[PATCH 18/24][Update] ACPI / hotplug: Fix potential race in acpi_bus_notify()
From: Rafael J. Wysocki
There is a slight possibility for the ACPI device object pointed to
by adev in acpi_hotplug_notify_cb() to become invalid between the
acpi_bus_get_device() that it comes from and the subsequent dereference
of that pointer under get_device(). Namely, if acpi_scan_drop_device()
runs in parallel with acpi_hotplug_notify_cb(), acpi_device_del_work_fn()
queued up by it may delete the device object in question right after
a successful execution of acpi_bus_get_device() in acpi_bus_notify().
An analogous problem is present in acpi_bus_notify() where the device
pointer coming from acpi_bus_get_device() may become invalid before
it subsequent dereference in the "if" block.
To prevent that from happening, introduce a new function,
acpi_bus_get_acpi_device(), working analogously to acpi_bus_get_device()
except that it will grab a reference to the ACPI device object returned
by it and it will do that under the ACPICA's namespace mutex. Then,
make both acpi_hotplug_notify_cb() and acpi_bus_notify() use
acpi_bus_get_acpi_device() instead of acpi_bus_get_device() so as to
ensure that the pointers used by them will not become stale at one
point.
In addition to that, introduce acpi_bus_put_acpi_device() as a wrapper
around put_device() to be used along with acpi_bus_get_acpi_device()
and make the (new) users of the latter use acpi_bus_put_acpi_device()
too.
Signed-off-by: Rafael J. Wysocki
---
drivers/acpi/bus.c |6 --
drivers/acpi/scan.c | 42 ++
include/acpi/acpi_bus.h |2 ++
3 files changed, 40 insertions(+), 10 deletions(-)
Index: linux-pm/drivers/acpi/scan.c
===
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -476,7 +476,7 @@ static void acpi_device_hotplug(void *da
out:
acpi_evaluate_hotplug_ost(adev->handle, src, ost_code, NULL);
- put_device(>dev);
+ acpi_bus_put_acpi_device(adev);
mutex_unlock(_scan_lock);
unlock_device_hotplug();
}
@@ -488,9 +488,6 @@ static void acpi_hotplug_notify_cb(acpi_
struct acpi_device *adev;
acpi_status status;
- if (acpi_bus_get_device(handle, ))
- goto err_out;
-
switch (type) {
case ACPI_NOTIFY_BUS_CHECK:
acpi_handle_debug(handle, "ACPI_NOTIFY_BUS_CHECK event\n");
@@ -512,12 +509,15 @@ static void acpi_hotplug_notify_cb(acpi_
/* non-hotplug event; possibly handled by other handler */
return;
}
- get_device(>dev);
+ adev = acpi_bus_get_acpi_device(handle);
+ if (!adev)
+ goto err_out;
+
status = acpi_hotplug_execute(acpi_device_hotplug, adev, type);
if (ACPI_SUCCESS(status))
return;
- put_device(>dev);
+ acpi_bus_put_acpi_device(adev);
err_out:
acpi_evaluate_hotplug_ost(handle, type, ost_code, NULL);
@@ -1112,14 +1112,16 @@ static void acpi_scan_drop_device(acpi_h
mutex_unlock(_device_del_lock);
}
-int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
+static int acpi_get_device_data(acpi_handle handle, struct acpi_device
**device,
+ void (*callback)(void *))
{
acpi_status status;
if (!device)
return -EINVAL;
- status = acpi_get_data(handle, acpi_scan_drop_device, (void **)device);
+ status = acpi_get_data_full(handle, acpi_scan_drop_device,
+ (void **)device, callback);
if (ACPI_FAILURE(status) || !*device) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No context for object [%p]\n",
handle));
@@ -1127,8 +1129,32 @@ int acpi_bus_get_device(acpi_handle hand
}
return 0;
}
+
+int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
+{
+ return acpi_get_device_data(handle, device, NULL);
+}
EXPORT_SYMBOL(acpi_bus_get_device);
+static void get_acpi_device(void *dev)
+{
+ if (dev)
+ get_device(&((struct acpi_device *)dev)->dev);
+}
+
+struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
+{
+ struct acpi_device *adev = NULL;
+
+ acpi_get_device_data(handle, , get_acpi_device);
+ return adev;
+}
+
+void acpi_bus_put_acpi_device(struct acpi_device *adev)
+{
+ put_device(>dev);
+}
+
int acpi_device_add(struct acpi_device *device,
void (*release)(struct device *))
{
Index: linux-pm/drivers/acpi/bus.c
===
--- linux-pm.orig/drivers/acpi/bus.c
+++ linux-pm/drivers/acpi/bus.c
@@ -340,7 +340,7 @@ static void acpi_bus_osc_support(void)
*/
static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
{
- struct acpi_device *device = NULL;
+ struct acpi_device *device;
struct
[PATCH 18/24][Update] ACPI / hotplug: Fix potential race in acpi_bus_notify()
From: Rafael J. Wysocki rafael.j.wyso...@intel.com
There is a slight possibility for the ACPI device object pointed to
by adev in acpi_hotplug_notify_cb() to become invalid between the
acpi_bus_get_device() that it comes from and the subsequent dereference
of that pointer under get_device(). Namely, if acpi_scan_drop_device()
runs in parallel with acpi_hotplug_notify_cb(), acpi_device_del_work_fn()
queued up by it may delete the device object in question right after
a successful execution of acpi_bus_get_device() in acpi_bus_notify().
