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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-02-13 17:36:47 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-02-13 17:36:47 +0400
commit3757b94802fb65d8f696597a74053cf21738da0b (patch)
tree78a3a00dbd82fab5e30a46699f83a3e492604e86 /drivers/acpi/acpi_memhotplug.c
parent64fd7401c5e4cf7c64452ecd9b700a55a5ebea50 (diff)
downloadlinux-3757b94802fb65d8f696597a74053cf21738da0b.tar.xz
ACPI / hotplug: Fix concurrency issues and memory leaks
This changeset is aimed at fixing a few different but related problems in the ACPI hotplug infrastructure. First of all, since notify handlers may be run in parallel with acpi_bus_scan(), acpi_bus_trim() and acpi_bus_hot_remove_device() and some of them are installed for ACPI handles that have no struct acpi_device objects attached (i.e. before those objects are created), those notify handlers have to take acpi_scan_lock to prevent races from taking place (e.g. a struct acpi_device is found to be present for the given ACPI handle, but right after that it is removed by acpi_bus_trim() running in parallel to the given notify handler). Moreover, since some of them call acpi_bus_scan() and acpi_bus_trim(), this leads to the conclusion that acpi_scan_lock should be acquired by the callers of these two funtions rather by these functions themselves. For these reasons, make all notify handlers that can handle device addition and eject events take acpi_scan_lock and remove the acpi_scan_lock locking from acpi_bus_scan() and acpi_bus_trim(). Accordingly, update all of their users to make sure that they are always called under acpi_scan_lock. Furthermore, since eject operations are carried out asynchronously with respect to the notify events that trigger them, with the help of acpi_bus_hot_remove_device(), even if notify handlers take the ACPI scan lock, it still is possible that, for example, acpi_bus_trim() will run between acpi_bus_hot_remove_device() and the notify handler that scheduled its execution and that acpi_bus_trim() will remove the device node passed to acpi_bus_hot_remove_device() for ejection. In that case, the struct acpi_device object obtained by acpi_bus_hot_remove_device() will be invalid and not-so-funny things will ensue. To protect agaist that, make the users of acpi_bus_hot_remove_device() run get_device() on ACPI device node objects that are about to be passed to it and make acpi_bus_hot_remove_device() run put_device() on them and check if their ACPI handles are not NULL (make acpi_device_unregister() clear the device nodes' ACPI handles for that check to work). Finally, observe that acpi_os_hotplug_execute() actually can fail, in which case its caller ought to free memory allocated for the context object to prevent leaks from happening. It also needs to run put_device() on the device node that it ran get_device() on previously in that case. Modify the code accordingly. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Yinghai Lu <yinghai@kernel.org>
Diffstat (limited to 'drivers/acpi/acpi_memhotplug.c')
-rw-r--r--drivers/acpi/acpi_memhotplug.c56
1 files changed, 37 insertions, 19 deletions
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 94c823b25138..034d3e72aa92 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -153,14 +153,16 @@ 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)
{
struct acpi_device *device = NULL;
- int result;
+ int result = 0;
- if (!acpi_bus_get_device(handle, &device) && device)
+ acpi_scan_lock_acquire();
+
+ acpi_bus_get_device(handle, &device);
+ if (device)
goto end;
/*
@@ -169,23 +171,28 @@ acpi_memory_get_device(acpi_handle handle,
*/
result = acpi_bus_scan(handle);
if (result) {
- acpi_handle_warn(handle, "Cannot add acpi bus\n");
- return -EINVAL;
+ acpi_handle_warn(handle, "ACPI namespace scan failed\n");
+ result = -EINVAL;
+ goto out;
}
result = acpi_bus_get_device(handle, &device);
if (result) {
acpi_handle_warn(handle, "Missing device object\n");
- return -EINVAL;
+ result = -EINVAL;
+ goto out;
}
- end:
+ end:
*mem_device = acpi_driver_data(device);
if (!(*mem_device)) {
dev_err(&device->dev, "driver data not found\n");
- return -ENODEV;
+ 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)
@@ -305,6 +312,7 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
struct acpi_device *device;
struct acpi_eject_event *ej_event = NULL;
u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */
+ acpi_status status;
switch (event) {
case ACPI_NOTIFY_BUS_CHECK:
@@ -327,29 +335,40 @@ 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"));
+ status = AE_ERROR;
+ acpi_scan_lock_acquire();
+
if (acpi_bus_get_device(handle, &device)) {
acpi_handle_err(handle, "Device doesn't exist\n");
- break;
+ goto unlock;
}
mem_device = acpi_driver_data(device);
if (!mem_device) {
acpi_handle_err(handle, "Driver Data is NULL\n");
- break;
+ goto unlock;
}
ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
if (!ej_event) {
pr_err(PREFIX "No memory, dropping EJECT\n");
- break;
+ goto unlock;
}
+ get_device(&device->dev);
ej_event->device = device;
ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
- acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
- (void *)ej_event);
+ /* The eject is carried out asynchronously. */
+ status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
+ ej_event);
+ if (ACPI_FAILURE(status)) {
+ put_device(&device->dev);
+ kfree(ej_event);
+ }
- /* eject is performed asynchronously */
- return;
+ unlock:
+ acpi_scan_lock_release();
+ if (ACPI_SUCCESS(status))
+ return;
default:
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Unsupported event [0x%x]\n", event));
@@ -360,7 +379,6 @@ static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
/* Inform firmware that the hotplug operation has completed */
(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
- return;
}
static void acpi_memory_device_free(struct acpi_memory_device *mem_device)