[PATCH V2 0/3] ioapic hot-removal bugs

[PATCH V2 0/3] ioapic hot-removal bugs

[Rui Wang]

Hi Thomas,

Here's the v2 patchset according to your suggestion.

While testing ioapic hotplug, two bugs were found.

1) acpi_ioapic_add() is only called during hotadd of ioapics. Those
already present during system boot are not added, and thus cannot be
hot-removed.

2) ioapics[i].iomem_res were assigned the wrong pointers, causing panic
while hot-removing ioapics.

On a 4-socket brickland, hot-removal of the 3 sockets can be done
only after applying the first two patches. The 3rd patch is optional.

Regards,
Rui

v2: split the second patch into a one liner and a cleanup patch according
to Thomas.

Rui Wang (3):
  x86/ioapic: Support hot-removal of IOAPICs present during boot
  x86/ioapic: Fix wrong pointers in ioapic_setup_resources()
  x86/ioapic: Simplify ioapic_setup_resources()

 arch/x86/kernel/apic/io_apic.c | 18 +++++++-----------
 drivers/acpi/internal.h        |  2 --
 drivers/acpi/ioapic.c          |  7 ++++---
 drivers/acpi/pci_root.c        |  2 +-
 drivers/pci/setup-bus.c        |  5 ++++-
 include/linux/acpi.h           |  3 +++
 6 files changed, 19 insertions(+), 18 deletions(-)

-- 
1.8.3.1

[PATCH V2 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

IOAPICs present during system boot aren't added to ioapic_list,
thus are unable to be hot-removed. Fix it by calling
acpi_ioapic_add() during root bus enumeration.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 drivers/acpi/internal.h | 2 --
 drivers/acpi/ioapic.c   | 7 ++++---
 drivers/acpi/pci_root.c | 2 +-
 drivers/pci/setup-bus.c | 5 ++++-
 include/linux/acpi.h    | 3 +++
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 9bb0773..bb567a7 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
 void acpi_container_init(void);
 void acpi_memory_hotplug_init(void);
 #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
-int acpi_ioapic_add(struct acpi_pci_root *root);
 int acpi_ioapic_remove(struct acpi_pci_root *root);
 #else
-static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
 static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
 #endif
 #ifdef CONFIG_ACPI_DOCK
diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db..0f272e2 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -189,16 +189,17 @@ exit:
 	return AE_OK;
 }
 
-int acpi_ioapic_add(struct acpi_pci_root *root)
+int acpi_ioapic_add(acpi_handle root_handle)
 {
 	acpi_status status, retval = AE_OK;
 
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
 				     UINT_MAX, handle_ioapic_add, NULL,
-				     root->device->handle, (void **)&retval);
+				     root_handle, (void **)&retval);
 
 	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
 }
+EXPORT_SYMBOL_GPL(acpi_ioapic_add);
 
 int acpi_ioapic_remove(struct acpi_pci_root *root)
 {
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ae3fe4e..53f5965 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -614,7 +614,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	if (hotadd) {
 		pcibios_resource_survey_bus(root->bus);
 		pci_assign_unassigned_root_bus_resources(root->bus);
-		acpi_ioapic_add(root);
+		acpi_ioapic_add(root->device->handle);
 	}
 
 	pci_lock_rescan_remove();
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 55641a3..e32c356 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -25,6 +25,7 @@
 #include <linux/ioport.h>
 #include <linux/cache.h>
 #include <linux/slab.h>
+#include <linux/acpi.h>
 #include "pci.h"
 
 unsigned int pci_flags;
@@ -1779,8 +1780,10 @@ void __init pci_assign_unassigned_resources(void)
 {
 	struct pci_bus *root_bus;
 
-	list_for_each_entry(root_bus, &pci_root_buses, node)
+	list_for_each_entry(root_bus, &pci_root_buses, node) {
 		pci_assign_unassigned_root_bus_resources(root_bus);
+		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
+	}
 }
 
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5..3ed22df 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -262,6 +262,9 @@ int acpi_unmap_cpu(int cpu);
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
+int acpi_ioapic_add(acpi_handle root);
+#else
+static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
 #endif
 
 int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
-- 
1.8.3.1

Re: [PATCH V2 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1656 bytes --]

Hi,

[auto build test ERROR on pm/linux-next]
[also build test ERROR on v4.7-rc2 next-20160608]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Rui-Wang/x86-ioapic-Support-hot-removal-of-IOAPICs-present-during-boot/20160608-151907
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: mips-txx9 (attached as .config)
compiler: mips-linux-gnu-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mips 

All errors (new ones prefixed by >>):

   drivers/pci/setup-bus.c: In function 'pci_assign_unassigned_resources':
>> drivers/pci/setup-bus.c:1785:3: error: implicit declaration of function 'acpi_ioapic_add' [-Werror=implicit-function-declaration]
      acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
      ^
   cc1: some warnings being treated as errors

vim +/acpi_ioapic_add +1785 drivers/pci/setup-bus.c

  1779	void __init pci_assign_unassigned_resources(void)
  1780	{
  1781		struct pci_bus *root_bus;
  1782	
  1783		list_for_each_entry(root_bus, &pci_root_buses, node) {
  1784			pci_assign_unassigned_root_bus_resources(root_bus);
> 1785			acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
  1786		}
  1787	}
  1788	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH V2 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1656 bytes --]

Hi,

[auto build test ERROR on pm/linux-next]
[also build test ERROR on v4.7-rc2 next-20160608]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Rui-Wang/x86-ioapic-Support-hot-removal-of-IOAPICs-present-during-boot/20160608-151907
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: mips-txx9 (attached as .config)
compiler: mips-linux-gnu-gcc (Debian 5.3.1-8) 5.3.1 20160205
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mips 

All errors (new ones prefixed by >>):

   drivers/pci/setup-bus.c: In function 'pci_assign_unassigned_resources':
>> drivers/pci/setup-bus.c:1785:3: error: implicit declaration of function 'acpi_ioapic_add' [-Werror=implicit-function-declaration]
      acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
      ^
   cc1: some warnings being treated as errors

vim +/acpi_ioapic_add +1785 drivers/pci/setup-bus.c

  1779	void __init pci_assign_unassigned_resources(void)
  1780	{
  1781		struct pci_bus *root_bus;
  1782	
  1783		list_for_each_entry(root_bus, &pci_root_buses, node) {
  1784			pci_assign_unassigned_root_bus_resources(root_bus);
> 1785			acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
  1786		}
  1787	}
  1788	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 22126 bytes --]

[PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

v3: Previous versions break mips. This version fixes it.

