use_crs")
pci_read_bridge_bases (just a copy from upstream bus resources)
pci_alloc_child_bus (copy from upstream bridge resources)
pci_create_bus (set to &ioport_resource or &iomem_resource)
My guess is that this release_resource() releases something we copied
from the bridge in pci_alloc_child_bus(). But that doesn't seem right,
because we aren't changing the bridge programming here.
Maybe I'm being confused by the fact that we find the resource pointer
from the pci_bus table, but that's only a pointer to the actual struct
resource that lives in the pci_dev of the upstream bridge.
Bjorn
> - return r;
> + dev_printk(KERN_DEBUG, &bus->dev,
> + "resource %d %s %pR released\n", i,
> + (r->flags & IORESOURCE_IO) ? "io: " :
> + ((r->flags & IORESOURCE_PREFETCH)?
> + "pref mem":"mem:"),
> + r);
> }
> }
> +}
> +EXPORT_SYMBOL(pci_bridge_release_not_used_res);
> +
> +/* Helper function for sizing routines: find first available
> + bus resource of a given type. Note: we intentionally skip
> + the bus resources which have already been assigned (that is,
> + have non-NULL parent resource). */
> +static struct resource *find_free_bus_resource(struct pci_bus *bus, unsigned long type)
> +{
> + int i;
> + struct resource *r;
> + unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
> + IORESOURCE_PREFETCH;
> +
> + for (i = 0; i < PCI_BUS_NUM_RESOURCES; i++) {
> + r = bus->resource[i];
> + if (r == &ioport_resource || r == &iomem_resource)
> + continue;
> + if (r && (r->flags & type_mask) == type && !r->parent)
> + return r;
> + }
> return NULL;
> }
>
> @@ -588,6 +609,41 @@ void __ref pci_bus_size_bridges(struct p
> }
> EXPORT_SYMBOL(pci_bus_size_bridges);
>
> +static void pci_bus_release_bridges_not_used_res(struct pci_bus *bus)
> +{
> + struct pci_dev *dev;
> +
> + 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:
> + break;
> +
> + case PCI_CLASS_BRIDGE_PCI:
> + default:
> + pci_bus_release_bridges_not_used_res(b);
> + 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:
> + pci_bridge_release_not_used_res(bus);
> + break;
> + }
> +}
> +
> void __ref pci_bridge_assign_resources(const struct pci_dev *bridge)
> {
> struct pci_bus *b;
> @@ -687,6 +743,11 @@ pci_assign_unassigned_resources(void)
> {
> struct pci_bus *bus;
>
> + /* Try to release bridge resources, that there is not child under it */
> + list_for_each_entry(bus, &pci_root_buses, node) {
> + pci_bus_release_bridges_not_used_res(bus);
> + }
> +
> /* Depth first, calculate sizes and alignments of all
> subordinate buses. */
> list_for_each_entry(bus, &pci_root_buses, node) {
> Index: linux-2.6/drivers/pci/hotplug/pciehp_pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/hotplug/pciehp_pci.c
> +++ linux-2.6/drivers/pci/hotplug/pciehp_pci.c
> @@ -171,6 +171,7 @@ int pciehp_unconfigure_device(struct slo
> }
> pci_dev_put(temp);
> }
> + pci_bridge_release_not_used_res(parent);
>
> return rc;
> }
> Index: linux-2.6/include/linux/pci.h
> ===================================================================
> --- linux-2.6.orig/include/linux/pci.h
> +++ linux-2.6/include/linux/pci.h
> @@ -759,6 +759,7 @@ int pci_vpd_truncate(struct pci_dev *dev
> void pci_bridge_assign_resources(const struct pci_dev *bridge);
> void pci_bus_assign_resources(const struct pci_bus *bus);
> void pci_bus_size_bridges(struct pci_bus *bus);
> +void pci_bridge_release_not_used_res(struct pci_bus *bus);
> int pci_claim_resource(struct pci_dev *, int);
> void pci_assign_unassigned_resources(void);
> void pdev_enable_device(struct pci_dev *);
--
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