From cebf8fd16900fdfd58c0028617944f808f97fe50 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sun, 10 Jul 2016 19:27:36 +0800 Subject: [PATCH] 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. Cc: Yijing Wang Reported-by: Chandra Sekhar Lingutla Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 0a8bdade53f2..88df65d1e6f6 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -836,11 +836,29 @@ static struct kobject *get_device_parent(struct device *dev, 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) +{ + return dev->kobj.parent; +} + +/* + * 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); @@ -848,11 +866,6 @@ 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) { struct device_node *of_node = dev_of_node(dev); @@ -1028,6 +1041,7 @@ int device_add(struct device *dev) struct kobject *kobj; struct class_interface *class_intf; int error = -EINVAL; + struct kobject *glue_dir = NULL; dev = get_device(dev); if (!dev) @@ -1072,8 +1086,10 @@ 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) @@ -1154,9 +1170,10 @@ done: device_remove_file(dev, &dev_attr_uevent); 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); put_device(parent); name_error: kfree(dev->p); @@ -1232,6 +1249,7 @@ EXPORT_SYMBOL_GPL(put_device); 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 @@ -1276,8 +1294,9 @@ void device_del(struct device *dev) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_REMOVED_DEVICE, 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); } EXPORT_SYMBOL_GPL(device_del); -- 2.20.1