acpi: Fix CPU hot removal problem

PATCH Superseded canquan.shen 2 participants 3 messages Sep 14, 2011 – Sep 15, 2011 ACPI

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canquan.shen

author

2011-09-14 02:18 UTC #0 lore raw

PATCH v3 1/1 acpi: Fix CPU hot removal problem

We run linux as a guest in Xen environment. When we used the xen tools (xm vcpu-set <n>) to hot add and remove vcpu to and from the guest, we encountered the failure on vcpu removal. We found the reason is that it didn't go to really remove cpu in the cpu removal code path.

This patch adds acpi_bus_trim in acpi_process_hotplug_notify to fix this issue. With this patch, it works fine for us.

Signed-off-by Shen canquan <[email protected]>

---
 drivers/acpi/processor_driver.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

drivers/acpi/processor_driver.c +7 -0

index a4e0f1b..0856ef8 100644
@@ -677,6 +677,13 @@ static void acpi_processor_hotplug_notify(acpi_handle handle,
 				    "Driver data is NULL, dropping EJECT\n");
 			return;
 		}
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+			"Hot-removing processor device %s\n",
+			dev_name(&device->dev)));
+		if (acpi_bus_trim(device, 1)) {
+			printk(KERN_ERR "ACPI: Removing device failed!\n");
+			return;
+		}
 		break;
 	default:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,

Signature · 1 line

1.7.6.0

Bjorn Helgaas

2011-09-14 14:14 UTC #1 lore raw

Quoted 19 lines · canquan.shen

We run linux as a guest in Xen environment. When we used the xen tools (xm vcpu-set <n>) to hot add and remove vcpu to and from the guest, we encountered the failure on vcpu removal. We found the reason is that it didn't go to really remove cpu in the cpu removal code path.
This patch adds acpi_bus_trim in acpi_process_hotplug_notify to fix this issue. With this patch, it works fine for us.
Signed-off-by Shen canquan <[email protected]>
---
drivers/acpi/processor_driver.c | 7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
drivers/acpi/processor_driver.c +0 -0
index a4e0f1b..0856ef8 100644

drivers/acpi/processor_driver.c static void acpi_processor_hotplug_notify(acpi_handle · line 685

Quoted 9 lines

drivers/acpi/processor_driver.c +5 -0

@@ -677,6 +677,13 @@ static void acpi_processor_hotplug_notify(acpi_handle
 handle,
                                    "Driver data is NULL, dropping EJECT\n");
                        return;
                }
+               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+                       "Hot-removing processor device %s\n",
+                       dev_name(&device->dev)));
+               if (acpi_bus_trim(device, 1)) {
+                       printk(KERN_ERR "ACPI: Removing device failed!\n");

We can do better than that. Nobody ever looks at ACPI_DEBUG_PRINT info.

    u32 id;
    ...
    id = pr->id;
    if (acpi_bus_trim(device, 1))
        printk(KERN_ERR PREFIX "Failed to remove CPU %d\n", id);

(No "return" needed here. In fact, the "return" at the bottom of acpi_processor_hotplug_notify() is also superfluous. You could remove it at the same time.)
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canquan.shen

author

2011-09-15 01:36 UTC #2 lore raw

Quoted 38 lines · Bjorn Helgaas

Quoted 19 lines · canquan.shen
We run linux as a guest in Xen environment. When we used the xen tools (xm vcpu-set<n>) to hot add and remove vcpu to and from the guest, we encountered the failure on vcpu removal. We found the reason is that it didn't go to really remove cpu in the cpu removal code path.
This patch adds acpi_bus_trim in acpi_process_hotplug_notify to fix this issue. With this patch, it works fine for us.
Signed-off-by Shen canquan<[email protected]>
---
  drivers/acpi/processor_driver.c |    7 +++++++
  1 files changed, 7 insertions(+), 0 deletions(-)
drivers/acpi/processor_driver.c +0 -0
index a4e0f1b..0856ef8 100644
drivers/acpi/processor_driver.c static void acpi_processor_hotplug_notify(acpi_handle · line 685
Quoted 9 lines
drivers/acpi/processor_driver.c +5 -0
@@ -677,6 +677,13 @@ static void acpi_processor_hotplug_notify(acpi_handle
 handle,
                                    "Driver data is NULL, dropping EJECT\n");
                        return;
                }
+               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+                       "Hot-removing processor device %s\n",
+                       dev_name(&device->dev)));
+               if (acpi_bus_trim(device, 1)) {
+                       printk(KERN_ERR "ACPI: Removing device failed!\n");
We can do better than that. Nobody ever looks at ACPI_DEBUG_PRINT info.
     u32 id;
     ...
     id = pr->id;
     if (acpi_bus_trim(device, 1))
         printk(KERN_ERR PREFIX "Failed to remove CPU %d\n", id);

Quoted 6 lines

(No "return" needed here. In fact, the "return" at the bottom of acpi_processor_hotplug_notify() is also superfluous. You could remove it at the same time.)
.

Thanks for your suggestion. I will modify it and resend the patch.

--
Canquan.shen