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authorKevin Hao <haokexin@gmail.com>2019-10-11 18:00:14 +0300
committerWolfram Sang <wsa@the-dreams.de>2020-03-20 20:34:29 +0300
commit1413ef638abae4ab5621901cf4d8ef08a4a48ba6 (patch)
tree9cb9cb173bb04629e5c30ec8f06fbdc488b54ecc /drivers/i2c
parent383c67cda2fb394df6bf4082c11aa69b8b120b92 (diff)
downloadlinux-1413ef638abae4ab5621901cf4d8ef08a4a48ba6.tar.xz
i2c: dev: Fix the race between the release of i2c_dev and cdev
The struct cdev is embedded in the struct i2c_dev. In the current code, we would free the i2c_dev struct directly in put_i2c_dev(), but the cdev is manged by a kobject, and the release of it is not predictable. So it is very possible that the i2c_dev is freed before the cdev is entirely released. We can easily get the following call trace with CONFIG_DEBUG_KOBJECT_RELEASE and CONFIG_DEBUG_OBJECTS_TIMERS enabled. ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x38 WARNING: CPU: 19 PID: 1 at lib/debugobjects.c:325 debug_print_object+0xb0/0xf0 Modules linked in: CPU: 19 PID: 1 Comm: swapper/0 Tainted: G W 5.2.20-yocto-standard+ #120 Hardware name: Marvell OcteonTX CN96XX board (DT) pstate: 80c00089 (Nzcv daIf +PAN +UAO) pc : debug_print_object+0xb0/0xf0 lr : debug_print_object+0xb0/0xf0 sp : ffff00001292f7d0 x29: ffff00001292f7d0 x28: ffff800b82151788 x27: 0000000000000001 x26: ffff800b892c0000 x25: ffff0000124a2558 x24: 0000000000000000 x23: ffff00001107a1d8 x22: ffff0000116b5088 x21: ffff800bdc6afca8 x20: ffff000012471ae8 x19: ffff00001168f2c8 x18: 0000000000000010 x17: 00000000fd6f304b x16: 00000000ee79de43 x15: ffff800bc0e80568 x14: 79616c6564203a74 x13: 6e6968207473696c x12: 5f72656d6974203a x11: ffff0000113f0018 x10: 0000000000000000 x9 : 000000000000001f x8 : 0000000000000000 x7 : ffff0000101294cc x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000001 x3 : 00000000ffffffff x2 : 0000000000000000 x1 : 387fc15c8ec0f200 x0 : 0000000000000000 Call trace: debug_print_object+0xb0/0xf0 __debug_check_no_obj_freed+0x19c/0x228 debug_check_no_obj_freed+0x1c/0x28 kfree+0x250/0x440 put_i2c_dev+0x68/0x78 i2cdev_detach_adapter+0x60/0xc8 i2cdev_notifier_call+0x3c/0x70 notifier_call_chain+0x8c/0xe8 blocking_notifier_call_chain+0x64/0x88 device_del+0x74/0x380 device_unregister+0x54/0x78 i2c_del_adapter+0x278/0x2d0 unittest_i2c_bus_remove+0x3c/0x80 platform_drv_remove+0x30/0x50 device_release_driver_internal+0xf4/0x1c0 driver_detach+0x58/0xa0 bus_remove_driver+0x84/0xd8 driver_unregister+0x34/0x60 platform_driver_unregister+0x20/0x30 of_unittest_overlay+0x8d4/0xbe0 of_unittest+0xae8/0xb3c do_one_initcall+0xac/0x450 do_initcall_level+0x208/0x224 kernel_init_freeable+0x2d8/0x36c kernel_init+0x18/0x108 ret_from_fork+0x10/0x1c irq event stamp: 3934661 hardirqs last enabled at (3934661): [<ffff00001009fa04>] debug_exception_exit+0x4c/0x58 hardirqs last disabled at (3934660): [<ffff00001009fb14>] debug_exception_enter+0xa4/0xe0 softirqs last enabled at (3934654): [<ffff000010081d94>] __do_softirq+0x46c/0x628 softirqs last disabled at (3934649): [<ffff0000100b4a1c>] irq_exit+0x104/0x118 This is a common issue when using cdev embedded in a struct. Fortunately, we already have a mechanism to solve this kind of issue. Please see commit 233ed09d7fda ("chardev: add helper function to register char devs with a struct device") for more detail. In this patch, we choose to embed the struct device into the i2c_dev, and use the API provided by the commit 233ed09d7fda to make sure that the release of i2c_dev and cdev are in sequence. Signed-off-by: Kevin Hao <haokexin@gmail.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/i2c-dev.c48
1 files changed, 26 insertions, 22 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index ffd381e4afd2..da020acc9bbd 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -40,7 +40,7 @@
struct i2c_dev {
struct list_head list;
struct i2c_adapter *adap;
- struct device *dev;
+ struct device dev;
struct cdev cdev;
};
@@ -84,12 +84,14 @@ static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
return i2c_dev;
}
-static void put_i2c_dev(struct i2c_dev *i2c_dev)
+static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
{
spin_lock(&i2c_dev_list_lock);
list_del(&i2c_dev->list);
spin_unlock(&i2c_dev_list_lock);
- kfree(i2c_dev);
+ if (del_cdev)
+ cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
+ put_device(&i2c_dev->dev);
}
static ssize_t name_show(struct device *dev,
@@ -628,6 +630,14 @@ static const struct file_operations i2cdev_fops = {
static struct class *i2c_dev_class;
+static void i2cdev_dev_release(struct device *dev)
+{
+ struct i2c_dev *i2c_dev;
+
+ i2c_dev = container_of(dev, struct i2c_dev, dev);
+ kfree(i2c_dev);
+}
+
static int i2cdev_attach_adapter(struct device *dev, void *dummy)
{
struct i2c_adapter *adap;
@@ -644,27 +654,23 @@ static int i2cdev_attach_adapter(struct device *dev, void *dummy)
cdev_init(&i2c_dev->cdev, &i2cdev_fops);
i2c_dev->cdev.owner = THIS_MODULE;
- res = cdev_add(&i2c_dev->cdev, MKDEV(I2C_MAJOR, adap->nr), 1);
- if (res)
- goto error_cdev;
-
- /* register this i2c device with the driver core */
- i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
- MKDEV(I2C_MAJOR, adap->nr), NULL,
- "i2c-%d", adap->nr);
- if (IS_ERR(i2c_dev->dev)) {
- res = PTR_ERR(i2c_dev->dev);
- goto error;
+
+ device_initialize(&i2c_dev->dev);
+ i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
+ i2c_dev->dev.class = i2c_dev_class;
+ i2c_dev->dev.parent = &adap->dev;
+ i2c_dev->dev.release = i2cdev_dev_release;
+ dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
+
+ res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
+ if (res) {
+ put_i2c_dev(i2c_dev, false);
+ return res;
}
pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
adap->name, adap->nr);
return 0;
-error:
- cdev_del(&i2c_dev->cdev);
-error_cdev:
- put_i2c_dev(i2c_dev);
- return res;
}
static int i2cdev_detach_adapter(struct device *dev, void *dummy)
@@ -680,9 +686,7 @@ static int i2cdev_detach_adapter(struct device *dev, void *dummy)
if (!i2c_dev) /* attach_adapter must have failed */
return 0;
- cdev_del(&i2c_dev->cdev);
- put_i2c_dev(i2c_dev);
- device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
+ put_i2c_dev(i2c_dev, true);
pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
return 0;