IOAPICs present during system boot aren't added to ioapic_list,
thus are unable to be hot-removed. Fix it by calling
acpi_ioapic_add() during root bus enumeration.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 drivers/acpi/internal.h | 2 --
 drivers/acpi/ioapic.c   | 7 ++++---
 drivers/acpi/pci_root.c | 2 +-
 drivers/pci/setup-bus.c | 7 ++++++-
 include/linux/acpi.h    | 3 +++
 5 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 9bb0773..bb567a7 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
 void acpi_container_init(void);
 void acpi_memory_hotplug_init(void);
 #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
-int acpi_ioapic_add(struct acpi_pci_root *root);
 int acpi_ioapic_remove(struct acpi_pci_root *root);
 #else
-static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
 static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
 #endif
 #ifdef CONFIG_ACPI_DOCK
diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db..0f272e2 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -189,16 +189,17 @@ exit:
 	return AE_OK;
 }
 
-int acpi_ioapic_add(struct acpi_pci_root *root)
+int acpi_ioapic_add(acpi_handle root_handle)
 {
 	acpi_status status, retval = AE_OK;
 
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
 				     UINT_MAX, handle_ioapic_add, NULL,
-				     root->device->handle, (void **)&retval);
+				     root_handle, (void **)&retval);
 
 	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
 }
+EXPORT_SYMBOL_GPL(acpi_ioapic_add);
 
 int acpi_ioapic_remove(struct acpi_pci_root *root)
 {
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ae3fe4e..53f5965 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -614,7 +614,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	if (hotadd) {
 		pcibios_resource_survey_bus(root->bus);
 		pci_assign_unassigned_root_bus_resources(root->bus);
-		acpi_ioapic_add(root);
+		acpi_ioapic_add(root->device->handle);
 	}
 
 	pci_lock_rescan_remove();
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 55641a3..0658921 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -25,6 +25,7 @@
 #include <linux/ioport.h>
 #include <linux/cache.h>
 #include <linux/slab.h>
+#include <linux/acpi.h>
 #include "pci.h"
 
 unsigned int pci_flags;
@@ -1779,8 +1780,12 @@ void __init pci_assign_unassigned_resources(void)
 {
 	struct pci_bus *root_bus;
 
-	list_for_each_entry(root_bus, &pci_root_buses, node)
+	list_for_each_entry(root_bus, &pci_root_buses, node) {
 		pci_assign_unassigned_root_bus_resources(root_bus);
+#ifdef CONFIG_X86
+		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
+#endif
+	}
 }
 
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5..3ed22df 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -262,6 +262,9 @@ int acpi_unmap_cpu(int cpu);
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
+int acpi_ioapic_add(acpi_handle root);
+#else
+static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
 #endif
 
 int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
-- 
1.8.3.1

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Thomas Gleixner]

On Wed, 8 Jun 2016, Rui Wang wrote:

> v3: Previous versions break mips. This version fixes it.
> 
> IOAPICs present during system boot aren't added to ioapic_list,
> thus are unable to be hot-removed. Fix it by calling
> acpi_ioapic_add() during root bus enumeration.

Who will pick that one up? I already took 2/3 of this series as they are
independent.

Thanks,

	tglx

 

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rafael J. Wysocki]

On Friday, June 10, 2016 02:57:52 PM Thomas Gleixner wrote:
> On Wed, 8 Jun 2016, Rui Wang wrote:
> 
> > v3: Previous versions break mips. This version fixes it.
> > 
> > IOAPICs present during system boot aren't added to ioapic_list,
> > thus are unable to be hot-removed. Fix it by calling
> > acpi_ioapic_add() during root bus enumeration.
> 
> Who will pick that one up? I already took 2/3 of this series as they are
> independent.

I can pick it up.

Thanks,
Rafael

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Wed, Jun 08, 2016 at 05:32:44PM +0800, Rui Wang wrote:
> v3: Previous versions break mips. This version fixes it.
> 
> IOAPICs present during system boot aren't added to ioapic_list,
> thus are unable to be hot-removed. Fix it by calling
> acpi_ioapic_add() during root bus enumeration.
> 
> Signed-off-by: Rui Wang <rui.y.wang@intel.com>
> ---
>  drivers/acpi/internal.h | 2 --
>  drivers/acpi/ioapic.c   | 7 ++++---
>  drivers/acpi/pci_root.c | 2 +-
>  drivers/pci/setup-bus.c | 7 ++++++-
>  include/linux/acpi.h    | 3 +++
>  5 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 9bb0773..bb567a7 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
>  void acpi_container_init(void);
>  void acpi_memory_hotplug_init(void);
>  #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
> -int acpi_ioapic_add(struct acpi_pci_root *root);
>  int acpi_ioapic_remove(struct acpi_pci_root *root);
>  #else
> -static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
>  static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
>  #endif
>  #ifdef CONFIG_ACPI_DOCK
> diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
> index ccdc8db..0f272e2 100644
> --- a/drivers/acpi/ioapic.c
> +++ b/drivers/acpi/ioapic.c
> @@ -189,16 +189,17 @@ exit:
>  	return AE_OK;
>  }
>  
> -int acpi_ioapic_add(struct acpi_pci_root *root)
> +int acpi_ioapic_add(acpi_handle root_handle)
>  {
>  	acpi_status status, retval = AE_OK;
>  
> -	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
>  				     UINT_MAX, handle_ioapic_add, NULL,
> -				     root->device->handle, (void **)&retval);
> +				     root_handle, (void **)&retval);
>  
>  	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
>  }
> +EXPORT_SYMBOL_GPL(acpi_ioapic_add);
>  
>  int acpi_ioapic_remove(struct acpi_pci_root *root)
>  {
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index ae3fe4e..53f5965 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -614,7 +614,7 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	if (hotadd) {
>  		pcibios_resource_survey_bus(root->bus);
>  		pci_assign_unassigned_root_bus_resources(root->bus);
> -		acpi_ioapic_add(root);
> +		acpi_ioapic_add(root->device->handle);
>  	}
>  
>  	pci_lock_rescan_remove();
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 55641a3..0658921 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -25,6 +25,7 @@
>  #include <linux/ioport.h>
>  #include <linux/cache.h>
>  #include <linux/slab.h>
> +#include <linux/acpi.h>
>  #include "pci.h"
>  
>  unsigned int pci_flags;
> @@ -1779,8 +1780,12 @@ void __init pci_assign_unassigned_resources(void)
>  {
>  	struct pci_bus *root_bus;
>  
> -	list_for_each_entry(root_bus, &pci_root_buses, node)
> +	list_for_each_entry(root_bus, &pci_root_buses, node) {
>  		pci_assign_unassigned_root_bus_resources(root_bus);
> +#ifdef CONFIG_X86
> +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> +#endif

This seems like a strange place to call acpi_ioapic_add().  Your
object is to call acpi_ioapic_add() during root bus enumeration.

I assume we *can't* call acpi_ioapic_add() from acpi_pci_root_add() at
boot time, for some reason you'll explain.  But is there a reason we
have to call it from pci_assign_unassigned_resources() (where it
requires an ifdef) instead of from pcibios_assign_resources(), which
is already x86-specific?

In acpi_pci_root_add(), we have this:

  acpi_pci_root_add(...)
  {
    ...
    if (hotadd)
      acpi_ioapic_add(root);

So the obvious question is why don't we just remove the "if (hotadd)"
and call acpi_ioapic_add() always.

I'm sure the reason is some ordering problem, but we need a comment in
acpi_pci_root_add() about why the obvious solution doesn't work.

