Patchwork [01/15] PCI, acpiphp: Separate out hot-add support of pci host bridge

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Submitter Myron Stowe
Date Dec. 7, 2012, 6:25 a.m.
Message ID <20121207062500.11051.44198.stgit@amt.stowe>
Download mbox | patch
Permalink /patch/204406/
State Changes Requested
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Comments

Myron Stowe - Dec. 7, 2012, 6:25 a.m.
From: Yinghai Lu <yinghai@kernel.org>

It causes confusion.

We may only need acpi hp for pci host bridge.

Split host bridge hot-add support to pci_root_hp, and keep acpiphp simple.

-v2: put back pci_root_hp change in one patch
-v3: add pcibios_resource_survey_bus() calling
-v4: remove not needed code with remove_bridge
-v5: put back support for acpiphp support for slots just on root bus.
-v6: change some functions to *_p2p_* to make it more clean.
-v7: split hot_added change out.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
---

 drivers/acpi/Makefile              |    1 
 drivers/acpi/pci_root_hp.c         |  228 ++++++++++++++++++++++++++++++++++++
 drivers/pci/hotplug/acpiphp_glue.c |   59 ++-------
 3 files changed, 244 insertions(+), 44 deletions(-)
 create mode 100644 drivers/acpi/pci_root_hp.c


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Bjorn Helgaas - Dec. 7, 2012, 7:32 p.m.
On Thu, Dec 6, 2012 at 11:25 PM, Myron Stowe <myron.stowe@redhat.com> wrote:
> From: Yinghai Lu <yinghai@kernel.org>
>
> It causes confusion.

I completely agree that acpiphp causes confusion  :)

> We may only need acpi hp for pci host bridge.
>
> Split host bridge hot-add support to pci_root_hp, and keep acpiphp simple.
>
> -v2: put back pci_root_hp change in one patch
> -v3: add pcibios_resource_survey_bus() calling
> -v4: remove not needed code with remove_bridge
> -v5: put back support for acpiphp support for slots just on root bus.
> -v6: change some functions to *_p2p_* to make it more clean.
> -v7: split hot_added change out.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
> ---
>
>  drivers/acpi/Makefile              |    1
>  drivers/acpi/pci_root_hp.c         |  228 ++++++++++++++++++++++++++++++++++++
>  drivers/pci/hotplug/acpiphp_glue.c |   59 ++-------
>  3 files changed, 244 insertions(+), 44 deletions(-)
>  create mode 100644 drivers/acpi/pci_root_hp.c
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 82422fe..4edfe41 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -36,6 +36,7 @@ acpi-y                                += processor_core.o
>  acpi-y                         += ec.o
>  acpi-$(CONFIG_ACPI_DOCK)       += dock.o
>  acpi-y                         += pci_root.o pci_link.o pci_irq.o pci_bind.o
> +acpi-$(CONFIG_HOTPLUG)         += pci_root_hp.o

I absolutely, 110% agree with splitting out the host bridge hotplug
code from the PCI device hotplug code.

But I don't want to put this in a separate file; I think it should go
directly in pci_root.c.  Putting it in a separate file gives the
illusion that hotplug is something we only do in unusual
circumstances.  But that's wrong -- even at boot-time we should be
using the same hot-plug flow as we do later.

Plus, I want people to be forced to look at the ugliness of this code
every time they look at pci_root.c.  Maybe that will help get it
cleaned up eventually.

For example, as soon as you put this code in pci_root.c instead of
pci_root_hp.c, it becomes obvious that we're keeping a list of host
bridges in both places, and we probably don't need two lists.  And it
seems dubious that acpi_pci_root_hp_init() is an initcall that walks
the namespace looking for host bridges, when acpi_pci_root_add()
already exists and is called for every host bridge.

