At 10/27/2012 01:14 AM, Toshi Kani Wrote:

On Fri, 2012-10-26 at 18:31 +0800, wency@cn.fujitsu.com wrote:

quoted

From: Yasuaki Ishimatsu <redacted>

The memory device can be removed by 2 ways:
1. send eject request by SCI
2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject

In the 1st case, acpi_memory_disable_device() will be called.
In the 2nd case, acpi_memory_device_remove() will be called.

Hi Yasuaki, Wen,

Why do you need to have separate code design & implementation for the
two cases?  In other words, can the 1st case simply use the same code
path of the 2nd case, just like I did for the CPU hot-remove patch
below?  It will simplify the code and make the memory notify handler
more consistent with other handlers.
https://lkml.org/lkml/2012/10/19/456

Yes, the 1st case can simply reuse the same code of the 2nd case.
It is another issue. The memory is not offlined and removed in 2nd
case. This patchset tries to fix this problem. After doing this,
we can merge the codes for the two cases.

But there is some bug in the code for 2nd case:
If offlining memory failed, we don't know such error in 2nd case, and
the kernel will in a dangerous state: the memory device is poweroffed
but the kernel is using it.

We should fix this bug before merging them.

Thanks
Wen Congyang

Thanks,
-Toshi

quoted

acpi_memory_device_remove() will also be called when we unbind the
memory device from the driver acpi_memhotplug or a driver initialization
fails.

acpi_memory_disable_device() has already implemented a code which
offlines memory and releases acpi_memory_info struct. But
acpi_memory_device_remove() has not implemented it yet.

So the patch move offlining memory and releasing acpi_memory_info struct
codes to a new function acpi_memory_remove_memory(). And it is used by both
acpi_memory_device_remove() and acpi_memory_disable_device().

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <redacted>
CC: Len Brown <redacted>
CC: Christoph Lameter <redacted>
Cc: Minchan Kim <redacted>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <redacted>
Signed-off-by: Yasuaki Ishimatsu <redacted>
Signed-off-by: Wen Congyang <redacted>
---
 drivers/acpi/acpi_memhotplug.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 666dac6..92c973a 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c

@@ -316,16 +316,11 @@ static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
 	return 0;
 }
 
-static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
+static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
 	int result;
 	struct acpi_memory_info *info, *n;
 
-
-	/*
-	 * Ask the VM to offline this memory range.
-	 * Note: Assume that this function returns zero on success
-	 */
 	mutex_lock(&mem_device->list_lock);
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (info->enabled) {

@@ -333,10 +328,27 @@ static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
 			if (result)
 				return result;
 		}
+
+		list_del(&info->list);
 		kfree(info);
 	}
 	mutex_unlock(&mem_device->list_lock);
 
+	return 0;
+}
+
+static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
+{
+	int result;
+
+	/*
+	 * Ask the VM to offline this memory range.
+	 * Note: Assume that this function returns zero on success
+	 */
+	result = acpi_memory_remove_memory(mem_device);
+	if (result)
+		return result;
+
 	/* Power-off and eject the device */
 	result = acpi_memory_powerdown_device(mem_device);
 	if (result) {

@@ -487,12 +499,17 @@ static int acpi_memory_device_add(struct acpi_device *device)
 static int acpi_memory_device_remove(struct acpi_device *device, int type)
 {
 	struct acpi_memory_device *mem_device = NULL;
-
+	int result;
 
 	if (!device || !acpi_driver_data(device))
 		return -EINVAL;
 
 	mem_device = acpi_driver_data(device);
+
+	result = acpi_memory_remove_memory(mem_device);
+	if (result)
+		return result;
+
 	kfree(mem_device);
 
 	return 0;

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