> +	}
>  }
>  
>  void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 288fac5..3ed22df 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -262,6 +262,9 @@ int acpi_unmap_cpu(int cpu);
>  
>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>  int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
> +int acpi_ioapic_add(acpi_handle root);
> +#else
> +static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
>  #endif
>  
>  int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
> -- 
> 1.8.3.1
> 
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

On Saturday, June 11, 2016 12:43 AM, Bjorn Helgaas wrote:
> On Wed, Jun 08, 2016 at 05:32:44PM +0800, Rui Wang wrote:
> > @@ -1779,8 +1780,12 @@ void __init
> > pci_assign_unassigned_resources(void)
> >  {
> >  	struct pci_bus *root_bus;
> >
> > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > +#ifdef CONFIG_X86
> > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > +#endif
> 
> This seems like a strange place to call acpi_ioapic_add().  Your object is to call
> acpi_ioapic_add() during root bus enumeration.
> 
> I assume we *can't* call acpi_ioapic_add() from acpi_pci_root_add() at boot
> time, for some reason you'll explain.  But is there a reason we have to call it
> from pci_assign_unassigned_resources() (where it requires an ifdef) instead
> of from pcibios_assign_resources(), which is already x86-specific?
> 
> In acpi_pci_root_add(), we have this:
> 
>   acpi_pci_root_add(...)
>   {
>     ...
>     if (hotadd)
>       acpi_ioapic_add(root);
> 
> So the obvious question is why don't we just remove the "if (hotadd)"
> and call acpi_ioapic_add() always.
> 
> I'm sure the reason is some ordering problem, but we need a comment in
> acpi_pci_root_add() about why the obvious solution doesn't work.
> 

Hi Bjorn,

Yes it's an ording issue. acpi_ioapic_add() and also ioapic_insert_resources()
have to be later than pci initialization in order to deal with IOAPICs mapped
on a PCI BAR. There's a comment about this inside pcibios_resource_survey()
above ioapic_insert_resources(). We can also add a comment inside
acpi_pci_root_add(), though.

And yes calling acpi_ioapic_add() in pcibios_assign_resources() doesn't require
ifdef CONFIG_X86. But it'll require a loop to iterate through the root buses,
and call acpi_ioapic_add() within the loop. pci_assign_unassigned_resources()
already has that loop. Do you still prefer adding it to
pcibios_assign_resources() ?

Regards,
Rui

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Sun, Jun 12, 2016 at 02:06:09PM +0800, Rui Wang wrote:
> On Saturday, June 11, 2016 12:43 AM, Bjorn Helgaas wrote:
> > On Wed, Jun 08, 2016 at 05:32:44PM +0800, Rui Wang wrote:
> > > @@ -1779,8 +1780,12 @@ void __init
> > > pci_assign_unassigned_resources(void)
> > >  {
> > >  	struct pci_bus *root_bus;
> > >
> > > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> > >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > > +#ifdef CONFIG_X86
> > > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > > +#endif
> > 
> > This seems like a strange place to call acpi_ioapic_add().  Your object is to call
> > acpi_ioapic_add() during root bus enumeration.
> > 
> > I assume we *can't* call acpi_ioapic_add() from acpi_pci_root_add() at boot
> > time, for some reason you'll explain.  But is there a reason we have to call it
> > from pci_assign_unassigned_resources() (where it requires an ifdef) instead
> > of from pcibios_assign_resources(), which is already x86-specific?
> > 
> > In acpi_pci_root_add(), we have this:
> > 
> >   acpi_pci_root_add(...)
> >   {
> >     ...
> >     if (hotadd)
> >       acpi_ioapic_add(root);
> > 
> > So the obvious question is why don't we just remove the "if (hotadd)"
> > and call acpi_ioapic_add() always.
> > 
> > I'm sure the reason is some ordering problem, but we need a comment in
> > acpi_pci_root_add() about why the obvious solution doesn't work.
> 
> Yes it's an ording issue. acpi_ioapic_add() and also ioapic_insert_resources()
> have to be later than pci initialization in order to deal with IOAPICs mapped
> on a PCI BAR. There's a comment about this inside pcibios_resource_survey()
> above ioapic_insert_resources(). We can also add a comment inside
> acpi_pci_root_add(), though.
>
> And yes calling acpi_ioapic_add() in pcibios_assign_resources() doesn't require
> ifdef CONFIG_X86. But it'll require a loop to iterate through the root buses,
> and call acpi_ioapic_add() within the loop. pci_assign_unassigned_resources()
> already has that loop. Do you still prefer adding it to
> pcibios_assign_resources() ?

ioapic_insert_resources() is x86-specific, but I'm not sure why; it
seems like it does things that should be applicable to ia64 as well.

acpi_ioapic_add() is not x86-specific, and it is called from
acpi_pci_root_add() for the hot-add case.  You're adding an
x86-xpecific call in pci_assign_unassigned_resources().  Why should
the hot-add case be for all arches, but the boot-time case only for
x86?

RE: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

On Friday, June 17, 2016 1:10 AM, Bjorn Helgaas wrote:
> ioapic_insert_resources() is x86-specific, but I'm not sure why; it seems
> like it does things that should be applicable to ia64 as well.
> 
> acpi_ioapic_add() is not x86-specific, and it is called from
> acpi_pci_root_add() for the hot-add case.  You're adding an x86-xpecific call
> in pci_assign_unassigned_resources().  Why should the hot-add case be for
> all arches, but the boot-time case only for x86?

Hi Bjorn,

It turns out that IOAPIC hotplug has not been pursued on ia64. There were
demos showing CPU sockets online/offline on ia64 but the CPUs had no IIO,
thus no IOAPIC hotplug.

So to answer the first question:
ioapic_insert_resources() is x86-specific because it's inserting what has
been setup in io_apic_init_mappings() which, through mpc_ioapic_addr(), is
capable of handling both the static case (acpi_parse_ioapic(), etc.) and the
hotplug case (acpi_ioapic_add()). But on ia64, there's only the static
case through acpi_parse_iosapic(), no need for the hotplug case yet.

To answer the second question:
acpi_ioapic_add() is in effect x86-specific, because it's an empty function
when CONFIG_ACPI_HOTPLUG_IOAPIC isn't defined. And CONFIG_ACPI_HOTPLUG_IOAPIC
depends on CONFIG_X86_IO_APIC (see drivers/acpi/Kconfig). This was introduced
in c183619b6 (x86/irq, ACPI: Implement ACPI driver to support IOAPIC hotplug).
That commit shows the dependency.

I'll send a newer version with comments explaining these.

Thanks
Rui

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Wed, Jun 22, 2016 at 03:13:32PM +0800, Rui Wang wrote:
> On Friday, June 17, 2016 1:10 AM, Bjorn Helgaas wrote:
> > ioapic_insert_resources() is x86-specific, but I'm not sure why; it seems
> > like it does things that should be applicable to ia64 as well.
> > 
> > acpi_ioapic_add() is not x86-specific, and it is called from
> > acpi_pci_root_add() for the hot-add case.  You're adding an x86-xpecific call
> > in pci_assign_unassigned_resources().  Why should the hot-add case be for
> > all arches, but the boot-time case only for x86?
> 
> Hi Bjorn,
> 
> It turns out that IOAPIC hotplug has not been pursued on ia64. There were
> demos showing CPU sockets online/offline on ia64 but the CPUs had no IIO,
> thus no IOAPIC hotplug.