Bjorn

>  acpi-y                         += power.o
>  acpi-y                         += event.o
>  acpi-y                         += sysfs.o
> diff --git a/drivers/acpi/pci_root_hp.c b/drivers/acpi/pci_root_hp.c
> new file mode 100644
> index 0000000..10c12aa
> --- /dev/null
> +++ b/drivers/acpi/pci_root_hp.c
> @@ -0,0 +1,228 @@
> +/*
> + * Separated from drivers/pci/hotplug/acpiphp_glue.c
> + *     only support root bridge
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +
> +static LIST_HEAD(acpi_root_bridge_list);
> +struct acpi_root_bridge {
> +       struct list_head list;
> +       acpi_handle handle;
> +       u32 flags;
> +};
> +
> +/* bridge flags */
> +#define ROOT_BRIDGE_HAS_EJ0    (0x00000002)
> +#define ROOT_BRIDGE_HAS_PS3    (0x00000080)
> +
> +#define ACPI_STA_FUNCTIONING   (0x00000008)
> +
> +static struct acpi_root_bridge *acpi_root_handle_to_bridge(acpi_handle handle)
> +{
> +       struct acpi_root_bridge *bridge;
> +
> +       list_for_each_entry(bridge, &acpi_root_bridge_list, list)
> +               if (bridge->handle == handle)
> +                       return bridge;
> +
> +       return NULL;
> +}
> +
> +/* allocate and initialize host bridge data structure */
> +static void add_acpi_root_bridge(acpi_handle handle)
> +{
> +       struct acpi_root_bridge *bridge;
> +       acpi_handle dummy_handle;
> +       acpi_status status;
> +
> +       /* if the bridge doesn't have _STA, we assume it is always there */
> +       status = acpi_get_handle(handle, "_STA", &dummy_handle);
> +       if (ACPI_SUCCESS(status)) {
> +               unsigned long long tmp;
> +
> +               status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
> +               if (ACPI_FAILURE(status)) {
> +                       printk(KERN_DEBUG "%s: _STA evaluation failure\n",
> +                                                __func__);
> +                       return;
> +               }
> +               if ((tmp & ACPI_STA_FUNCTIONING) == 0)
> +                       /* don't register this object */
> +                       return;
> +       }
> +
> +       bridge = kzalloc(sizeof(struct acpi_root_bridge), GFP_KERNEL);
> +       if (!bridge)
> +               return;
> +
> +       bridge->handle = handle;
> +
> +       if (ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0", &dummy_handle)))
> +               bridge->flags |= ROOT_BRIDGE_HAS_EJ0;
> +       if (ACPI_SUCCESS(acpi_get_handle(handle, "_PS3", &dummy_handle)))
> +               bridge->flags |= ROOT_BRIDGE_HAS_PS3;
> +
> +       list_add(&bridge->list, &acpi_root_bridge_list);
> +}
> +
> +struct acpi_root_hp_work {
> +       struct work_struct work;
> +       acpi_handle handle;
> +       u32 type;
> +       void *context;
> +};
> +
> +static void alloc_acpi_root_hp_work(acpi_handle handle, u32 type,
> +                                       void *context,
> +                                       void (*func)(struct work_struct *work))
> +{
> +       struct acpi_root_hp_work *hp_work;
> +       int ret;
> +
> +       hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
> +       if (!hp_work)
> +               return;
> +
> +       hp_work->handle = handle;
> +       hp_work->type = type;
> +       hp_work->context = context;
> +
> +       INIT_WORK(&hp_work->work, func);
> +       ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
> +       if (!ret)
> +               kfree(hp_work);
> +}
> +
> +static void handle_root_bridge_insertion(acpi_handle handle)
> +{
> +       struct acpi_device *device, *pdevice;
> +       acpi_handle phandle;
> +       int ret_val;
> +
> +       acpi_get_parent(handle, &phandle);
> +       if (acpi_bus_get_device(phandle, &pdevice)) {
> +               printk(KERN_DEBUG "no parent device, assuming NULL\n");
> +               pdevice = NULL;
> +       }
> +       if (!acpi_bus_get_device(handle, &device)) {
> +               /* check if  pci root_bus is removed */
> +               struct acpi_pci_root *root = acpi_driver_data(device);
> +               if (pci_find_bus(root->segment, root->secondary.start))
> +                       return;
> +
> +               printk(KERN_DEBUG "bus exists... trim\n");
> +               /* this shouldn't be in here, so remove
> +                * the bus then re-add it...
> +                */
> +               ret_val = acpi_bus_trim(device, 1);
> +               printk(KERN_DEBUG "acpi_bus_trim return %x\n", ret_val);
> +       }
> +       if (acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE)) {
> +               printk(KERN_ERR "cannot add bridge to acpi list\n");
> +               return;
> +       }
> +       if (acpi_bus_start(device))
> +               printk(KERN_ERR "cannot start bridge\n");
> +}
> +
> +static void _handle_hotplug_event_root(struct work_struct *work)
> +{
> +       struct acpi_root_bridge *bridge;
> +       char objname[64];
> +       struct acpi_buffer buffer = { .length = sizeof(objname),
> +                                     .pointer = objname };
> +       struct acpi_root_hp_work *hp_work;
