[v2,3/5] extcon: Use unique number for the extcon device ID
Commit Message
The use of atomic variable is still racy when we do not control which
device has been unregistered and there is a (theoretical) possibility
of the overflow that may cause a duplicate extcon device ID number
to be allocated next time a device is registered.
Replace above mentioned approach by using IDA framework.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Bumwoo Lee <bw365.lee@samsung.com>
---
drivers/extcon/extcon.c | 15 ++++++++++++---
drivers/extcon/extcon.h | 2 ++
2 files changed, 14 insertions(+), 3 deletions(-)
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/types.h>
+#include <linux/idr.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/fs.h>
@@ -238,6 +239,7 @@ struct extcon_cable {
static struct class *extcon_class;
+static DEFINE_IDA(extcon_dev_ids);
static LIST_HEAD(extcon_dev_list);
static DEFINE_MUTEX(extcon_dev_list_lock);
@@ -1248,7 +1250,6 @@ static int extcon_alloc_groups(struct extcon_dev *edev)
int extcon_dev_register(struct extcon_dev *edev)
{
int ret, index = 0;
- static atomic_t edev_no = ATOMIC_INIT(-1);
ret = create_extcon_class();
if (ret < 0)
@@ -1269,8 +1270,13 @@ int extcon_dev_register(struct extcon_dev *edev)
edev->dev.class = extcon_class;
edev->dev.release = extcon_dev_release;
- dev_set_name(&edev->dev, "extcon%lu",
- (unsigned long)atomic_inc_return(&edev_no));
+ ret = ida_alloc(&extcon_dev_ids, GFP_KERNEL);
+ if (ret < 0)
+ return ret;
+
+ edev->id = ret;
+
+ dev_set_name(&edev->dev, "extcon%d", edev->id);
ret = extcon_alloc_cables(edev);
if (ret < 0)
@@ -1333,6 +1339,7 @@ int extcon_dev_register(struct extcon_dev *edev)
if (edev->max_supported)
kfree(edev->cables);
err_alloc_cables:
+ ida_free(&extcon_dev_ids, edev->id);
return ret;
}
@@ -1361,6 +1368,8 @@ void extcon_dev_unregister(struct extcon_dev *edev)
return;
}
+ ida_free(&extcon_dev_ids, edev->id);
+
device_unregister(&edev->dev);
if (edev->mutually_exclusive && edev->max_supported) {
@@ -18,6 +18,7 @@
* {0x3, 0x6, 0x5, 0}. If it is {0xFFFFFFFF, 0}, there
* can be no simultaneous connections.
* @dev: Device of this extcon.
+ * @id: Unique device ID of this extcon.
* @state: Attach/detach state of this extcon. Do not provide at
* register-time.
* @nh_all: Notifier for the state change events for all supported
@@ -43,6 +44,7 @@ struct extcon_dev {
/* Internal data. Please do not set. */
struct device dev;
+ unsigned int id;
struct raw_notifier_head nh_all;
struct raw_notifier_head *nh;
struct list_head entry;