That doesn't mean we need to write code that's gratuitously x86-specific.

> So to answer the first question:
> ioapic_insert_resources() is x86-specific because it's inserting what has
> been setup in io_apic_init_mappings() which, through mpc_ioapic_addr(), is
> capable of handling both the static case (acpi_parse_ioapic(), etc.) and the
> hotplug case (acpi_ioapic_add()). But on ia64, there's only the static
> case through acpi_parse_iosapic(), no need for the hotplug case yet.

ioapic_insert_resources() inserts IOAPIC resources on x86.  Where are
IOSAPIC resources inserted on ia64?

> To answer the second question:
> acpi_ioapic_add() is in effect x86-specific, because it's an empty function
> when CONFIG_ACPI_HOTPLUG_IOAPIC isn't defined. And CONFIG_ACPI_HOTPLUG_IOAPIC
> depends on CONFIG_X86_IO_APIC (see drivers/acpi/Kconfig). This was introduced
> in c183619b6 (x86/irq, ACPI: Implement ACPI driver to support IOAPIC hotplug).
> That commit shows the dependency.
> 
> I'll send a newer version with comments explaining these.

I'd rather have code that is not x86-specific than comments explaining why
the code is x86-specific.

Re: [PATCH V3 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

On Wed, June 22, 2016 10:54 PM Bjorn Helgaas wrote:
> On Wed, Jun 22, 2016 at 03:13:32PM +0800, Rui Wang wrote:
> > On Friday, June 17, 2016 1:10 AM, Bjorn Helgaas wrote:
> > > ioapic_insert_resources() is x86-specific, but I'm not sure why; it
> > > seems like it does things that should be applicable to ia64 as well.
> > >
> > > acpi_ioapic_add() is not x86-specific, and it is called from
> > > acpi_pci_root_add() for the hot-add case.  You're adding an
> > > x86-xpecific call in pci_assign_unassigned_resources().  Why should
> > > the hot-add case be for all arches, but the boot-time case only for x86?
> >
> > Hi Bjorn,
> >
> > It turns out that IOAPIC hotplug has not been pursued on ia64. There
> > were demos showing CPU sockets online/offline on ia64 but the CPUs had
> > no IIO, thus no IOAPIC hotplug.
> 
> That doesn't mean we need to write code that's gratuitously x86-specific.
> 
> > So to answer the first question:
> > ioapic_insert_resources() is x86-specific because it's inserting what
> > has been setup in io_apic_init_mappings() which, through
> > mpc_ioapic_addr(), is capable of handling both the static case
> > (acpi_parse_ioapic(), etc.) and the hotplug case (acpi_ioapic_add()).
> > But on ia64, there's only the static case through acpi_parse_iosapic(), no
> need for the hotplug case yet.
> 
> ioapic_insert_resources() inserts IOAPIC resources on x86.  Where are
> IOSAPIC resources inserted on ia64?
> 
I'm not sure. Its physical address from MADT is parsed in acpi_parse_iosapic()
and ioremap()'d in iosapic_init(). Only the virtual address is recorded.
The physical address doesn't seem to be recorded and inserted explicitly. But
it could be in a "_CRS" and gets inserted implicitly. The iosapic on ia64 uses
its own data structures very different from the ioapic on x86. I think it's
hard to unify them using a common set of functions, without rewriting the whole
framework.

Thanks
Rui

[PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

v4: Add comments explaining when to call acpi_ioapic_add().
v3: Previous versions break mips. This version fixes it.

IOAPICs present during system boot aren't added to ioapic_list,
thus are unable to be hot-removed. Fix it by calling
acpi_ioapic_add() during root bus enumeration.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 drivers/acpi/internal.h |  2 --
 drivers/acpi/ioapic.c   |  7 ++++---
 drivers/acpi/pci_root.c | 13 ++++++++++++-
 drivers/pci/setup-bus.c |  7 ++++++-
 include/linux/acpi.h    |  3 +++
 5 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 27cc7fe..6d8e67e 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
 void acpi_container_init(void);
 void acpi_memory_hotplug_init(void);
 #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
-int acpi_ioapic_add(struct acpi_pci_root *root);
 int acpi_ioapic_remove(struct acpi_pci_root *root);
 #else
-static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
 static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
 #endif
 #ifdef CONFIG_ACPI_DOCK
diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db..0f272e2 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -189,16 +189,17 @@ exit:
 	return AE_OK;
 }
 
-int acpi_ioapic_add(struct acpi_pci_root *root)
+int acpi_ioapic_add(acpi_handle root_handle)
 {
 	acpi_status status, retval = AE_OK;
 
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
 				     UINT_MAX, handle_ioapic_add, NULL,
-				     root->device->handle, (void **)&retval);
+				     root_handle, (void **)&retval);
 
 	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
 }
+EXPORT_SYMBOL_GPL(acpi_ioapic_add);
 
 int acpi_ioapic_remove(struct acpi_pci_root *root)
 {
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ae3fe4e..31e4440 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -614,7 +614,18 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	if (hotadd) {
 		pcibios_resource_survey_bus(root->bus);
 		pci_assign_unassigned_root_bus_resources(root->bus);
-		acpi_ioapic_add(root);
+
+		/*
+ 		 * This is only called for the hotadd case. For the boot-time
+ 		 * case, we need to wait until after PCI initialization in
+ 		 * order to deal with IOAPICs mapped in on a PCI BAR.
+ 		 *
+ 		 * This is currently x86-specific, because acpi_ioapic_add()
+ 		 * is an empty function without CONFIG_ACPI_HOTPLUG_IOAPIC.
+ 		 * And CONFIG_ACPI_HOTPLUG_IOAPIC depends on CONFIG_X86_IO_APIC
+ 		 * (see drivers/acpi/Kconfig).
+ 		 */
+		acpi_ioapic_add(root->device->handle);
 	}
 
 	pci_lock_rescan_remove();
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 55641a3..0658921 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -25,6 +25,7 @@
 #include <linux/ioport.h>
 #include <linux/cache.h>
 #include <linux/slab.h>
+#include <linux/acpi.h>
 #include "pci.h"
 
 unsigned int pci_flags;
@@ -1779,8 +1780,12 @@ void __init pci_assign_unassigned_resources(void)
 {
 	struct pci_bus *root_bus;
 
-	list_for_each_entry(root_bus, &pci_root_buses, node)
+	list_for_each_entry(root_bus, &pci_root_buses, node) {
 		pci_assign_unassigned_root_bus_resources(root_bus);
+#ifdef CONFIG_X86
+		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
+#endif
+	}
 }
 
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5..3ed22df 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -262,6 +262,9 @@ int acpi_unmap_cpu(int cpu);
 