> +       acpi_handle handle;
> +       u32 type;
> +
> +       hp_work = container_of(work, struct acpi_root_hp_work, work);
> +       handle = hp_work->handle;
> +       type = hp_work->type;
> +
> +       bridge = acpi_root_handle_to_bridge(handle);
> +
> +       acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> +
> +       switch (type) {
> +       case ACPI_NOTIFY_BUS_CHECK:
> +               /* bus enumerate */
> +               printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
> +                                objname);
> +               if (!bridge) {
> +                       handle_root_bridge_insertion(handle);
> +                       add_acpi_root_bridge(handle);
> +               }
> +
> +               break;
> +
> +       case ACPI_NOTIFY_DEVICE_CHECK:
> +               /* device check */
> +               printk(KERN_DEBUG "%s: Device check notify on %s\n", __func__,
> +                                objname);
> +               if (!bridge) {
> +                       handle_root_bridge_insertion(handle);
> +                       add_acpi_root_bridge(handle);
> +               }
> +               break;
> +
> +       default:
> +               printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
> +                                type, objname);
> +               break;
> +       }
> +
> +       kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
> +}
> +
> +static void handle_hotplug_event_root(acpi_handle handle, u32 type,
> +                                       void *context)
> +{
> +       alloc_acpi_root_hp_work(handle, type, context,
> +                               _handle_hotplug_event_root);
> +}
> +
> +static acpi_status __init
> +find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
> +{
> +       char objname[64];
> +       struct acpi_buffer buffer = { .length = sizeof(objname),
> +                                     .pointer = objname };
> +       int *count = (int *)context;
> +
> +       if (!acpi_is_root_bridge(handle))
> +               return AE_OK;
> +
> +       (*count)++;
> +
> +       acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
> +
> +       acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> +                               handle_hotplug_event_root, NULL);
> +       printk(KERN_DEBUG "acpi root: %s notify handler installed\n", objname);
> +
> +       add_acpi_root_bridge(handle);
> +
> +       return AE_OK;
> +}
> +
> +static int __init acpi_pci_root_hp_init(void)
> +{
> +       int num = 0;
> +
> +       acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> +               ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
> +
> +       printk(KERN_DEBUG "Found %d acpi root devices\n", num);
> +
> +       return 0;
> +}
> +
> +subsys_initcall(acpi_pci_root_hp_init);
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index 3d6d4fd..d0369dc 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -543,10 +543,13 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>         acpi_status status;
>         acpi_handle handle = bridge->handle;
>
> -       status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> +       if (bridge->type != BRIDGE_TYPE_HOST) {
> +               status = acpi_remove_notify_handler(handle,
> +                                           ACPI_SYSTEM_NOTIFY,
>                                             handle_hotplug_event_bridge);
> -       if (ACPI_FAILURE(status))
> -               err("failed to remove notify handler\n");
> +               if (ACPI_FAILURE(status))
> +                       err("failed to remove notify handler\n");
> +       }
>
>         if ((bridge->type != BRIDGE_TYPE_HOST) &&
>             ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)) {
> @@ -630,9 +633,6 @@ static void remove_bridge(struct acpi_pci_root *root)
>         bridge = acpiphp_handle_to_bridge(handle);
>         if (bridge)
>                 cleanup_bridge(bridge);
> -       else
> -               acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> -                                          handle_hotplug_event_bridge);
>  }
>
>  static int power_on_slot(struct acpiphp_slot *slot)
> @@ -1107,18 +1107,12 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
>  }
>
>  /* Program resources in newly inserted bridge */
> -static int acpiphp_configure_bridge (acpi_handle handle)
> +static int acpiphp_configure_p2p_bridge(acpi_handle handle)
>  {
> -       struct pci_bus *bus;
> +       struct pci_dev *pdev = acpi_get_pci_dev(handle);
> +       struct pci_bus *bus = pdev->subordinate;
>
> -       if (acpi_is_root_bridge(handle)) {
> -               struct acpi_pci_root *root = acpi_pci_find_root(handle);
> -               bus = root->bus;
> -       } else {
> -               struct pci_dev *pdev = acpi_get_pci_dev(handle);
> -               bus = pdev->subordinate;
> -               pci_dev_put(pdev);
> -       }
> +       pci_dev_put(pdev);
>
>         pci_bus_size_bridges(bus);
>         pci_bus_assign_resources(bus);
> @@ -1128,7 +1122,7 @@ static int acpiphp_configure_bridge (acpi_handle handle)
