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Subject[PATCH 1/2] xen/acpi: xen memory hotplug minor updates
Date
From aa363f1a4f862fab2f50dfe3ad602bb8dd234709 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Sat, 16 Feb 2013 16:59:03 +0800
Subject: [PATCH 1/2] xen/acpi: xen memory hotplug minor updates

Dan Carpenter found current xen memory hotplug logic
has potential issue: at func acpi_memory_get_device()
*mem_device = acpi_driver_data(device);
while the device may be NULL and then dereference.

At native side, Rafael recently updated acpi_memory_get_device(),
dropping acpi_bus_add, adding lock, and avoiding above issue.

This patch updates xen memory hotplug logic accordingly, removing
redundant logic, adding lock, and avoiding dereference.

Signed-off-by: Liu Jinsong <jinsong.liu@intel.com>
---
drivers/xen/xen-acpi-memhotplug.c | 52 ++++++++++++++++++------------------
1 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/drivers/xen/xen-acpi-memhotplug.c b/drivers/xen/xen-acpi-memhotplug.c
index 853b12d..faef5b3 100644
--- a/drivers/xen/xen-acpi-memhotplug.c
+++ b/drivers/xen/xen-acpi-memhotplug.c
@@ -158,31 +158,17 @@ acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
return 0;
}

-static int
-acpi_memory_get_device(acpi_handle handle,
- struct acpi_memory_device **mem_device)
+static int acpi_memory_get_device(acpi_handle handle,
+ struct acpi_memory_device **mem_device)
{
- acpi_status status;
- acpi_handle phandle;
struct acpi_device *device = NULL;
- struct acpi_device *pdevice = NULL;
- int result;
+ int result = 0;

- if (!acpi_bus_get_device(handle, &device) && device)
- goto end;
+ acpi_scan_lock_acquire();

- status = acpi_get_parent(handle, &phandle);
- if (ACPI_FAILURE(status)) {
- pr_warn(PREFIX "Cannot find acpi parent\n");
- return -EINVAL;
- }
-
- /* Get the parent device */
- result = acpi_bus_get_device(phandle, &pdevice);
- if (result) {
- pr_warn(PREFIX "Cannot get acpi bus device\n");
- return -EINVAL;
- }
+ acpi_bus_get_device(handle, &device);
+ if (device)
+ goto end;

/*
* Now add the notified device. This creates the acpi_device
@@ -190,18 +176,28 @@ acpi_memory_get_device(acpi_handle handle,
*/
result = acpi_bus_scan(handle);
if (result) {
- pr_warn(PREFIX "Cannot add acpi bus\n");
- return -EINVAL;
+ pr_warn(PREFIX "ACPI namespace scan failed\n");
+ result = -EINVAL;
+ goto out;
+ }
+ result = acpi_bus_get_device(handle, &device);
+ if (result) {
+ pr_warn(PREFIX "Missing device object\n");
+ result = -EINVAL;
+ goto out;
}

end:
*mem_device = acpi_driver_data(device);
if (!(*mem_device)) {
- pr_err(PREFIX "Driver data not found\n");
- return -ENODEV;
+ pr_err(PREFIX "driver data not found\n");
+ result = -ENODEV;
+ goto out;
}

- return 0;
+out:
+ acpi_scan_lock_release();
+ return result;
}

static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
@@ -259,12 +255,15 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"\nReceived EJECT REQUEST notification for device\n"));

+ acpi_scan_lock_acquire();
if (acpi_bus_get_device(handle, &device)) {
+ acpi_scan_lock_release();
pr_err(PREFIX "Device doesn't exist\n");
break;
}
mem_device = acpi_driver_data(device);
if (!mem_device) {
+ acpi_scan_lock_release();
pr_err(PREFIX "Driver Data is NULL\n");
break;
}
@@ -274,6 +273,7 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
* acpi_bus_remove if Xen support hotremove in the future
*/
acpi_memory_disable_device(mem_device);
+ acpi_scan_lock_release();
break;

default:
--
1.7.1[unhandled content-type:application/octet-stream]
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