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extcon: Use unique number for the extcon device ID 

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>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
This commit is contained in:
Andy Shevchenko 2023-04-11 14:48:22 +03:00 committed by Chanwoo Choi
parent 566825a31f
commit 7bba9e81a6
2 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/extcon/extcon.c
View File

@ -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)
@ -1275,8 +1276,14 @@ int extcon_dev_register(struct extcon_dev *edev)
"extcon device name is null\n");
return -EINVAL;
}
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)
@ -1339,6 +1346,7 @@ err_alloc_muex:
if (edev->max_supported)
kfree(edev->cables);
err_alloc_cables:
ida_free(&extcon_dev_ids, edev->id);
return ret;
}
@ -1367,6 +1375,8 @@ 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) {

2
drivers/extcon/extcon.h
View File

@ -20,6 +20,7 @@
* {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
@ -46,6 +47,7 @@ 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;