>         return 0;
>  }
>
> -static void handle_bridge_insertion(acpi_handle handle, u32 type)
> +static void handle_p2p_bridge_insertion(acpi_handle handle, u32 type)
>  {
>         struct acpi_device *device, *pdevice;
>         acpi_handle phandle;
> @@ -1148,9 +1142,9 @@ static void handle_bridge_insertion(acpi_handle handle, u32 type)
>                 err("cannot add bridge to acpi list\n");
>                 return;
>         }
> -       if (!acpiphp_configure_bridge(handle) &&
> +       if (!acpiphp_configure_p2p_bridge(handle) &&
>                 !acpi_bus_start(device))
> -               add_bridge(handle);
> +               add_p2p_bridge(handle);
>         else
>                 err("cannot configure and start bridge\n");
>
> @@ -1236,7 +1230,7 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
>
>         if (acpi_bus_get_device(handle, &device)) {
>                 /* This bridge must have just been physically inserted */
> -               handle_bridge_insertion(handle, type);
> +               handle_p2p_bridge_insertion(handle, type);
>                 goto out;
>         }
>
> @@ -1413,21 +1407,6 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
>                               _handle_hotplug_event_func);
>  }
>
> -static acpi_status
> -find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
> -{
> -       int *count = (int *)context;
> -
> -       if (!acpi_is_root_bridge(handle))
> -               return AE_OK;
> -
> -       (*count)++;
> -       acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> -                                   handle_hotplug_event_bridge, NULL);
> -
> -       return AE_OK ;
> -}
> -
>  static struct acpi_pci_driver acpi_pci_hp_driver = {
>         .add =          add_bridge,
>         .remove =       remove_bridge,
> @@ -1438,15 +1417,7 @@ static struct acpi_pci_driver acpi_pci_hp_driver = {
>   */
>  int __init acpiphp_glue_init(void)
>  {
> -       int num = 0;
> -
> -       acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> -                       ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
> -
> -       if (num <= 0)
> -               return -1;
> -       else
> -               acpi_pci_register_driver(&acpi_pci_hp_driver);
> +       acpi_pci_register_driver(&acpi_pci_hp_driver);
>
>         return 0;
>  }
>
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Rafael J. Wysocki - Dec. 7, 2012, 9:04 p.m.
On Friday, December 07, 2012 12:32:46 PM Bjorn Helgaas wrote:
> On Thu, Dec 6, 2012 at 11:25 PM, Myron Stowe <myron.stowe@redhat.com> wrote:
> > From: Yinghai Lu <yinghai@kernel.org>
> >
> > It causes confusion.
> 
> I completely agree that acpiphp causes confusion  :)
> 
> > We may only need acpi hp for pci host bridge.
> >
> > Split host bridge hot-add support to pci_root_hp, and keep acpiphp simple.
> >
> > -v2: put back pci_root_hp change in one patch
> > -v3: add pcibios_resource_survey_bus() calling
> > -v4: remove not needed code with remove_bridge
> > -v5: put back support for acpiphp support for slots just on root bus.
> > -v6: change some functions to *_p2p_* to make it more clean.
> > -v7: split hot_added change out.
> >
> > Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> > Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
> > ---
> >
> >  drivers/acpi/Makefile              |    1
> >  drivers/acpi/pci_root_hp.c         |  228 ++++++++++++++++++++++++++++++++++++
> >  drivers/pci/hotplug/acpiphp_glue.c |   59 ++-------
> >  3 files changed, 244 insertions(+), 44 deletions(-)
> >  create mode 100644 drivers/acpi/pci_root_hp.c
> >
> > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > index 82422fe..4edfe41 100644
> > --- a/drivers/acpi/Makefile
> > +++ b/drivers/acpi/Makefile
> > @@ -36,6 +36,7 @@ acpi-y                                += processor_core.o
> >  acpi-y                         += ec.o
> >  acpi-$(CONFIG_ACPI_DOCK)       += dock.o
> >  acpi-y                         += pci_root.o pci_link.o pci_irq.o pci_bind.o
> > +acpi-$(CONFIG_HOTPLUG)         += pci_root_hp.o
> 
> I absolutely, 110% agree with splitting out the host bridge hotplug
> code from the PCI device hotplug code.
> 
> But I don't want to put this in a separate file; I think it should go
> directly in pci_root.c.  Putting it in a separate file gives the
> illusion that hotplug is something we only do in unusual
> circumstances.  But that's wrong -- even at boot-time we should be
> using the same hot-plug flow as we do later.
> 
> Plus, I want people to be forced to look at the ugliness of this code
> every time they look at pci_root.c.  Maybe that will help get it
> cleaned up eventually.
> 
> For example, as soon as you put this code in pci_root.c instead of
> pci_root_hp.c, it becomes obvious that we're keeping a list of host
> bridges in both places, and we probably don't need two lists.  And it
> seems dubious that acpi_pci_root_hp_init() is an initcall that walks
> the namespace looking for host bridges, when acpi_pci_root_add()
> already exists and is called for every host bridge.

