+++ /dev/null
-From 1cf1b24c844a037da38e6096a865bcab75aa05eb Mon Sep 17 00:00:00 2001
-From: Kevin Hao <haokexin@gmail.com>
-Date: Tue, 8 Oct 2019 19:29:34 +0800
-Subject: watchdog: Fix the race between the release of watchdog_core_data and cdev
-
-From: Kevin Hao <haokexin@gmail.com>
-
-commit 72139dfa2464e43957d330266994740bb7be2535 upstream.
-
-The struct cdev is embedded in the struct watchdog_core_data. In the
-current code, we manage the watchdog_core_data with a kref, but the
-cdev is manged by a kobject. There is no any relationship between
-this kref and kobject. So it is possible that the watchdog_core_data 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: 23 PID: 1028 at lib/debugobjects.c:481 debug_print_object+0xb0/0xf0
- Modules linked in: softdog(-) deflate ctr twofish_generic twofish_common camellia_generic serpent_generic blowfish_generic blowfish_common cast5_generic cast_common cmac xcbc af_key sch_fq_codel openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
- CPU: 23 PID: 1028 Comm: modprobe Not tainted 5.3.0-next-20190924-yoctodev-standard+ #180
- Hardware name: Marvell OcteonTX CN96XX board (DT)
- pstate: 00400009 (nzcv daif +PAN -UAO)
- pc : debug_print_object+0xb0/0xf0
- lr : debug_print_object+0xb0/0xf0
- sp : ffff80001cbcfc70
- x29: ffff80001cbcfc70 x28: ffff800010ea2128
- x27: ffff800010bad000 x26: 0000000000000000
- x25: ffff80001103c640 x24: ffff80001107b268
- x23: ffff800010bad9e8 x22: ffff800010ea2128
- x21: ffff000bc2c62af8 x20: ffff80001103c600
- x19: ffff800010e867d8 x18: 0000000000000060
- x17: 0000000000000000 x16: 0000000000000000
- x15: ffff000bd7240470 x14: 6e6968207473696c
- x13: 5f72656d6974203a x12: 6570797420746365
- x11: 6a626f2029302065 x10: 7461747320657669
- x9 : 7463612820657669 x8 : 3378302f3078302b
- x7 : 0000000000001d7a x6 : ffff800010fd5889
- x5 : 0000000000000000 x4 : 0000000000000000
- x3 : 0000000000000000 x2 : ffff000bff948548
- x1 : 276a1c9e1edc2300 x0 : 0000000000000000
- Call trace:
- debug_print_object+0xb0/0xf0
- debug_check_no_obj_freed+0x1e8/0x210
- kfree+0x1b8/0x368
- watchdog_cdev_unregister+0x88/0xc8
- watchdog_dev_unregister+0x38/0x48
- watchdog_unregister_device+0xa8/0x100
- softdog_exit+0x18/0xfec4 [softdog]
- __arm64_sys_delete_module+0x174/0x200
- el0_svc_handler+0xd0/0x1c8
- el0_svc+0x8/0xc
-
-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
-watchdog_core_data, and use the API provided by the commit 233ed09d7fda
-to make sure that the release of watchdog_core_data and cdev are
-in sequence.
-
-Signed-off-by: Kevin Hao <haokexin@gmail.com>
-Reviewed-by: Guenter Roeck <linux@roeck-us.net>
-Link: https://lore.kernel.org/r/20191008112934.29669-1-haokexin@gmail.com
-Signed-off-by: Guenter Roeck <linux@roeck-us.net>
-Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
-[bwh: Backported to 4.9:
- - There's no reboot notifier here
- - Adjust context]
-Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- drivers/watchdog/watchdog_dev.c | 67 +++++++++++++++++-----------------------
- 1 file changed, 30 insertions(+), 37 deletions(-)
-
---- a/drivers/watchdog/watchdog_dev.c
-+++ b/drivers/watchdog/watchdog_dev.c
-@@ -38,7 +38,6 @@
- #include <linux/init.h> /* For __init/__exit/... */
- #include <linux/jiffies.h> /* For timeout functions */
- #include <linux/kernel.h> /* For printk/panic/... */
--#include <linux/kref.h> /* For data references */
- #include <linux/miscdevice.h> /* For handling misc devices */
- #include <linux/module.h> /* For module stuff/... */
- #include <linux/mutex.h> /* For mutexes */
-@@ -53,14 +52,14 @@
-
- /*
- * struct watchdog_core_data - watchdog core internal data
-- * @kref: Reference count.
-+ * @dev: The watchdog's internal device
- * @cdev: The watchdog's Character device.
- * @wdd: Pointer to watchdog device.
- * @lock: Lock for watchdog core.
- * @status: Watchdog core internal status bits.