 #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
 int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
+int acpi_ioapic_add(acpi_handle root);
+#else
+static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
 #endif
 
 int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
-- 
1.8.3.1

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Wed, Jun 22, 2016 at 03:40:19PM +0800, Rui Wang wrote:
> v4: Add comments explaining when to call acpi_ioapic_add().
> v3: Previous versions break mips. This version fixes it.
> 
> IOAPICs present during system boot aren't added to ioapic_list,
> thus are unable to be hot-removed. Fix it by calling
> acpi_ioapic_add() during root bus enumeration.
> 
> Signed-off-by: Rui Wang <rui.y.wang@intel.com>
> ---
>  drivers/acpi/internal.h |  2 --
>  drivers/acpi/ioapic.c   |  7 ++++---
>  drivers/acpi/pci_root.c | 13 ++++++++++++-
>  drivers/pci/setup-bus.c |  7 ++++++-
>  include/linux/acpi.h    |  3 +++
>  5 files changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 27cc7fe..6d8e67e 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
>  void acpi_container_init(void);
>  void acpi_memory_hotplug_init(void);
>  #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
> -int acpi_ioapic_add(struct acpi_pci_root *root);
>  int acpi_ioapic_remove(struct acpi_pci_root *root);
>  #else
> -static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
>  static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
>  #endif
>  #ifdef CONFIG_ACPI_DOCK
> diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
> index ccdc8db..0f272e2 100644
> --- a/drivers/acpi/ioapic.c
> +++ b/drivers/acpi/ioapic.c
> @@ -189,16 +189,17 @@ exit:
>  	return AE_OK;
>  }
>  
> -int acpi_ioapic_add(struct acpi_pci_root *root)
> +int acpi_ioapic_add(acpi_handle root_handle)
>  {
>  	acpi_status status, retval = AE_OK;
>  
> -	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
>  				     UINT_MAX, handle_ioapic_add, NULL,
> -				     root->device->handle, (void **)&retval);
> +				     root_handle, (void **)&retval);
>  
>  	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
>  }
> +EXPORT_SYMBOL_GPL(acpi_ioapic_add);
>  
>  int acpi_ioapic_remove(struct acpi_pci_root *root)
>  {
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index ae3fe4e..31e4440 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -614,7 +614,18 @@ static int acpi_pci_root_add(struct acpi_device *device,
>  	if (hotadd) {
>  		pcibios_resource_survey_bus(root->bus);
>  		pci_assign_unassigned_root_bus_resources(root->bus);
> -		acpi_ioapic_add(root);
> +
> +		/*
> + 		 * This is only called for the hotadd case. For the boot-time
> + 		 * case, we need to wait until after PCI initialization in
> + 		 * order to deal with IOAPICs mapped in on a PCI BAR.
> + 		 *
> + 		 * This is currently x86-specific, because acpi_ioapic_add()
> + 		 * is an empty function without CONFIG_ACPI_HOTPLUG_IOAPIC.
> + 		 * And CONFIG_ACPI_HOTPLUG_IOAPIC depends on CONFIG_X86_IO_APIC
> + 		 * (see drivers/acpi/Kconfig).
> + 		 */
> +		acpi_ioapic_add(root->device->handle);
>  	}
>  
>  	pci_lock_rescan_remove();
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 55641a3..0658921 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -25,6 +25,7 @@
>  #include <linux/ioport.h>
>  #include <linux/cache.h>
>  #include <linux/slab.h>
> +#include <linux/acpi.h>
>  #include "pci.h"
>  
>  unsigned int pci_flags;
> @@ -1779,8 +1780,12 @@ void __init pci_assign_unassigned_resources(void)
>  {
>  	struct pci_bus *root_bus;
>  
> -	list_for_each_entry(root_bus, &pci_root_buses, node)
> +	list_for_each_entry(root_bus, &pci_root_buses, node) {
>  		pci_assign_unassigned_root_bus_resources(root_bus);
> +#ifdef CONFIG_X86
> +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> +#endif

Doesn't this do the right thing even if you omit the #ifdefs, since you
define a stub function below?

> +	}
>  }
>  
>  void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 288fac5..3ed22df 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -262,6 +262,9 @@ int acpi_unmap_cpu(int cpu);
>  
>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>  int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
> +int acpi_ioapic_add(acpi_handle root);
> +#else
> +static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
>  #endif
>  
>  int acpi_register_ioapic(acpi_handle handle, u64 phys_addr, u32 gsi_base);
> -- 
> 1.8.3.1
> 

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Unknown,]

From: Rui Wang <rui.y.wang@intel.com>

On Wed, June 22, 2016 11:15 PM Bjorn Helgaas wrote:
> [...]
> > @@ -1779,8 +1780,12 @@ void __init
> > pci_assign_unassigned_resources(void)
> >  {
> >  	struct pci_bus *root_bus;
> >
> > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > +#ifdef CONFIG_X86
> > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > +#endif
> 
> Doesn't this do the right thing even if you omit the #ifdefs, since you
> define a stub function below?
> 

No. Without the '#ifdef CONFIG_X86' it breaks MIPS arch. The stub function is
within 'ifdef CONFIG_ACPI'. On archs without ACPI it doesn't compile due to
'undefined reference to acpi_ioapic_add'.

Thanks
Rui

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[@ 2016-06-23 5:11 UTC (permalink / raw)]

From: Rui Wang <rui.y.wang@intel.com>

On Wed, June 22, 2016 11:15 PM Bjorn Helgaas wrote:
> [...]
> > @@ -1779,8 +1780,12 @@ void __init
> > pci_assign_unassigned_resources(void)
> >  {
> >  	struct pci_bus *root_bus;
> >
> > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > +#ifdef CONFIG_X86
> > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > +#endif
> 
> Doesn't this do the right thing even if you omit the #ifdefs, since you
> define a stub function below?
> 

No. Without the '#ifdef CONFIG_X86' it breaks MIPS arch. The stub function is
within 'ifdef CONFIG_ACPI'. On archs without ACPI it doesn't compile due to
'undefined reference to acpi_ioapic_add'.

Thanks
Rui

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[@ 2016-06-23 5:11 UTC (permalink / raw)]

From: Rui Wang <rui.y.wang@intel.com>

On Wed, June 22, 2016 11:15 PM Bjorn Helgaas wrote:
> [...]
> > @@ -1779,8 +1780,12 @@ void __init
> > pci_assign_unassigned_resources(void)
> >  {
> >  	struct pci_bus *root_bus;
> >
> > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > +#ifdef CONFIG_X86
> > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > +#endif
> 
> Doesn't this do the right thing even if you omit the #ifdefs, since you
> define a stub function below?
> 

No. Without the '#ifdef CONFIG_X86' it breaks MIPS arch. The stub function is
within 'ifdef CONFIG_ACPI'. On archs without ACPI it doesn't compile due to
'undefined reference to acpi_ioapic_add'.

