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Message-ID: <20150729202440.GA9640@google.com>
Date: Wed, 29 Jul 2015 15:24:40 -0500
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Jiang Liu <jiang.liu@...ux.intel.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Marc Zyngier <marc.zyngier@....com>,
Hanjun Guo <hanjun.guo@...aro.org>,
Liviu Dudau <Liviu.Dudau@....com>,
Yijing Wang <wangyijing@...wei.com>,
Len Brown <lenb@...nel.org>, Lv Zheng <lv.zheng@...el.com>,
LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, "x86 @ kernel . org" <x86@...nel.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [Patch v5 4/6] PCI/ACPI: Consolidate common PCI host bridge code
into ACPI core
On Tue, Jun 09, 2015 at 12:20:46AM +0800, Jiang Liu wrote:
> Introduce common interface acpi_pci_root_create() and related data
> structures to create PCI root bus for ACPI PCI host bridges. It will
> be used to kill duplicated arch specific code for IA64 and x86. It may
> also help ARM64 in future.
I assume most of this code is copied from somewhere else. You should
mention where it came from.
> Tested-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
> drivers/acpi/pci_root.c | 198 ++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/pci-acpi.h | 23 ++++++
> 2 files changed, 221 insertions(+)
>
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 1b5569c092c6..70f851dc0051 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -656,6 +656,204 @@ static void acpi_pci_root_remove(struct acpi_device *device)
> kfree(root);
> }
>
> +static void acpi_pci_root_validate_resources(struct device *dev,
> + struct list_head *resources,
> + unsigned long type)
> +{
> + LIST_HEAD(list);
> + struct resource *res1, *res2, *root = NULL;
> + struct resource_entry *tmp, *entry, *entry2;
> +
> + BUG_ON((type & (IORESOURCE_MEM | IORESOURCE_IO)) == 0);
> + root = (type & IORESOURCE_MEM) ? &iomem_resource : &ioport_resource;
> +
> + list_splice_init(resources, &list);
> + resource_list_for_each_entry_safe(entry, tmp, &list) {
> + bool free = false;
> + resource_size_t end;
> +
> + res1 = entry->res;
> + if (!(res1->flags & type))
> + goto next;
> +
> + /* Exclude non-addressable range or non-addressable portion */
> + end = min(res1->end, root->end);
> + if (end <= res1->start) {
> + dev_info(dev, "host bridge window %pR (ignored, not CPU addressable)\n",
> + res1);
> + free = true;
> + goto next;
> + } else if (res1->end != end) {
> + dev_info(dev, "host bridge window %pR ([%#llx-%#llx] ignored, not CPU addressable)\n",
> + res1, (unsigned long long)end + 1,
> + (unsigned long long)res1->end);
> + res1->end = end;
> + }
> +
> + resource_list_for_each_entry(entry2, resources) {
> + res2 = entry2->res;
> + if (!(res2->flags & type))
> + continue;
> +
> + /*
> + * I don't like throwing away windows because then
> + * our resources no longer match the ACPI _CRS, but
> + * the kernel resource tree doesn't allow overlaps.
> + */
> + if (resource_overlaps(res1, res2)) {
> + res2->start = min(res1->start, res2->start);
> + res2->end = max(res1->end, res2->end);
> + dev_info(dev, "host bridge window expanded to %pR; %pR ignored\n",
> + res2, res1);
> + free = true;
> + goto next;
> + }
> + }
> +
> +next:
> + resource_list_del(entry);
> + if (free)
> + resource_list_free_entry(entry);
> + else
> + resource_list_add_tail(entry, resources);
> + }
> +}
> +
> +static int acpi_pci_probe_root_resources(struct acpi_pci_root_info *info)
> +{
> + int ret;
> + struct list_head *list = &info->resources;
> + struct acpi_device *device = info->bridge;
> + struct resource_entry *entry, *tmp;
> + unsigned long flags;
> +
> + flags = IORESOURCE_IO | IORESOURCE_MEM | IORESOURCE_MEM_8AND16BIT;
> + ret = acpi_dev_get_resources(device, list,
> + acpi_dev_filter_resource_type_cb,
> + (void *)flags);
> + if (ret < 0)
> + dev_warn(&device->dev,
> + "failed to parse _CRS method, error code %d\n", ret);
> + else if (ret == 0)
> + dev_dbg(&device->dev,
> + "no IO and memory resources present in _CRS\n");
> + else {
> + resource_list_for_each_entry_safe(entry, tmp, list) {
> + if (entry->res->flags & IORESOURCE_DISABLED)
> + resource_list_destroy_entry(entry);
> + else
> + entry->res->name = info->name;
> + }
> + acpi_pci_root_validate_resources(&device->dev, list,
> + IORESOURCE_MEM);
> + acpi_pci_root_validate_resources(&device->dev, list,
> + IORESOURCE_IO);
> + }
Please use this style to minimize indentation and return errors as soon as
possible:
if (ret < 0) {
dev_warn(...)
