Linus Torvalds wrote:
>
> On Fri, 18 Dec 2009, Yinghai Lu wrote:
>> so later we could use it to release small resource before pci assign unassign res
>
> However, I think this one is wrong.
>
>> +static void release_child_resources(struct resource *r)
>> +{
>> + struct resource *p;
>> + resource_size_t size;
>> +
>> + p = r->child;
>> + while (p) {
>> + release_child_resources(p);
>> + release_resource(p);
>
> So not only is this releasing resources that aren't necessarily PCI
> devices, it's releasing the whole tree - regardless of how they were
> allocated and initialized. That makes me nervous to begin with. It's in
> the wrong file.
>
> But the locking is crap too!
>
> You need to hold the resource lock for the whole operation - you can't
> just walk the resource tree and release them.
>
> And once you do that, then using "release_resrouce()" is the wrong thing,
> since it turns into just "__release_resource()" and you notice that that
> walks the chain looking for them - which makes it pointless to have
> _another_ outer loop that walks the chain to release them!
>
> So you'd need to
>
> - move this to kernel/resource.c
>
> - do it all under 'write_lock(&resource_lock);'
>
> - stop the silly double list loop, and just do it as a single loop that
> does
>
> p = old->parent->child;
> old->parent = NULL;
> while (p) {
> struct resource *tmp = p;
> p = p->sibling;
>
> .. do whatever you do to free tmp ..
> }
>
> and it's much simpler, more efficient, has the rigth locking, and is in
> the right place.
ok, please check attached is right or not
>
> That said, it's still unclear if you can ever do this! Why would the PCI
> layer be allowed to release ACPI resources int he tree, for example?
>
> So I can see fixing the _implementation_ issues I have like above, but I'd
> still be nervous about the whole concept of the patch..
those code are only called during early stage when pci_assign unassigned, and pcie hotplug under the pcie port.
also that is the pci_try_num is default to 1, and only be changed by pci=try=2 etc. only second try start to call
those functions.
Thanks
Yinghai
Subject: [PATCH 2/12] pci: add pci_bridge_release_unused_res and pci_bus_release_unused_bridge_res -v3
so later we could use it to release small resource before pci assign unassign res
-v2: change name to release_child_resources according to Jesse
-v3: according to Linus, move release_child_resources to resource.c
also need to put the lock around them all to avoid recursive deep.
(my test case only have one level that need to be released)
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
---
drivers/pci/setup-bus.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/ioport.h | 1
kernel/resource.c | 30 +++++++++++++++
3 files changed, 125 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
@@ -209,7 +209,6 @@ static void pci_setup_bridge_mmio_pref(s
l = (region.start >> 16) & 0xfff0;
l |= region.end & 0xfff00000;
if (res->flags & IORESOURCE_MEM_64) {
- pref_mem64 = 1;
bu = upper_32_bits(region.start);
lu = upper_32_bits(region.end);
}
@@ -608,6 +607,100 @@ void __ref pci_bus_assign_resources(cons
}
EXPORT_SYMBOL(pci_bus_assign_resources);
+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_child_resources(r);
+ if (!release_resource(r)) {
+ dev_printk(KERN_DEBUG, &dev->dev,
+ "resource %d %pR 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)
{
int i;
Index: linux-2.6/include/linux/ioport.h
===================================================================
--- linux-2.6.orig/include/linux/ioport.h
+++ linux-2.6/include/linux/ioport.h
@@ -112,6 +112,7 @@ extern struct resource iomem_resource;
extern int request_resource(struct resource *root, struct resource *new);
extern int release_resource(struct resource *new);
+void release_child_resources(struct resource *new);
extern void reserve_region_with_split(struct resource *root,
resource_size_t start, resource_size_t end,
const char *name);
Index: linux-2.6/kernel/resource.c
===================================================================
--- linux-2.6.orig/kernel/resource.c
+++ linux-2.6/kernel/resource.c
@@ -188,6 +188,36 @@ static int __release_resource(struct res
return -EINVAL;
}
+static void __release_child_resources(struct resource *r)
+{
+ struct resource *tmp, *p;
+ resource_size_t size;
+
+ p = r->child;
+ r->child = NULL;
+ while (p) {
+ tmp = p;
+ p = p->sibling;
+
+ tmp->parent = NULL;
+ tmp->sibling = NULL;
+ __release_child_resources(tmp);
+
+ printk(KERN_DEBUG "release child resource %pR\n", tmp);
+ /* need to restore size, and keep flags */
+ size = resource_size(tmp);
+ tmp->start = 0;
+ tmp->end = size - 1;
+ }
+}
+
+void release_child_resources(struct resource *r)
+{
+ write_lock(&resource_lock);
+ __release_child_resources(r);
+ write_unlock(&resource_lock);
+}
+
/**
* request_resource - request and reserve an I/O or memory resource
* @root: root resource descriptor
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