Thanks
Rui

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Thu, Jun 23, 2016 at 01:11:41PM +0800,  wrote:
> From: Rui Wang <rui.y.wang@intel.com>
> 
> On Wed, June 22, 2016 11:15 PM Bjorn Helgaas wrote:
> > [...]
> > > @@ -1779,8 +1780,12 @@ void __init
> > > pci_assign_unassigned_resources(void)
> > >  {
> > >  	struct pci_bus *root_bus;
> > >
> > > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> > >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > > +#ifdef CONFIG_X86
> > > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > > +#endif
> > 
> > Doesn't this do the right thing even if you omit the #ifdefs, since you
> > define a stub function below?
> > 
> 
> No. Without the '#ifdef CONFIG_X86' it breaks MIPS arch. The stub function is
> within 'ifdef CONFIG_ACPI'. On archs without ACPI it doesn't compile due to
> 'undefined reference to acpi_ioapic_add'.

But this *could* be made to work by defining a stub for the
non-CONFIG_ACPI case.  That's what we generally do to avoid ifdefs in
the code.

Bjorn

Re: [PATCH V4 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

On Fri, Jun 24, 2016 1:35 AM Bjorn Helgaas wrote:
> On Thu, Jun 23, 2016 at 01:11:41PM +0800, Rui Wang wrote:
> > On Wed, June 22, 2016 11:15 PM Bjorn Helgaas wrote:
> > > [...]
> > > > @@ -1779,8 +1780,12 @@ void __init
> > > > pci_assign_unassigned_resources(void)
> > > >  {
> > > >  	struct pci_bus *root_bus;
> > > >
> > > > -	list_for_each_entry(root_bus, &pci_root_buses, node)
> > > > +	list_for_each_entry(root_bus, &pci_root_buses, node) {
> > > >  		pci_assign_unassigned_root_bus_resources(root_bus);
> > > > +#ifdef CONFIG_X86
> > > > +		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
> > > > +#endif
> > >
> > > Doesn't this do the right thing even if you omit the #ifdefs, since
> > > you define a stub function below?
> > >
> >
> > No. Without the '#ifdef CONFIG_X86' it breaks MIPS arch. The stub
> > function is within 'ifdef CONFIG_ACPI'. On archs without ACPI it
> > doesn't compile due to 'undefined reference to acpi_ioapic_add'.
> 
> But this *could* be made to work by defining a stub for the non-
> CONFIG_ACPI case.  That's what we generally do to avoid ifdefs in the code.

That can be done. I'll make the change and do some cross-compiling tests first.

Thanks
Rui

[PATCH V5 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

v5: Remove #ifdef CONFIG_X86 from setup-bus.c, making it neutral to archs.
v4: Add comments explaining when to call acpi_ioapic_add().
v3: Previous versions break mips. This version fixes it.

IOAPICs present during system boot aren't added to ioapic_list,
thus are unable to be hot-removed. Fix it by calling
acpi_ioapic_add() during root bus enumeration.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 drivers/acpi/internal.h |  2 --
 drivers/acpi/ioapic.c   |  7 ++++---
 drivers/acpi/pci_root.c | 13 ++++++++++++-
 drivers/pci/setup-bus.c |  5 ++++-
 include/linux/acpi.h    |  6 ++++++
 5 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 27cc7fe..6d8e67e 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -40,10 +40,8 @@ int acpi_sysfs_init(void);
 void acpi_container_init(void);
 void acpi_memory_hotplug_init(void);
 #ifdef	CONFIG_ACPI_HOTPLUG_IOAPIC
-int acpi_ioapic_add(struct acpi_pci_root *root);
 int acpi_ioapic_remove(struct acpi_pci_root *root);
 #else
-static inline int acpi_ioapic_add(struct acpi_pci_root *root) { return 0; }
 static inline int acpi_ioapic_remove(struct acpi_pci_root *root) { return 0; }
 #endif
 #ifdef CONFIG_ACPI_DOCK
diff --git a/drivers/acpi/ioapic.c b/drivers/acpi/ioapic.c
index ccdc8db..0f272e2 100644
--- a/drivers/acpi/ioapic.c
+++ b/drivers/acpi/ioapic.c
@@ -189,16 +189,17 @@ exit:
 	return AE_OK;
 }
 
-int acpi_ioapic_add(struct acpi_pci_root *root)
+int acpi_ioapic_add(acpi_handle root_handle)
 {
 	acpi_status status, retval = AE_OK;
 
-	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root->device->handle,
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, root_handle,
 				     UINT_MAX, handle_ioapic_add, NULL,
-				     root->device->handle, (void **)&retval);
+				     root_handle, (void **)&retval);
 
 	return ACPI_SUCCESS(status) && ACPI_SUCCESS(retval) ? 0 : -ENODEV;
 }
+EXPORT_SYMBOL_GPL(acpi_ioapic_add);
 
 int acpi_ioapic_remove(struct acpi_pci_root *root)
 {
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index ae3fe4e..31e4440 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -614,7 +614,18 @@ static int acpi_pci_root_add(struct acpi_device *device,
 	if (hotadd) {
 		pcibios_resource_survey_bus(root->bus);
 		pci_assign_unassigned_root_bus_resources(root->bus);
-		acpi_ioapic_add(root);
+
+		/*
+ 		 * This is only called for the hotadd case. For the boot-time
+ 		 * case, we need to wait until after PCI initialization in
+ 		 * order to deal with IOAPICs mapped in on a PCI BAR.
+ 		 *
+ 		 * This is currently x86-specific, because acpi_ioapic_add()
+ 		 * is an empty function without CONFIG_ACPI_HOTPLUG_IOAPIC.
+ 		 * And CONFIG_ACPI_HOTPLUG_IOAPIC depends on CONFIG_X86_IO_APIC
+ 		 * (see drivers/acpi/Kconfig).
+ 		 */
+		acpi_ioapic_add(root->device->handle);
 	}
 
 	pci_lock_rescan_remove();
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 55641a3..e32c356 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -25,6 +25,7 @@
 #include <linux/ioport.h>
 #include <linux/cache.h>
 #include <linux/slab.h>
+#include <linux/acpi.h>
 #include "pci.h"
 
 unsigned int pci_flags;
@@ -1779,8 +1780,10 @@ void __init pci_assign_unassigned_resources(void)
 {
 	struct pci_bus *root_bus;
 
-	list_for_each_entry(root_bus, &pci_root_buses, node)
+	list_for_each_entry(root_bus, &pci_root_buses, node) {
 		pci_assign_unassigned_root_bus_resources(root_bus);
+		acpi_ioapic_add(ACPI_HANDLE(root_bus->bridge));
+	}
 }
 
 void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5..f5114dc 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -680,6 +680,12 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
 
 #endif	/* !CONFIG_ACPI */
 
+#ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
+int acpi_ioapic_add(acpi_handle root);
+#else
+static inline int acpi_ioapic_add(acpi_handle root) { return 0; }
+#endif
+
 #ifdef CONFIG_ACPI
 void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
 			       u32 pm1a_ctrl,  u32 pm1b_ctrl));
-- 
1.8.3.1

Re: [PATCH V5 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Bjorn Helgaas]

On Sun, Jun 26, 2016 at 11:44:57AM +0800, Rui Wang wrote:
> v5: Remove #ifdef CONFIG_X86 from setup-bus.c, making it neutral to archs.
> v4: Add comments explaining when to call acpi_ioapic_add().
> v3: Previous versions break mips. This version fixes it.
> 
> IOAPICs present during system boot aren't added to ioapic_list,
> thus are unable to be hot-removed. Fix it by calling
> acpi_ioapic_add() during root bus enumeration.
> 
> Signed-off-by: Rui Wang <rui.y.wang@intel.com>

Hi Rui,

Where are we at with this?  If there's anything that still needs to be
merged, can you rebase it to v4.8-rc1 and post a new, complete,
series?

