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linux-next/include/linux/device.h
Alan Stern f2eaae197f Driver core: Fix potential deadlock in driver core 
There is a potential deadlock in the driver core.  It boils down to
the fact that bus_remove_device() calls klist_remove() instead of
klist_del(), thereby waiting until the reference count of the
klist_node in the bus's klist of devices drops to 0.  The refcount
can't reach 0 so long as a modprobe process is trying to bind a new
driver to the device being removed, by calling __driver_attach().  The
problem is that __driver_attach() tries to acquire the device's
parent's semaphore, but the caller of bus_remove_device() is quite
likely to own that semaphore already.

It isn't sufficient just to replace klist_remove() with klist_del().
Doing so runs the risk that the device would remain on the bus's klist
of devices for some time, and so could be bound to another driver even
after it was unregistered.  What's needed is a new way to distinguish
whether or not a device is registered, based on a criterion other than
whether its klist_node is linked into the bus's klist of devices.  That
way driver binding can fail when the device is unregistered, even if
it is still linked into the klist.

This patch (as782) implements the solution, by adding a new bitflag to
indiate when a struct device is registered, by testing the flag before
allowing a driver to bind a device, and by changing the definition of
the device_is_registered() inline.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-09-25 21:08:40 -07:00

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/*
* device.h - generic, centralized driver model
*
* Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
*
* This file is released under the GPLv2
*
* See Documentation/driver-model/ for more information.
*/
#ifndef _DEVICE_H_
#define _DEVICE_H_
#include <linux/ioport.h>
#include <linux/kobject.h>
#include <linux/klist.h>
#include <linux/list.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <asm/semaphore.h>
#include <asm/atomic.h>
#define DEVICE_NAME_SIZE 50
#define DEVICE_NAME_HALF __stringify(20) /* Less than half to accommodate slop */
#define DEVICE_ID_SIZE 32
#define BUS_ID_SIZE KOBJ_NAME_LEN
struct device;
struct device_driver;
struct class;
struct class_device;
struct bus_type {
const char * name;
struct subsystem subsys;
struct kset drivers;
struct kset devices;
struct klist klist_devices;
struct klist klist_drivers;
struct bus_attribute * bus_attrs;
struct device_attribute * dev_attrs;
struct driver_attribute * drv_attrs;
int (*match)(struct device * dev, struct device_driver * drv);
int (*uevent)(struct device *dev, char **envp,
int num_envp, char *buffer, int buffer_size);
int (*probe)(struct device * dev);
int (*remove)(struct device * dev);
void (*shutdown)(struct device * dev);
int (*suspend)(struct device * dev, pm_message_t state);
int (*suspend_late)(struct device * dev, pm_message_t state);
int (*resume_early)(struct device * dev);
int (*resume)(struct device * dev);
};
extern int __must_check bus_register(struct bus_type * bus);
extern void bus_unregister(struct bus_type * bus);
extern int __must_check bus_rescan_devices(struct bus_type * bus);
/* iterator helpers for buses */
int bus_for_each_dev(struct bus_type * bus, struct device * start, void * data,
int (*fn)(struct device *, void *));
struct device * bus_find_device(struct bus_type *bus, struct device *start,
void *data, int (*match)(struct device *, void *));
int __must_check bus_for_each_drv(struct bus_type *bus,
struct device_driver *start, void *data,
int (*fn)(struct device_driver *, void *));
/* driverfs interface for exporting bus attributes */
struct bus_attribute {
struct attribute attr;
ssize_t (*show)(struct bus_type *, char * buf);
ssize_t (*store)(struct bus_type *, const char * buf, size_t count);
};
#define BUS_ATTR(_name,_mode,_show,_store) \
struct bus_attribute bus_attr_##_name = __ATTR(_name,_mode,_show,_store)
extern int __must_check bus_create_file(struct bus_type *,
struct bus_attribute *);
extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
struct device_driver {
const char * name;
struct bus_type * bus;
struct completion unloaded;