Agreed.

Thanks,
Rafael
Yinghai Lu - Dec. 7, 2012, 9:30 p.m.
On Fri, Dec 7, 2012 at 11:32 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Thu, Dec 6, 2012 at 11:25 PM, Myron Stowe <myron.stowe@redhat.com> wrote:
>> From: Yinghai Lu <yinghai@kernel.org>
>>
>>
> For example, as soon as you put this code in pci_root.c instead of
> pci_root_hp.c, it becomes obvious that we're keeping a list of host
> bridges in both places, and we probably don't need two lists.  And it
> seems dubious that acpi_pci_root_hp_init() is an initcall that walks
> the namespace looking for host bridges, when acpi_pci_root_add()
> already exists and is called for every host bridge.

removed the duplicated interface in following patch.

http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=shortlog;h=refs/heads/for-pci-split-pci-root-hp-2

http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=commitdiff;h=a1d1ef3f5e4932bc672d96dedd11c5d58f7f20f5

| [PATCH] PCI, ACPI: remove acpi_root_bridge in pci_root_hp
|
| Tang noticed that hotplug through container will not update acpi_root_bridge
| list.
|
| After closely checking, we don't need that for struct for tracking and
| could use acpi_pci_root directly.
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Bjorn Helgaas - Dec. 7, 2012, 9:36 p.m.
On Fri, Dec 7, 2012 at 2:30 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Fri, Dec 7, 2012 at 11:32 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>> On Thu, Dec 6, 2012 at 11:25 PM, Myron Stowe <myron.stowe@redhat.com> wrote:
>>> From: Yinghai Lu <yinghai@kernel.org>
>>>
>>>
>> For example, as soon as you put this code in pci_root.c instead of
>> pci_root_hp.c, it becomes obvious that we're keeping a list of host
>> bridges in both places, and we probably don't need two lists.  And it
>> seems dubious that acpi_pci_root_hp_init() is an initcall that walks
>> the namespace looking for host bridges, when acpi_pci_root_add()
>> already exists and is called for every host bridge.
>
> removed the duplicated interface in following patch.
>
> http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=shortlog;h=refs/heads/for-pci-split-pci-root-hp-2
>
> http://git.kernel.org/?p=linux/kernel/git/yinghai/linux-yinghai.git;a=commitdiff;h=a1d1ef3f5e4932bc672d96dedd11c5d58f7f20f5
>
> | [PATCH] PCI, ACPI: remove acpi_root_bridge in pci_root_hp
> |
> | Tang noticed that hotplug through container will not update acpi_root_bridge
> | list.
> |
> | After closely checking, we don't need that for struct for tracking and
> | could use acpi_pci_root directly.

