From 35acfdd7253025e8441883fd8f879f5240844f95 Mon Sep 17 00:00:00 2001 From: Yoichi Yuasa Date: Sat, 15 Jul 2006 01:30:11 +0900 Subject: Driver core: fixed add_bind_files() definition When CONFIG_HOTPLUG is n, add_bind_files() definition is wrong. This patch has fixed it. Signed-off-by: Yoichi Yuasa Signed-off-by: Greg Kroah-Hartman --- drivers/base/bus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/base/bus.c') diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 2e954d07175..4d22a1d10a1 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -467,7 +467,7 @@ static void remove_bind_files(struct device_driver *drv) driver_remove_file(drv, &driver_attr_unbind); } #else -static inline void add_bind_files(struct device_driver *drv) {} +static inline int add_bind_files(struct device_driver *drv) { return 0; } static inline void remove_bind_files(struct device_driver *drv) {} #endif -- cgit v1.2.3-18-g5258 From f86db396ff455ed586751d21816a1ebd431264e5 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Mon, 14 Aug 2006 22:43:20 -0700 Subject: drivers/base: check errors Add lots of return-value checking. : fix bus_rescan_devices()] Cc: "Randy.Dunlap" Signed-off-by: Cornelia Huck Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/base/bus.c | 107 +++++++++++++++++++++++++++++++++++------------------ 1 file changed, 72 insertions(+), 35 deletions(-) (limited to 'drivers/base/bus.c') diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 4d22a1d10a1..aa685a20b64 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -371,12 +371,20 @@ int bus_add_device(struct device * dev) if (bus) { pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id); error = device_add_attrs(bus, dev); - if (!error) { - sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id); - sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "subsystem"); - sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus"); - } + if (error) + goto out; + error = sysfs_create_link(&bus->devices.kobj, + &dev->kobj, dev->bus_id); + if (error) + goto out; + error = sysfs_create_link(&dev->kobj, + &dev->bus->subsys.kset.kobj, "subsystem"); + if (error) + goto out; + error = sysfs_create_link(&dev->kobj, + &dev->bus->subsys.kset.kobj, "bus"); } +out: return error; } @@ -386,14 +394,19 @@ int bus_add_device(struct device * dev) * * - Try to attach to driver. */ -void bus_attach_device(struct device * dev) +int bus_attach_device(struct device * dev) { - struct bus_type * bus = dev->bus; + struct bus_type *bus = dev->bus; + int ret = 0; if (bus) { - device_attach(dev); - klist_add_tail(&dev->knode_bus, &bus->klist_devices); + ret = device_attach(dev); + if (ret >= 0) { + klist_add_tail(&dev->knode_bus, &bus->klist_devices); + ret = 0; + } } + return ret; } /** @@ -455,10 +468,17 @@ static void driver_remove_attrs(struct bus_type * bus, struct device_driver * dr * Thanks to drivers making their tables __devinit, we can't allow manual * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled. */ -static void add_bind_files(struct device_driver *drv) +static int __must_check add_bind_files(struct device_driver *drv) { - driver_create_file(drv, &driver_attr_unbind); - driver_create_file(drv, &driver_attr_bind); + int ret; + + ret = driver_create_file(drv, &driver_attr_unbind); + if (ret == 0) { + ret = driver_create_file(drv, &driver_attr_bind); + if (ret) + driver_remove_file(drv, &driver_attr_unbind); + } + return ret; } static void remove_bind_files(struct device_driver *drv) @@ -476,7 +496,7 @@ static inline void remove_bind_files(struct device_driver *drv) {} * @drv: driver. * */ -int bus_add_driver(struct device_driver * drv) +int bus_add_driver(struct device_driver *drv) { struct bus_type * bus = get_bus(drv->bus); int error = 0; @@ -484,27 +504,39 @@ int bus_add_driver(struct device_driver * drv) if (bus) { pr_debug("bus %s: add driver %s\n", bus->name, drv->name); error = kobject_set_name(&drv->kobj, "%s", drv->name); - if (error) { - put_bus(bus); - return error; - } + if (error) + goto out_put_bus; drv->kobj.kset = &bus->drivers; - if ((error = kobject_register(&drv->kobj))) { - put_bus(bus); - return error; - } + if ((error = kobject_register(&drv->kobj))) + goto out_put_bus; - driver_attach(drv); + error = driver_attach(drv); + if (error) + goto out_unregister; klist_add_tail(&drv->knode_bus, &bus->klist_drivers); module_add_driver(drv->owner, drv); - driver_add_attrs(bus, drv); - add_bind_files(drv); + error = driver_add_attrs(bus, drv); + if (error) { + /* How the hell do we get out of this pickle? Give up */ + printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n", + __FUNCTION__, drv->name); + } + error = add_bind_files(drv); + if (error) { + /* Ditto */ + printk(KERN_ERR "%s: add_bind_files(%s) failed\n", + __FUNCTION__, drv->name); + } } return error; +out_unregister: + kobject_unregister(&drv->kobj); +out_put_bus: + put_bus(bus); + return error; } - /** * bus_remove_driver - delete driver from bus's knowledge. * @drv: driver. @@ -530,16 +562,21 @@ void bus_remove_driver(struct device_driver * drv) /* Helper