struct kobject kobj;
struct klist klist_devices;
struct klist_node knode_bus;
struct module * owner;
int (*probe) (struct device * dev);
int (*remove) (struct device * dev);
void (*shutdown) (struct device * dev);
int (*suspend) (struct device * dev, pm_message_t state);
int (*resume) (struct device * dev);
unsigned int multithread_probe:1;
};
extern int __must_check driver_register(struct device_driver * drv);
extern void driver_unregister(struct device_driver * drv);
extern struct device_driver * get_driver(struct device_driver * drv);
extern void put_driver(struct device_driver * drv);
extern struct device_driver *driver_find(const char *name, struct bus_type *bus);
extern int driver_probe_done(void);
/* driverfs interface for exporting driver attributes */
struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *, char * buf);
ssize_t (*store)(struct device_driver *, const char * buf, size_t count);
};
#define DRIVER_ATTR(_name,_mode,_show,_store) \
struct driver_attribute driver_attr_##_name = __ATTR(_name,_mode,_show,_store)
extern int __must_check driver_create_file(struct device_driver *,
struct driver_attribute *);
extern void driver_remove_file(struct device_driver *, struct driver_attribute *);
extern int __must_check driver_for_each_device(struct device_driver * drv,
struct device *start, void *data,
int (*fn)(struct device *, void *));
struct device * driver_find_device(struct device_driver *drv,
struct device *start, void *data,
int (*match)(struct device *, void *));
/*
* device classes
*/
struct class {
const char * name;
struct module * owner;
struct subsystem subsys;
struct list_head children;
struct list_head devices;
struct list_head interfaces;
struct semaphore sem; /* locks both the children and interfaces lists */
struct kobject *virtual_dir;
struct class_attribute * class_attrs;
struct class_device_attribute * class_dev_attrs;
struct device_attribute * dev_attrs;
int (*uevent)(struct class_device *dev, char **envp,
int num_envp, char *buffer, int buffer_size);
int (*dev_uevent)(struct device *dev, char **envp, int num_envp,
char *buffer, int buffer_size);
void (*release)(struct class_device *dev);
void (*class_release)(struct class *class);
void (*dev_release)(struct device *dev);
int (*suspend)(struct device *, pm_message_t state);
int (*resume)(struct device *);
};
extern int __must_check class_register(struct class *);
extern void class_unregister(struct class *);
struct class_attribute {
struct attribute attr;
ssize_t (*show)(struct class *, char * buf);
ssize_t (*store)(struct class *, const char * buf, size_t count);
};
#define CLASS_ATTR(_name,_mode,_show,_store) \
struct class_attribute class_attr_##_name = __ATTR(_name,_mode,_show,_store)
extern int __must_check class_create_file(struct class *,
const struct class_attribute *);
extern void class_remove_file(struct class *, const struct class_attribute *);
struct class_device_attribute {
struct attribute attr;
ssize_t (*show)(struct class_device *, char * buf);
ssize_t (*store)(struct class_device *, const char * buf, size_t count);
};
#define CLASS_DEVICE_ATTR(_name,_mode,_show,_store) \
struct class_device_attribute class_device_attr_##_name = \
__ATTR(_name,_mode,_show,_store)
extern int __must_check class_device_create_file(struct class_device *,
const struct class_device_attribute *);
/**
* struct class_device - class devices
* @class: pointer to the parent class for this class device. This is required.
* @devt: for internal use by the driver core only.
* @node: for internal use by the driver core only.
* @kobj: for internal use by the driver core only.
* @devt_attr: for internal use by the driver core only.
* @groups: optional additional groups to be created
* @dev: if set, a symlink to the struct device is created in the sysfs
* directory for this struct class device.
* @class_data: pointer to whatever you want to store here for this struct
* class_device. Use class_get_devdata() and class_set_devdata() to get and
* set this pointer.
* @parent: pointer to a struct class_device that is the parent of this struct
* class_device. If NULL, this class_device will show up at the root of the
* struct class in sysfs (which is probably what you want to have happen.)