Bjorn

Re: [PATCH V5 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rui Wang]

On Tuesday, Aug 9, 2016 4:23 AM, Bjorn Helgaas wrote:
> On Sun, Jun 26, 2016 at 11:44:57AM +0800, Rui Wang wrote:
> > v5: Remove #ifdef CONFIG_X86 from setup-bus.c, making it neutral to
> archs.
> > v4: Add comments explaining when to call acpi_ioapic_add().
> > v3: Previous versions break mips. This version fixes it.
> >
> > IOAPICs present during system boot aren't added to ioapic_list, thus
> > are unable to be hot-removed. Fix it by calling
> > acpi_ioapic_add() during root bus enumeration.
> >
> > Signed-off-by: Rui Wang <rui.y.wang@intel.com>
> 
> Hi Rui,
> 
> Where are we at with this?  If there's anything that still needs to be merged,
> can you rebase it to v4.8-rc1 and post a new, complete, series?
> 
Hi Bjorn,

Yes. These patches are needed for IOAPIC hotplug to work.

So Thomas & Rafael, any advice?

Thanks
Rui

Re: [PATCH V5 1/3] x86/ioapic: Support hot-removal of IOAPICs present during boot

[Rafael J. Wysocki]

On Tue, Aug 9, 2016 at 5:23 AM, Rui Wang <rui.y.wang@intel.com> wrote:
> On Tuesday, Aug 9, 2016 4:23 AM, Bjorn Helgaas wrote:
>> On Sun, Jun 26, 2016 at 11:44:57AM +0800, Rui Wang wrote:
>> > v5: Remove #ifdef CONFIG_X86 from setup-bus.c, making it neutral to
>> archs.
>> > v4: Add comments explaining when to call acpi_ioapic_add().
>> > v3: Previous versions break mips. This version fixes it.
>> >
>> > IOAPICs present during system boot aren't added to ioapic_list, thus
>> > are unable to be hot-removed. Fix it by calling
>> > acpi_ioapic_add() during root bus enumeration.
>> >
>> > Signed-off-by: Rui Wang <rui.y.wang@intel.com>
>>
>> Hi Rui,
>>
>> Where are we at with this?  If there's anything that still needs to be merged,
>> can you rebase it to v4.8-rc1 and post a new, complete, series?
>>
> Hi Bjorn,
>
> Yes. These patches are needed for IOAPIC hotplug to work.
>
> So Thomas & Rafael, any advice?

Can you please do as per what Bjorn said?  That is, rebase the series
on top of 4.8-rc1 and post it afresh?

Thanks,
Rafael

[PATCH V2 2/3] x86/ioapic: Fix wrong pointers in ioapic_setup_resources()

[Rui Wang]

On a 4-socket brickland, hot-removing one ioapic is fine. Hot-removing
the 2nd one causes panic in mp_unregister_ioapic() while calling
release_resource(). It is because the iomem_res pointer has already been
released when removing the first ioapic.

Fix it by assigning the correct pointers to ioapics[i].iomem_res in
ioapic_setup_resources().

To explain the use of &res[num] here: res is assigned to ioapic_resources,
and later in ioapic_insert_resources() we do

	struct resource *r = ioapic_resources;
        for_each_ioapic(i) {
                insert_resource(&iomem_resource, r);
                r++;
        }

Here r is treated as an arry of struct resource, and the r++ ensures that
each element of the array is inserted separately. Thus we should call
release_resouce() on each element at &res[num].

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 arch/x86/kernel/apic/io_apic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 84e33ff..446702e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2588,8 +2588,8 @@ static struct resource * __init ioapic_setup_resources(void)
 		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
+		ioapics[i].iomem_res = &res[num];
 		num++;
-		ioapics[i].iomem_res = res;
 	}
 
 	ioapic_resources = res;
-- 
1.8.3.1

[tip:x86/urgent] x86/ioapic: Fix wrong pointers in ioapic_setup_resources()

[tip-bot for Rui Wang]

Commit-ID:  0e1c672041819474181a41ce07e4734750789170
Gitweb:     http://git.kernel.org/tip/0e1c672041819474181a41ce07e4734750789170
Author:     Rui Wang <rui.y.wang@intel.com>
AuthorDate: Wed, 8 Jun 2016 14:59:52 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 10 Jun 2016 11:41:47 +0200

x86/ioapic: Fix wrong pointers in ioapic_setup_resources()

On a 4-socket brickland, hot-removing one ioapic is fine. Hot-removing
the 2nd one causes panic in mp_unregister_ioapic() while calling
release_resource(). It is because the iomem_res pointer has already been
released when removing the first ioapic.

To explain the use of &res[num] here: res is assigned to ioapic_resources,
and later in ioapic_insert_resources() we do

	struct resource *r = ioapic_resources;
        for_each_ioapic(i) {
                insert_resource(&iomem_resource, r);
                r++;
        }

Here r is treated as an arry of struct resource, and the r++ ensures that
each element of the array is inserted separately. Thus we should call
release_resouce() on each element at &res[num].

Fix it by assigning the correct pointers to ioapics[i].iomem_res in
ioapic_setup_resources().

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1465369193-4816-3-git-send-email-rui.y.wang@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 arch/x86/kernel/apic/io_apic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 84e33ff..446702e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2588,8 +2588,8 @@ static struct resource * __init ioapic_setup_resources(void)
 		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
+		ioapics[i].iomem_res = &res[num];
 		num++;
-		ioapics[i].iomem_res = res;
 	}
 
 	ioapic_resources = res;

[tip:x86/apic] x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

[tip-bot for Rui Wang]

Commit-ID:  3d98217b6726e0c342ac6363346bd9751fd61ec9
Gitweb:     http://git.kernel.org/tip/3d98217b6726e0c342ac6363346bd9751fd61ec9
Author:     Rui Wang <rui.y.wang@intel.com>
AuthorDate: Wed, 8 Jun 2016 14:59:52 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 10 Jun 2016 13:55:03 +0200

x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

On a 4-socket Brickland system, hot-removing one ioapic is fine.
Hot-removing the 2nd one causes panic in mp_unregister_ioapic()
while calling release_resource().

It is because the iomem_res pointer has already been released
when removing the first ioapic.

To explain the use of &res[num] here: res is assigned to ioapic_resources,
and later in ioapic_insert_resources() we do:

	struct resource *r = ioapic_resources;

        for_each_ioapic(i) {
                insert_resource(&iomem_resource, r);
                r++;
        }

Here 'r' is treated as an arry of 'struct resource', and the r++ ensures
that each element of the array is inserted separately. Thus we should call
release_resouce() on each element at &res[num].