Sorry I missed that; I had only looked at a few patches adjacent to
the one that split out this code.

I still would like the code to be all in pci_root.c.
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Yinghai Lu - Dec. 7, 2012, 9:42 p.m.
On Fri, Dec 7, 2012 at 1:36 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> On Fri, Dec 7, 2012 at 2:30 PM, Yinghai Lu <yinghai@kernel.org> wrote:
>
> Sorry I missed that; I had only looked at a few patches adjacent to
> the one that split out this code.
>
> I still would like the code to be all in pci_root.c.

ok, I will rebase that to put them in pci_root.c
and send them out after you take

[PATCH 0/8] PCI, ACPI, x86: Reserve fw allocated resource for hot-add root bus

Yinghai
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Patch

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 82422fe..4edfe41 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -36,6 +36,7 @@  acpi-y				+= processor_core.o
 acpi-y				+= ec.o
 acpi-$(CONFIG_ACPI_DOCK)	+= dock.o
 acpi-y				+= pci_root.o pci_link.o pci_irq.o pci_bind.o
+acpi-$(CONFIG_HOTPLUG)		+= pci_root_hp.o
 acpi-y				+= power.o
 acpi-y				+= event.o
 acpi-y				+= sysfs.o
diff --git a/drivers/acpi/pci_root_hp.c b/drivers/acpi/pci_root_hp.c
new file mode 100644
index 0000000..10c12aa
--- /dev/null
+++ b/drivers/acpi/pci_root_hp.c
@@ -0,0 +1,228 @@ 
+/*
+ * Separated from drivers/pci/hotplug/acpiphp_glue.c
+ *	only support root bridge
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+
+static LIST_HEAD(acpi_root_bridge_list);
+struct acpi_root_bridge {
+	struct list_head list;
+	acpi_handle handle;
+	u32 flags;
+};
+
+/* bridge flags */
+#define ROOT_BRIDGE_HAS_EJ0	(0x00000002)
+#define ROOT_BRIDGE_HAS_PS3	(0x00000080)
+
+#define ACPI_STA_FUNCTIONING	(0x00000008)
+
+static struct acpi_root_bridge *acpi_root_handle_to_bridge(acpi_handle handle)
+{
+	struct acpi_root_bridge *bridge;
+
+	list_for_each_entry(bridge, &acpi_root_bridge_list, list)
+		if (bridge->handle == handle)
+			return bridge;
+
+	return NULL;
+}
+
+/* allocate and initialize host bridge data structure */
+static void add_acpi_root_bridge(acpi_handle handle)
+{
+	struct acpi_root_bridge *bridge;
+	acpi_handle dummy_handle;
+	acpi_status status;
+
+	/* if the bridge doesn't have _STA, we assume it is always there */
+	status = acpi_get_handle(handle, "_STA", &dummy_handle);
+	if (ACPI_SUCCESS(status)) {
+		unsigned long long tmp;
+
+		status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
+		if (ACPI_FAILURE(status)) {
+			printk(KERN_DEBUG "%s: _STA evaluation failure\n",
+						 __func__);
+			return;
+		}
+		if ((tmp & ACPI_STA_FUNCTIONING) == 0)
+			/* don't register this object */
+			return;
+	}
+
+	bridge = kzalloc(sizeof(struct acpi_root_bridge), GFP_KERNEL);
+	if (!bridge)
+		return;
+
+	bridge->handle = handle;
+
+	if (ACPI_SUCCESS(acpi_get_handle(handle, "_EJ0", &dummy_handle)))
+		bridge->flags |= ROOT_BRIDGE_HAS_EJ0;
+	if (ACPI_SUCCESS(acpi_get_handle(handle, "_PS3", &dummy_handle)))
+		bridge->flags |= ROOT_BRIDGE_HAS_PS3;
+
+	list_add(&bridge->list, &acpi_root_bridge_list);
+}
+
+struct acpi_root_hp_work {
+	struct work_struct work;
+	acpi_handle handle;
+	u32 type;
+	void *context;
+};
+
+static void alloc_acpi_root_hp_work(acpi_handle handle, u32 type,
+					void *context,
+					void (*func)(struct work_struct *work))
+{
+	struct acpi_root_hp_work *hp_work;
+	int ret;
+
+	hp_work = kmalloc(sizeof(*hp_work), GFP_KERNEL);
+	if (!hp_work)
+		return;
+
+	hp_work->handle = handle;
+	hp_work->type = type;
+	hp_work->context = context;
+
+	INIT_WORK(&hp_work->work, func);
