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driver core: fix race between creating/querying glue dir and its cleanup 

The global mutex of 'gdp_mutex' is used to serialize creating/querying
glue dir and its cleanup. Turns out it isn't a perfect way because
part(kobj_kset_leave()) of the actual cleanup action() is done inside
the release handler of the glue dir kobject. That means gdp_mutex has
to be held before releasing the last reference count of the glue dir
kobject.

This patch moves glue dir's cleanup after kobject_del() in device_del()
for avoiding the race.

Change-Id: I92b10e62be8129ead5859a285bf964ab0a3ae2fd
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Yijing Wang <wangyijing@huawei.com>
Reported-by: Chandra Sekhar Lingutla <clingutla@codeaurora.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Patch-mainline: linux-arm-kernel @ 2016/4/26 22:57:28
		https://lkml.org/lkml/2016/4/26/647
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
This commit is contained in:
Ming Lei 2016-04-26 10:05:44 +05:30 committed by Gerrit - the friendly Code Review server
parent b52f838665
commit 760aaa7e3f
1 changed files with 29 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
drivers/base/core.c
View File

@ -826,12 +826,30 @@ static struct kobject *get_device_parent(struct device *dev,
return &parent->kobj;
return NULL;
}
static inline bool live_in_glue_dir(struct kobject *kobj,
struct device *dev)
{
if (!kobj || !dev->class ||
kobj->kset != &dev->class->p->glue_dirs)
return false;
return true;
}
static inline struct kobject *get_glue_dir(struct device *dev)
{
if (live_in_glue_dir(&dev->kobj, dev))
return dev->kobj.parent;
return NULL;
}
/*
* make sure cleaning up dir as the last step, we need to make
* sure .release handler of kobject is run with holding the
* global lock
*/
static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
{
/* see if we live in a "glue" directory */
if (!glue_dir || !dev->class ||
glue_dir->kset != &dev->class->p->glue_dirs)
if (!live_in_glue_dir(glue_dir, dev))
return;
mutex_lock(&gdp_mutex);
@ -839,11 +857,6 @@ static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
mutex_unlock(&gdp_mutex);
}
static void cleanup_device_parent(struct device *dev)
{
cleanup_glue_dir(dev, dev->kobj.parent);
}
static int device_add_class_symlinks(struct device *dev)
{
int error;
@ -1006,6 +1019,7 @@ int device_add(struct device *dev)
struct device *parent = NULL;
struct kobject *kobj;
struct class_interface *class_intf;
struct kobject *glue_dir = NULL;
int error = -EINVAL;
dev = get_device(dev);
@ -1051,8 +1065,10 @@ int device_add(struct device *dev)
/* first, register with generic layer. */
/* we require the name to be set before, and pass NULL */
error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
if (error)
if (error) {
glue_dir = get_glue_dir(dev);
goto Error;
}
/* notify platform of device entry */
if (platform_notify)
@ -1141,9 +1157,10 @@ done:
device_remove_file(dev, &uevent_attr);
attrError:
kobject_uevent(&dev->kobj, KOBJ_REMOVE);
glue_dir = get_glue_dir(dev);
kobject_del(&dev->kobj);
Error:
cleanup_device_parent(dev);
cleanup_glue_dir(dev, glue_dir);
if (parent)
put_device(parent);
name_error:
@ -1216,6 +1233,7 @@ void put_device(struct device *dev)
void device_del(struct device *dev)
{
struct device *parent = dev->parent;
struct kobject *glue_dir = NULL;
struct class_interface *class_intf;
/* Notify clients of device removal. This call must come
@ -1257,8 +1275,9 @@ void device_del(struct device *dev)
if (platform_notify_remove)
platform_notify_remove(dev);
kobject_uevent(&dev->kobj, KOBJ_REMOVE);
cleanup_device_parent(dev);
glue_dir = get_glue_dir(dev);
kobject_del(&dev->kobj);
cleanup_glue_dir(dev, glue_dir);
put_device(parent);
}