Fix it by assigning the correct pointers to ioapics[i].iomem_res in
ioapic_setup_resources().

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1465369193-4816-3-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/apic/io_apic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 84e33ff..446702e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2588,8 +2588,8 @@ static struct resource * __init ioapic_setup_resources(void)
 		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
+		ioapics[i].iomem_res = &res[num];
 		num++;
-		ioapics[i].iomem_res = res;
 	}
 
 	ioapic_resources = res;

[tip:x86/urgent] x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

[tip-bot for Rui Wang]

Commit-ID:  9d98bcec731756b8688b59ec998707924d716d7b
Gitweb:     http://git.kernel.org/tip/9d98bcec731756b8688b59ec998707924d716d7b
Author:     Rui Wang <rui.y.wang@intel.com>
AuthorDate: Wed, 8 Jun 2016 14:59:52 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 10 Jun 2016 14:45:54 +0200

x86/ioapic: Fix incorrect pointers in ioapic_setup_resources()

On a 4-socket Brickland system, hot-removing one ioapic is fine.
Hot-removing the 2nd one causes panic in mp_unregister_ioapic()
while calling release_resource().

It is because the iomem_res pointer has already been released
when removing the first ioapic.

To explain the use of &res[num] here: res is assigned to ioapic_resources,
and later in ioapic_insert_resources() we do:

	struct resource *r = ioapic_resources;

        for_each_ioapic(i) {
                insert_resource(&iomem_resource, r);
                r++;
        }

Here 'r' is treated as an arry of 'struct resource', and the r++ ensures
that each element of the array is inserted separately. Thus we should call
release_resouce() on each element at &res[num].

Fix it by assigning the correct pointers to ioapics[i].iomem_res in
ioapic_setup_resources().

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1465369193-4816-3-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/apic/io_apic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 84e33ff..446702e 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2588,8 +2588,8 @@ static struct resource * __init ioapic_setup_resources(void)
 		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
+		ioapics[i].iomem_res = &res[num];
 		num++;
-		ioapics[i].iomem_res = res;
 	}
 
 	ioapic_resources = res;

[PATCH V2 3/3] x86/ioapic: Simplify ioapic_setup_resources()

[Rui Wang]

Optimize the function by removing the variable 'num'.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
---
 arch/x86/kernel/apic/io_apic.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 446702e..e587295 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2567,29 +2567,25 @@ static struct resource * __init ioapic_setup_resources(void)
 	unsigned long n;
 	struct resource *res;
 	char *mem;
-	int i, num = 0;
+	int i;
 
-	for_each_ioapic(i)
-		num++;
-	if (num == 0)
+	if (nr_ioapics == 0)
 		return NULL;
 
 	n = IOAPIC_RESOURCE_NAME_SIZE + sizeof(struct resource);
-	n *= num;
+	n *= nr_ioapics;
 
 	mem = alloc_bootmem(n);
 	res = (void *)mem;
 
-	mem += sizeof(struct resource) * num;
+	mem += sizeof(struct resource) * nr_ioapics;
 
-	num = 0;
 	for_each_ioapic(i) {
-		res[num].name = mem;
-		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+		res[i].name = mem;
+		res[i].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
-		ioapics[i].iomem_res = &res[num];
-		num++;
+		ioapics[i].iomem_res = &res[i];
 	}
 
 	ioapic_resources = res;
-- 
1.8.3.1

[tip:x86/apic] x86/ioapic: Simplify ioapic_setup_resources()

[tip-bot for Rui Wang]

Commit-ID:  0286d538082b854b4e1f05b29c23556fa344e145
Gitweb:     http://git.kernel.org/tip/0286d538082b854b4e1f05b29c23556fa344e145
Author:     Rui Wang <rui.y.wang@intel.com>
AuthorDate: Wed, 8 Jun 2016 14:59:53 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 10 Jun 2016 11:43:52 +0200

x86/ioapic: Simplify ioapic_setup_resources()

Optimize the function by removing the variable 'num'.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1465369193-4816-4-git-send-email-rui.y.wang@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 arch/x86/kernel/apic/io_apic.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 446702e..e587295 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2567,29 +2567,25 @@ static struct resource * __init ioapic_setup_resources(void)
 	unsigned long n;
 	struct resource *res;
 	char *mem;
-	int i, num = 0;
+	int i;
 
-	for_each_ioapic(i)
-		num++;
-	if (num == 0)
+	if (nr_ioapics == 0)
 		return NULL;
 
 	n = IOAPIC_RESOURCE_NAME_SIZE + sizeof(struct resource);
-	n *= num;
+	n *= nr_ioapics;
 
 	mem = alloc_bootmem(n);
 	res = (void *)mem;
 
-	mem += sizeof(struct resource) * num;
+	mem += sizeof(struct resource) * nr_ioapics;
 
-	num = 0;
 	for_each_ioapic(i) {
-		res[num].name = mem;
-		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+		res[i].name = mem;
+		res[i].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
-		ioapics[i].iomem_res = &res[num];
-		num++;
+		ioapics[i].iomem_res = &res[i];
 	}
 
 	ioapic_resources = res;

[tip:x86/apic] x86/ioapic: Simplify ioapic_setup_resources()

[tip-bot for Rui Wang]

Commit-ID:  4855531eb8582a98cb905d2baf86021254d7a675
Gitweb:     http://git.kernel.org/tip/4855531eb8582a98cb905d2baf86021254d7a675
Author:     Rui Wang <rui.y.wang@intel.com>
AuthorDate: Wed, 8 Jun 2016 14:59:53 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 10 Jun 2016 14:48:18 +0200

x86/ioapic: Simplify ioapic_setup_resources()

Optimize the function by removing the variable 'num'.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: tony.luck@intel.com
Cc: linux-pci@vger.kernel.org
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1465369193-4816-4-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/apic/io_apic.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 446702e..e587295 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2567,29 +2567,25 @@ static struct resource * __init ioapic_setup_resources(void)
 	unsigned long n;
 	struct resource *res;
 	char *mem;
-	int i, num = 0;
+	int i;
 
-	for_each_ioapic(i)
-		num++;
-	if (num == 0)
+	if (nr_ioapics == 0)
 		return NULL;
 
 	n = IOAPIC_RESOURCE_NAME_SIZE + sizeof(struct resource);
-	n *= num;
+	n *= nr_ioapics;
 
 	mem = alloc_bootmem(n);
 	res = (void *)mem;
 
-	mem += sizeof(struct resource) * num;
+	mem += sizeof(struct resource) * nr_ioapics;
 
-	num = 0;
 	for_each_ioapic(i) {
-		res[num].name = mem;
-		res[num].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+		res[i].name = mem;
+		res[i].flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 		snprintf(mem, IOAPIC_RESOURCE_NAME_SIZE, "IOAPIC %u", i);
 		mem += IOAPIC_RESOURCE_NAME_SIZE;
-		ioapics[i].iomem_res = &res[num];
-		num++;
+		ioapics[i].iomem_res = &res[i];
 	}
 
 	ioapic_resources = res;