+	ret = queue_work(kacpi_hotplug_wq, &hp_work->work);
+	if (!ret)
+		kfree(hp_work);
+}
+
+static void handle_root_bridge_insertion(acpi_handle handle)
+{
+	struct acpi_device *device, *pdevice;
+	acpi_handle phandle;
+	int ret_val;
+
+	acpi_get_parent(handle, &phandle);
+	if (acpi_bus_get_device(phandle, &pdevice)) {
+		printk(KERN_DEBUG "no parent device, assuming NULL\n");
+		pdevice = NULL;
+	}
+	if (!acpi_bus_get_device(handle, &device)) {
+		/* check if  pci root_bus is removed */
+		struct acpi_pci_root *root = acpi_driver_data(device);
+		if (pci_find_bus(root->segment, root->secondary.start))
+			return;
+
+		printk(KERN_DEBUG "bus exists... trim\n");
+		/* this shouldn't be in here, so remove
+		 * the bus then re-add it...
+		 */
+		ret_val = acpi_bus_trim(device, 1);
+		printk(KERN_DEBUG "acpi_bus_trim return %x\n", ret_val);
+	}
+	if (acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE)) {
+		printk(KERN_ERR "cannot add bridge to acpi list\n");
+		return;
+	}
+	if (acpi_bus_start(device))
+		printk(KERN_ERR "cannot start bridge\n");
+}
+
+static void _handle_hotplug_event_root(struct work_struct *work)
+{
+	struct acpi_root_bridge *bridge;
+	char objname[64];
+	struct acpi_buffer buffer = { .length = sizeof(objname),
+				      .pointer = objname };
+	struct acpi_root_hp_work *hp_work;
+	acpi_handle handle;
+	u32 type;
+
+	hp_work = container_of(work, struct acpi_root_hp_work, work);
+	handle = hp_work->handle;
+	type = hp_work->type;
+
+	bridge = acpi_root_handle_to_bridge(handle);
+
+	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+
+	switch (type) {
+	case ACPI_NOTIFY_BUS_CHECK:
+		/* bus enumerate */
+		printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
+				 objname);
+		if (!bridge) {
+			handle_root_bridge_insertion(handle);
+			add_acpi_root_bridge(handle);
+		}
+
+		break;
+
+	case ACPI_NOTIFY_DEVICE_CHECK:
+		/* device check */
+		printk(KERN_DEBUG "%s: Device check notify on %s\n", __func__,
+				 objname);
+		if (!bridge) {
+			handle_root_bridge_insertion(handle);
+			add_acpi_root_bridge(handle);
+		}
+		break;
+
+	default:
+		printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
+				 type, objname);
+		break;
+	}
+
+	kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
+}
+
+static void handle_hotplug_event_root(acpi_handle handle, u32 type,
+					void *context)
+{
+	alloc_acpi_root_hp_work(handle, type, context,
+				_handle_hotplug_event_root);
+}
+
+static acpi_status __init
+find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+	char objname[64];
+	struct acpi_buffer buffer = { .length = sizeof(objname),
+				      .pointer = objname };
+	int *count = (int *)context;
+
+	if (!acpi_is_root_bridge(handle))
+		return AE_OK;
+
+	(*count)++;
+
+	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+
+	acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
+				handle_hotplug_event_root, NULL);
+	printk(KERN_DEBUG "acpi root: %s notify handler installed\n", objname);
+
+	add_acpi_root_bridge(handle);
+
+	return AE_OK;
+}
+
+static int __init acpi_pci_root_hp_init(void)
+{
+	int num = 0;
+
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+		ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
+
+	printk(KERN_DEBUG "Found %d acpi root devices\n", num);
+
+	return 0;
+}
+
+subsys_initcall(acpi_pci_root_hp_init);
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 3d6d4fd..d0369dc 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -543,10 +543,13 @@  static void cleanup_bridge(struct acpiphp_bridge *bridge)
 	acpi_status status;
 	acpi_handle handle = bridge->handle;
 