* @release: pointer to a release function for this struct class_device. If
* set, this will be called instead of the class specific release function.
* Only use this if you want to override the default release function, like
* when you are nesting class_device structures.
* @uevent: pointer to a uevent function for this struct class_device. If
* set, this will be called instead of the class specific uevent function.
* Only use this if you want to override the default uevent function, like
* when you are nesting class_device structures.
*/
struct class_device {
struct list_head node;
struct kobject kobj;
struct class * class; /* required */
dev_t devt; /* dev_t, creates the sysfs "dev" */
struct class_device_attribute *devt_attr;
struct class_device_attribute uevent_attr;
struct device * dev; /* not necessary, but nice to have */
void * class_data; /* class-specific data */
struct class_device *parent; /* parent of this child device, if there is one */
struct attribute_group ** groups; /* optional groups */
void (*release)(struct class_device *dev);
int (*uevent)(struct class_device *dev, char **envp,
int num_envp, char *buffer, int buffer_size);
char class_id[BUS_ID_SIZE]; /* unique to this class */
};
static inline void *
class_get_devdata (struct class_device *dev)
{
return dev->class_data;
}
static inline void
class_set_devdata (struct class_device *dev, void *data)
{
dev->class_data = data;
}
extern int __must_check class_device_register(struct class_device *);
extern void class_device_unregister(struct class_device *);
extern void class_device_initialize(struct class_device *);
extern int __must_check class_device_add(struct class_device *);
extern void class_device_del(struct class_device *);
extern int class_device_rename(struct class_device *, char *);
extern struct class_device * class_device_get(struct class_device *);
extern void class_device_put(struct class_device *);
extern void class_device_remove_file(struct class_device *,
const struct class_device_attribute *);
extern int __must_check class_device_create_bin_file(struct class_device *,
struct bin_attribute *);
extern void class_device_remove_bin_file(struct class_device *,
struct bin_attribute *);
struct class_interface {
struct list_head node;
struct class *class;
int (*add) (struct class_device *, struct class_interface *);
void (*remove) (struct class_device *, struct class_interface *);
int (*add_dev) (struct device *, struct class_interface *);
void (*remove_dev) (struct device *, struct class_interface *);
};
extern int __must_check class_interface_register(struct class_interface *);
extern void class_interface_unregister(struct class_interface *);
extern struct class *class_create(struct module *owner, const char *name);
extern void class_destroy(struct class *cls);
extern struct class_device *class_device_create(struct class *cls,
struct class_device *parent,
dev_t devt,
struct device *device,
const char *fmt, ...)
__attribute__((format(printf,5,6)));
extern void class_device_destroy(struct class *cls, dev_t devt);
/* interface for exporting device attributes */
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t (*store)(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
};
#define DEVICE_ATTR(_name,_mode,_show,_store) \
struct device_attribute dev_attr_##_name = __ATTR(_name,_mode,_show,_store)
extern int __must_check device_create_file(struct device *device,
struct device_attribute * entry);
extern void device_remove_file(struct device * dev, struct device_attribute * attr);
extern int __must_check device_create_bin_file(struct device *dev,
struct bin_attribute *attr);
extern void device_remove_bin_file(struct device *dev,
struct bin_attribute *attr);
struct device {
struct klist klist_children;
struct klist_node knode_parent; /* node in sibling list */
struct klist_node knode_driver;
struct klist_node knode_bus;
struct device * parent;
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
unsigned is_registered:1;
struct device_attribute uevent_attr;
struct device_attribute *devt_attr;
struct semaphore sem; /* semaphore to synchronize calls to
* its driver.
