5.6-stable patches

added patches:
	i2c-dev-fix-the-race-between-the-release-of-i2c_dev-and-cdev.patch

diff --git a/queue-5.6/i2c-dev-fix-the-race-between-the-release-of-i2c_dev-and-cdev.patch b/queue-5.6/i2c-dev-fix-the-race-between-the-release-of-i2c_dev-and-cdev.patch
new file mode 100644 (file)
index 0000000..30ee0ab
--- /dev/null
+++ b/queue-5.6/i2c-dev-fix-the-race-between-the-release-of-i2c_dev-and-cdev.patch
@@ -0,0 +1,184 @@
+From 1413ef638abae4ab5621901cf4d8ef08a4a48ba6 Mon Sep 17 00:00:00 2001
+From: Kevin Hao <haokexin@gmail.com>
+Date: Fri, 11 Oct 2019 23:00:14 +0800
+Subject: i2c: dev: Fix the race between the release of i2c_dev and cdev
+
+From: Kevin Hao <haokexin@gmail.com>
+
+commit 1413ef638abae4ab5621901cf4d8ef08a4a48ba6 upstream.
+
+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>
+Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/i2c/i2c-dev.c |   48 ++++++++++++++++++++++++++----------------------
+ 1 file changed, 26 insertions(+), 22 deletions(-)
+
+--- 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(
+       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 i2cd
+ 
+ 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
+ 
+       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
+       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;