for bus_rescan_devices's iter */ -static int bus_rescan_devices_helper(struct device *dev, void *data) +static int __must_check bus_rescan_devices_helper(struct device *dev, + void *data) { + int ret = 0; + if (!dev->driver) { if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); - device_attach(dev); + ret = device_attach(dev); if (dev->parent) up(&dev->parent->sem); + if (ret > 0) + ret = 0; } - return 0; + return ret < 0 ? ret : 0; } /** @@ -550,9 +587,9 @@ static int bus_rescan_devices_helper(struct device *dev, void *data) * attached and rescan it against existing drivers to see if it matches * any by calling device_attach() for the unbound devices. */ -void bus_rescan_devices(struct bus_type * bus) +int bus_rescan_devices(struct bus_type * bus) { - bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper); + return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper); } /** @@ -564,7 +601,7 @@ void bus_rescan_devices(struct bus_type * bus) * to use if probing criteria changed during a devices lifetime and * driver attachment should change accordingly. */ -void device_reprobe(struct device *dev) +int device_reprobe(struct device *dev) { if (dev->driver) { if (dev->parent) /* Needed for USB */ @@ -573,14 +610,14 @@ void device_reprobe(struct device *dev) if (dev->parent) up(&dev->parent->sem); } - - bus_rescan_devices_helper(dev, NULL); + return bus_rescan_devices_helper(dev, NULL); } EXPORT_SYMBOL_GPL(device_reprobe); -struct bus_type * get_bus(struct bus_type * bus) +struct bus_type *get_bus(struct bus_type *bus) { - return bus ? container_of(subsys_get(&bus->subsys), struct bus_type, subsys) : NULL; + return bus ? container_of(subsys_get(&bus->subsys), + struct bus_type, subsys) : NULL; } void put_bus(struct bus_type * bus) -- cgit v1.2.3-18-g5258 From f2eaae197f4590c4d96f31b09b0ee9067421a95c Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 18 Sep 2006 16:22:34 -0400 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- drivers/base/bus.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/base/bus.c') diff --git a/drivers/base/bus.c b/drivers/base/bus.c index aa685a20b64..636af538a2b 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -392,6 +392,7 @@ out: * bus_attach_device - add device to bus * @dev: device tried to attach to a driver * + * - Add device to bus's list of devices. * - Try to attach to driver. */ int bus_attach_device(struct device * dev) @@ -400,11 +401,13 @@ int bus_attach_device(struct device * dev) int ret = 0; if (bus) { + dev->is_registered = 1; ret = device_attach(dev); if (ret >= 0) { klist_add_tail(&dev->knode_bus, &bus->klist_devices); ret = 0; - } + } else + dev->is_registered = 0; } return ret; } @@ -425,7 +428,8 @@ void bus_remove_device(struct device * dev) sysfs_remove_link(&dev->kobj, "bus"); sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id); device_remove_attrs(dev->bus, dev); - klist_remove(&dev->knode_bus); + dev->is_registered = 0; + klist_del(&dev->knode_bus); pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id); device_release_driver(dev); put_bus(dev->bus); -- cgit v1.2.3-18-g5258 From 81107bf531d2524afbcd61f3b4ad57a71295d591 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Mon, 18 Sep 2006 16:24:28 -0400 Subject: Driver core: Remove unneeded routines from driver core This patch (as783) simplifies the driver core slightly by removing four unnecessary _get and _put methods. It is vital that when a driver is removed from its bus's klist of registered drivers, or when a device is removed from a driver's klist of bound devices, that the klist updates complete synchronously. Otherwise the kernel might try binding an unregistered driver to a newly-registered device, or adding a device to the klist for a new driver before it has been removed from the old driver's klist. Since the removals must be synchronous, they don't need to update any reference counts. Hence the _get and _put methods can be dispensed with. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/base/bus.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) (limited to 'drivers/base/bus.c') diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 636af538a2b..12173d16bea 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -696,22 +696,6 @@ static void klist_devices_put(struct klist_node *n) put_device(dev); } -static void klist_drivers_get(struct klist_node *n) -{ - struct device_driver *drv = container_of(n, struct device_driver, - knode_bus); - - get_driver(drv); -} - -static void klist_drivers_put(struct klist_node *n) -{ - struct device_driver *drv = container_of(n, struct device_driver, - knode_bus); - - put_driver(drv); -} - /** * bus_register - register a bus with the system. * @bus: bus. @@ -747,7 +731,7 @@ int bus_register(struct bus_type * bus) goto bus_drivers_fail; klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put); - klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put); + klist_init(&bus->klist_drivers, NULL, NULL); bus_add_attrs(bus); pr_debug("bus type '%s' registered\n", bus->name); -- cgit v1.2.3-18-g5258