An analogous problem is present in acpi_bus_notify() where the device
pointer coming from acpi_bus_get_device() may become invalid before
it subsequent dereference in the if block.
To prevent that from happening, introduce a new function,
acpi_bus_get_acpi_device(), working analogously to acpi_bus_get_device()
except that it will grab a reference to the ACPI device object returned
by it and it will do that under the ACPICA's namespace mutex. Then,
make both acpi_hotplug_notify_cb() and acpi_bus_notify() use
acpi_bus_get_acpi_device() instead of acpi_bus_get_device() so as to
ensure that the pointers used by them will not become stale at one
point.
In addition to that, introduce acpi_bus_put_acpi_device() as a wrapper
around put_device() to be used along with acpi_bus_get_acpi_device()
and make the (new) users of the latter use acpi_bus_put_acpi_device()
too.
Signed-off-by: Rafael J. Wysocki rafael.j.wyso...@intel.com
---
drivers/acpi/bus.c |6 --
drivers/acpi/scan.c | 42 ++
include/acpi/acpi_bus.h |2 ++
3 files changed, 40 insertions(+), 10 deletions(-)
Index: linux-pm/drivers/acpi/scan.c
===
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -476,7 +476,7 @@ static void acpi_device_hotplug(void *da
out:
acpi_evaluate_hotplug_ost(adev-handle, src, ost_code, NULL);
- put_device(adev-dev);
+ acpi_bus_put_acpi_device(adev);
mutex_unlock(acpi_scan_lock);
unlock_device_hotplug();
}
@@ -488,9 +488,6 @@ static void acpi_hotplug_notify_cb(acpi_
struct acpi_device *adev;
acpi_status status;
- if (acpi_bus_get_device(handle, adev))
- goto err_out;
-
switch (type) {
case ACPI_NOTIFY_BUS_CHECK:
acpi_handle_debug(handle, ACPI_NOTIFY_BUS_CHECK event\n);
@@ -512,12 +509,15 @@ static void acpi_hotplug_notify_cb(acpi_
/* non-hotplug event; possibly handled by other handler */
return;
}
- get_device(adev-dev);
+ adev = acpi_bus_get_acpi_device(handle);
+ if (!adev)
+ goto err_out;
+
status = acpi_hotplug_execute(acpi_device_hotplug, adev, type);
if (ACPI_SUCCESS(status))
return;
- put_device(adev-dev);
+ acpi_bus_put_acpi_device(adev);
err_out:
acpi_evaluate_hotplug_ost(handle, type, ost_code, NULL);
@@ -1112,14 +1112,16 @@ static void acpi_scan_drop_device(acpi_h
mutex_unlock(acpi_device_del_lock);
}
-int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
+static int acpi_get_device_data(acpi_handle handle, struct acpi_device
**device,
+ void (*callback)(void *))
{
acpi_status status;
if (!device)
return -EINVAL;
- status = acpi_get_data(handle, acpi_scan_drop_device, (void **)device);
+ status = acpi_get_data_full(handle, acpi_scan_drop_device,
+ (void **)device, callback);
if (ACPI_FAILURE(status) || !*device) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, No context for object [%p]\n,
handle));
@@ -1127,8 +1129,32 @@ int acpi_bus_get_device(acpi_handle hand
}
return 0;
}
+
+int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
+{
+ return acpi_get_device_data(handle, device, NULL);
+}
EXPORT_SYMBOL(acpi_bus_get_device);
+static void get_acpi_device(void *dev)
+{
+ if (dev)
+ get_device(((struct acpi_device *)dev)-dev);
+}
+
+struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
+{
+ struct acpi_device *adev = NULL;
+
+ acpi_get_device_data(handle, adev, get_acpi_device);
+ return adev;
+}
+
+void acpi_bus_put_acpi_device(struct acpi_device *adev)
+{
+ put_device(adev-dev);
+}
+
int acpi_device_add(struct acpi_device *device,
void (*release)(struct device *))
{
Index: linux-pm/drivers/acpi/bus.c
===
--- linux-pm.orig/drivers/acpi/bus.c
+++ linux-pm/drivers/acpi/bus.c
@@ -340,7 +340,7 @@ static void acpi_bus_osc_support(void)
*/
static void acpi_bus_notify(acpi_handle handle, u32 type, void *data)
{
- struct acpi_device