- */
- struct watchdog_core_data {
-- struct kref kref;
-+ struct device dev;
- struct cdev cdev;
- struct watchdog_device *wdd;
- struct mutex lock;
-@@ -794,7 +793,7 @@ static int watchdog_open(struct inode *i
- file->private_data = wd_data;
-
- if (!hw_running)
-- kref_get(&wd_data->kref);
-+ get_device(&wd_data->dev);
-
- /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
- return nonseekable_open(inode, file);
-@@ -806,11 +805,11 @@ out_clear:
- return err;
- }
-
--static void watchdog_core_data_release(struct kref *kref)
-+static void watchdog_core_data_release(struct device *dev)
- {
- struct watchdog_core_data *wd_data;
-
-- wd_data = container_of(kref, struct watchdog_core_data, kref);
-+ wd_data = container_of(dev, struct watchdog_core_data, dev);
-
- kfree(wd_data);
- }
-@@ -870,7 +869,7 @@ done:
- */
- if (!running) {
- module_put(wd_data->cdev.owner);
-- kref_put(&wd_data->kref, watchdog_core_data_release);
-+ put_device(&wd_data->dev);
- }
- return 0;
- }
-@@ -889,17 +888,22 @@ static struct miscdevice watchdog_miscde
- .fops = &watchdog_fops,
- };
-
-+static struct class watchdog_class = {
-+ .name = "watchdog",
-+ .owner = THIS_MODULE,
-+ .dev_groups = wdt_groups,
-+};
-+
- /*
- * watchdog_cdev_register: register watchdog character device
- * @wdd: watchdog device
-- * @devno: character device number
- *
- * Register a watchdog character device including handling the legacy
- * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
- * thus we set it up like that.
- */
-
--static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
-+static int watchdog_cdev_register(struct watchdog_device *wdd)
- {
- struct watchdog_core_data *wd_data;
- int err;
-@@ -907,7 +911,6 @@ static int watchdog_cdev_register(struct
- wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
- if (!wd_data)
- return -ENOMEM;
-- kref_init(&wd_data->kref);
- mutex_init(&wd_data->lock);
-
- wd_data->wdd = wdd;
-@@ -934,23 +937,33 @@ static int watchdog_cdev_register(struct
- }
- }
-
-+ device_initialize(&wd_data->dev);
-+ wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
-+ wd_data->dev.class = &watchdog_class;
-+ wd_data->dev.parent = wdd->parent;
-+ wd_data->dev.groups = wdd->groups;
-+ wd_data->dev.release = watchdog_core_data_release;
-+ dev_set_drvdata(&wd_data->dev, wdd);
-+ dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
-+
- /* Fill in the data structures */
- cdev_init(&wd_data->cdev, &watchdog_fops);
-- wd_data->cdev.owner = wdd->ops->owner;
-
- /* Add the device */
-- err = cdev_add(&wd_data->cdev, devno, 1);
-+ err = cdev_device_add(&wd_data->cdev, &wd_data->dev);
- if (err) {
- pr_err("watchdog%d unable to add device %d:%d\n",
- wdd->id, MAJOR(watchdog_devt), wdd->id);
- if (wdd->id == 0) {
- misc_deregister(&watchdog_miscdev);
- old_wd_data = NULL;
-- kref_put(&wd_data->kref, watchdog_core_data_release);
-+ put_device(&wd_data->dev);
- }
- return err;
- }
-
-+ wd_data->cdev.owner = wdd->ops->owner;
-+
- /* Record time of most recent heartbeat as 'just before now'. */
- wd_data->last_hw_keepalive = jiffies - 1;
-
-@@ -960,7 +973,7 @@ static int watchdog_cdev_register(struct
- */
- if (watchdog_hw_running(wdd)) {
- __module_get(wdd->ops->owner);
-- kref_get(&wd_data->kref);
-+ get_device(&wd_data->dev);
- queue_delayed_work(watchdog_wq, &wd_data->work, 0);
- }
-
-@@ -979,7 +992,7 @@ static void watchdog_cdev_unregister(str
- {
- struct watchdog_core_data *wd_data = wdd->wd_data;
-
-- cdev_del(&wd_data->cdev);
-+ cdev_device_del(&wd_data->cdev, &wd_data->dev);
- if (wdd->id == 0) {
- misc_deregister(&watchdog_miscdev);
- old_wd_data = NULL;
-@@ -992,15 +1005,9 @@ static void watchdog_cdev_unregister(str
-
- cancel_delayed_work_sync(&wd_data->work);
-
-- kref_put(&wd_data->kref, watchdog_core_data_release);
-+ put_device(&wd_data->dev);
- }
-
--static struct class watchdog_class = {
-- .name = "watchdog",
-- .owner = THIS_MODULE,
-- .dev_groups = wdt_groups,
--};
--
- /*
- * watchdog_dev_register: register a watchdog device
- * @wdd: watchdog device
-@@ -1012,27 +1019,14 @@ static struct class watchdog_class = {
-
- int watchdog_dev_register(struct watchdog_device *wdd)
- {
-- struct device *dev;
-- dev_t devno;
- int ret;
-
-- devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
--
-- ret = watchdog_cdev_register(wdd, devno);
-+ ret = watchdog_cdev_register(wdd);
- if (ret)
- return ret;
-
-- dev = device_create_with_groups(&watchdog_class, wdd->parent,
-- devno, wdd, wdd->groups,
-- "watchdog%d", wdd->id);
-- if (IS_ERR(dev)) {
-- watchdog_cdev_unregister(wdd);
-- return PTR_ERR(dev);
-- }
--
- ret = watchdog_register_pretimeout(wdd);
- if (ret) {
-- device_destroy(&watchdog_class, devno);
- watchdog_cdev_unregister(wdd);
- }
-
-@@ -1050,7 +1044,6 @@ int watchdog_dev_register(struct watchdo
- void watchdog_dev_unregister(struct watchdog_device *wdd)
- {
- watchdog_unregister_pretimeout(wdd);
-- device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
- watchdog_cdev_unregister(wdd);
- }
-
projects / thirdparty / kernel / stable-queue.git / commitdiff