return ret;
}
if (ret == 0) {
dev_dbg(...);
return 0;
}
resource_list_for_each_entry_safe(...) {
}
return ret;
> + return ret;
> +}
> +
> +static void pci_acpi_root_add_resources(struct acpi_pci_root_info *info)
> +{
> + struct resource_entry *entry, *tmp;
> + struct resource *res, *conflict, *root = NULL;
> +
> + resource_list_for_each_entry_safe(entry, tmp, &info->resources) {
> + res = entry->res;
> + if (res->flags & IORESOURCE_MEM)
> + root = &iomem_resource;
> + else if (res->flags & IORESOURCE_IO)
> + root = &ioport_resource;
> + else
> + continue;
> +
> + conflict = insert_resource_conflict(root, res);
> + if (conflict) {
> + dev_info(&info->bridge->dev,
> + "ignoring host bridge window %pR (conflicts with %s %pR)\n",
> + res, conflict->name, conflict);
> + resource_list_destroy_entry(entry);
> + }
> + }
> +}
> +
> +static void __acpi_pci_root_release_info(struct acpi_pci_root_info *info)
> +{
> + struct resource *res;
> + struct resource_entry *entry, *tmp;
> +
> + if (!info)
> + return;
In what circumstance could "info" be NULL? As far as I can tell, the only
way it could be NULL is if we're called from acpi_pci_root_release_info()
and the bridge->release_data element got scribbled on after we called
pci_set_host_bridge_release(). In that case, I'd rather oops than silently
return.
> + resource_list_for_each_entry_safe(entry, tmp, &info->resources) {
> + res = entry->res;
> + if (res->parent &&
> + (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> + release_resource(res);
> + resource_list_destroy_entry(entry);
> + }
> +
> + info->ops->release_info(info);
> +}
> +
> +static void acpi_pci_root_release_info(struct pci_host_bridge *bridge)
> +{
> + struct resource *res;
> + struct resource_entry *entry;
> +
> + resource_list_for_each_entry(entry, &bridge->windows) {
> + res = entry->res;
> + if (res->parent &&
> + (res->flags & (IORESOURCE_MEM | IORESOURCE_IO)))
> + release_resource(res);
> + }
> + __acpi_pci_root_release_info(bridge->release_data);
> +}
> +
> +struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
> + struct acpi_pci_root_ops *ops,
> + struct acpi_pci_root_info *info,
> + void *sysdata, int segment, int node)
> +{
> + int ret, busnum = root->secondary.start;
> + struct acpi_device *device = root->device;
> + struct pci_bus *bus;
> +
> + info->root = root;
> + info->bridge = device;
> + info->ops = ops;
> + INIT_LIST_HEAD(&info->resources);
> + snprintf(info->name, sizeof(info->name), "PCI Bus %04x:%02x",
> + segment, busnum);
> +
> + if (ops->init_info && ops->init_info(info))
> + goto out_release_info;
> + ret = acpi_pci_probe_root_resources(info);
> + if (ops->prepare_resources)
> + ret = ops->prepare_resources(info, ret);
It's goofy to pass the return value from acpi_pci_probe_root_resources()
into prepare_resources(), especially since the local context gives no clue
about what "ret" means.
Neither the x86 nor the ia64 version of pci_acpi_root_prepare_resources()
actually does anything useful with "ret" except return it.
I think you should just make acpi_pci_probe_root_resources() void. It will
create a list of zero or more resources from _CRS. If _CRS fails, you
already print a diagnostic and the list will be empty. If _CRS succeeds
and there are no windows, you also print a (debug) diagnostic and the list
will be empty. The pci_acpi_root_prepare_resources() implementations will
deal with empty lists just fine.
I think the change from your code here is that we would create the root bus
and enumerate it even if _CRS fails. I think that's OK: we'll find devices
and we'll learn what resources they want, but we won't have anything to
assign them. I think that's OK and it will make this code simpler.
> + if (ret < 0)
> + goto out_release_info;
> + else if (ret > 0)
> + pci_acpi_root_add_resources(info);
> + pci_add_resource(&info->resources, &root->secondary);
> +
> + bus = pci_create_root_bus(NULL, busnum, ops->pci_ops,
> + sysdata, &info->resources);
> + if (bus) {
if (!bus)
goto out_release_info;
Then this code can be un-indented:
> + pci_scan_child_bus(bus);
> + pci_set_host_bridge_release(to_pci_host_bridge(bus->bridge),
> + acpi_pci_root_release_info, info);
> + if (node != NUMA_NO_NODE)
> + dev_printk(KERN_DEBUG, &bus->dev, "on NUMA node %d\n",
> + node);
> + return bus;
> + }
> +
> +out_release_info:
> + __acpi_pci_root_release_info(info);
> + return NULL;
> +}
> +
> void __init acpi_pci_root_init(void)
> {
> acpi_hest_init();
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index a965efa52152..a76cb6f24ca1 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -52,6 +52,29 @@ static inline acpi_handle acpi_pci_get_bridge_handle(struct pci_bus *pbus)
> return ACPI_HANDLE(dev);
> }
>
> +struct acpi_pci_root;
> +struct acpi_pci_root_ops;
> +
> +struct acpi_pci_root_info {
> + struct acpi_pci_root *root;
> + struct acpi_device *bridge;
> + struct acpi_pci_root_ops *ops;
> + struct list_head resources;
> + char name[16];
> +};
> +
> +struct acpi_pci_root_ops {
> + struct pci_ops *pci_ops;
> + int (*init_info)(struct acpi_pci_root_info *info);
> + void (*release_info)(struct acpi_pci_root_info *info);
> + int (*prepare_resources)(struct acpi_pci_root_info *info, int status);
> +};
> +
> +extern struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
> + struct acpi_pci_root_ops *ops,
> + struct acpi_pci_root_info *info,
> + void *sd, int seg, int node);
Drop the "extern" here to match the declarations below. I know there's
still a mix in this file, but my preference is to skip them in new code.
> void acpi_pci_add_bus(struct pci_bus *bus);
> void acpi_pci_remove_bus(struct pci_bus *bus);
>
> --
> 1.7.10.4
>
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