-	status = acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
+	if (bridge->type != BRIDGE_TYPE_HOST) {
+		status = acpi_remove_notify_handler(handle,
+					    ACPI_SYSTEM_NOTIFY,
 					    handle_hotplug_event_bridge);
-	if (ACPI_FAILURE(status))
-		err("failed to remove notify handler\n");
+		if (ACPI_FAILURE(status))
+			err("failed to remove notify handler\n");
+	}
 
 	if ((bridge->type != BRIDGE_TYPE_HOST) &&
 	    ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)) {
@@ -630,9 +633,6 @@  static void remove_bridge(struct acpi_pci_root *root)
 	bridge = acpiphp_handle_to_bridge(handle);
 	if (bridge)
 		cleanup_bridge(bridge);
-	else
-		acpi_remove_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
-					   handle_hotplug_event_bridge);
 }
 
 static int power_on_slot(struct acpiphp_slot *slot)
@@ -1107,18 +1107,12 @@  static void acpiphp_sanitize_bus(struct pci_bus *bus)
 }
 
 /* Program resources in newly inserted bridge */
-static int acpiphp_configure_bridge (acpi_handle handle)
+static int acpiphp_configure_p2p_bridge(acpi_handle handle)
 {
-	struct pci_bus *bus;
+	struct pci_dev *pdev = acpi_get_pci_dev(handle);
+	struct pci_bus *bus = pdev->subordinate;
 
-	if (acpi_is_root_bridge(handle)) {
-		struct acpi_pci_root *root = acpi_pci_find_root(handle);
-		bus = root->bus;
-	} else {
-		struct pci_dev *pdev = acpi_get_pci_dev(handle);
-		bus = pdev->subordinate;
-		pci_dev_put(pdev);
-	}
+	pci_dev_put(pdev);
 
 	pci_bus_size_bridges(bus);
 	pci_bus_assign_resources(bus);
@@ -1128,7 +1122,7 @@  static int acpiphp_configure_bridge (acpi_handle handle)
 	return 0;
 }
 
-static void handle_bridge_insertion(acpi_handle handle, u32 type)
+static void handle_p2p_bridge_insertion(acpi_handle handle, u32 type)
 {
 	struct acpi_device *device, *pdevice;
 	acpi_handle phandle;
@@ -1148,9 +1142,9 @@  static void handle_bridge_insertion(acpi_handle handle, u32 type)
 		err("cannot add bridge to acpi list\n");
 		return;
 	}
-	if (!acpiphp_configure_bridge(handle) &&
+	if (!acpiphp_configure_p2p_bridge(handle) &&
 		!acpi_bus_start(device))
-		add_bridge(handle);
+		add_p2p_bridge(handle);
 	else
 		err("cannot configure and start bridge\n");
 
@@ -1236,7 +1230,7 @@  static void _handle_hotplug_event_bridge(struct work_struct *work)
 
 	if (acpi_bus_get_device(handle, &device)) {
 		/* This bridge must have just been physically inserted */
-		handle_bridge_insertion(handle, type);
+		handle_p2p_bridge_insertion(handle, type);
 		goto out;
 	}
 
@@ -1413,21 +1407,6 @@  static void handle_hotplug_event_func(acpi_handle handle, u32 type,
 			      _handle_hotplug_event_func);
 }
 
-static acpi_status
-find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
-{
-	int *count = (int *)context;
-
-	if (!acpi_is_root_bridge(handle))
-		return AE_OK;
-
-	(*count)++;
-	acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
-				    handle_hotplug_event_bridge, NULL);
-
-	return AE_OK ;
-}
-
 static struct acpi_pci_driver acpi_pci_hp_driver = {
 	.add =		add_bridge,
 	.remove =	remove_bridge,
@@ -1438,15 +1417,7 @@  static struct acpi_pci_driver acpi_pci_hp_driver = {
  */
 int __init acpiphp_glue_init(void)
 {
-	int num = 0;
-
-	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
-			ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
-
-	if (num <= 0)
-		return -1;
-	else
-		acpi_pci_register_driver(&acpi_pci_hp_driver);
+	acpi_pci_register_driver(&acpi_pci_hp_driver);
 
 	return 0;
 }