*/
struct bus_type * bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this
device */
void *driver_data; /* data private to the driver */
void *platform_data; /* Platform specific data, device
core doesn't touch it */
void *firmware_data; /* Firmware specific data (e.g. ACPI,
BIOS data),reserved for device core*/
struct dev_pm_info power;
u64 *dma_mask; /* dma mask (if dma'able device) */
u64 coherent_dma_mask;/* Like dma_mask, but for
alloc_coherent mappings as
not all hardware supports
64 bit addresses for consistent
allocations such descriptors. */
struct list_head dma_pools; /* dma pools (if dma'ble) */
struct dma_coherent_mem *dma_mem; /* internal for coherent mem
override */
/* class_device migration path */
struct list_head node;
struct class *class; /* optional*/
dev_t devt; /* dev_t, creates the sysfs "dev" */
struct attribute_group **groups; /* optional groups */
void (*release)(struct device * dev);
};
static inline void *
dev_get_drvdata (struct device *dev)
{
return dev->driver_data;
}
static inline void
dev_set_drvdata (struct device *dev, void *data)
{
dev->driver_data = data;
}
static inline int device_is_registered(struct device *dev)
{
return dev->is_registered;
}
/*
* High level routines for use by the bus drivers
*/
extern int __must_check device_register(struct device * dev);
extern void device_unregister(struct device * dev);
extern void device_initialize(struct device * dev);
extern int __must_check device_add(struct device * dev);
extern void device_del(struct device * dev);
extern int __must_check device_for_each_child(struct device *, void *,
int (*fn)(struct device *, void *));
extern int device_rename(struct device *dev, char *new_name);
/*
* Manual binding of a device to driver. See drivers/base/bus.c
* for information on use.
*/
extern int __must_check device_bind_driver(struct device *dev);
extern void device_release_driver(struct device * dev);
extern int __must_check device_attach(struct device * dev);
extern int __must_check driver_attach(struct device_driver *drv);
extern int __must_check device_reprobe(struct device *dev);
/*
* Easy functions for dynamically creating devices on the fly
*/
extern struct device *device_create(struct class *cls, struct device *parent,
dev_t devt, const char *fmt, ...)
__attribute__((format(printf,4,5)));
extern void device_destroy(struct class *cls, dev_t devt);
extern int virtual_device_parent(struct device *dev);
/*
* Platform "fixup" functions - allow the platform to have their say
* about devices and actions that the general device layer doesn't
* know about.
*/
/* Notify platform of device discovery */
extern int (*platform_notify)(struct device * dev);
extern int (*platform_notify_remove)(struct device * dev);
/**
* get_device - atomically increment the reference count for the device.
*
*/
extern struct device * get_device(struct device * dev);
extern void put_device(struct device * dev);
/* drivers/base/power/shutdown.c */
extern void device_shutdown(void);
/* drivers/base/firmware.c */
extern int __must_check firmware_register(struct subsystem *);
extern void firmware_unregister(struct subsystem *);
/* debugging and troubleshooting/diagnostic helpers. */
extern const char *dev_driver_string(struct device *dev);
#define dev_printk(level, dev, format, arg...) \
printk(level "%s %s: " format , dev_driver_string(dev) , (dev)->bus_id , ## arg)
#ifdef DEBUG
#define dev_dbg(dev, format, arg...) \
dev_printk(KERN_DEBUG , dev , format , ## arg)
#else
#define dev_dbg(dev, format, arg...) do { (void)(dev); } while (0)
#endif
#define dev_err(dev, format, arg...) \
dev_printk(KERN_ERR , dev , format , ## arg)
#define dev_info(dev, format, arg...) \
dev_printk(KERN_INFO , dev , format , ## arg)
#define dev_warn(dev, format, arg...) \
dev_printk(KERN_WARNING , dev , format , ## arg)
#define dev_notice(dev, format, arg...) \
dev_printk(KERN_NOTICE , dev , format , ## arg)
/* Create alias, so I can be autoloaded. */
#define MODULE_ALIAS_CHARDEV(major,minor) \
MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
#define MODULE_ALIAS_CHARDEV_MAJOR(major) \
MODULE_ALIAS("char-major-" __stringify(major) "-*")
#endif /* _DEVICE_H_ */
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