[driver-core PATCH v5 3/9] device core: Consolidate locking and unlocking of parent and device

This patch is meant to try and consolidate all of the locking and unlocking of both the parent and device when attaching or removing a driver from a given device. To do that I first consolidated the lock pattern into two functions __device_driver_lock and __device_driver_unlock. After doing that I then created functions specific to attaching and detaching the driver while acquiring these locks. By doing this I was able to reduce the number of spots where we touch need_parent_lock from 12 down to 4. Reviewed-by: Bart Van Assche <bvanassche(a)acm.org&gt; Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com&gt; Signed-off-by: Alexander Duyck <alexander.h.duyck(a)linux.intel.com&gt; --- drivers/base/base.h | 2 + drivers/base/bus.c | 23 ++----------- drivers/base/dd.c | 91 ++++++++++++++++++++++++++++++++++++++++----------- 3 files changed, 77 insertions(+), 39 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 7a419a7a6235..3f22ebd6117a 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -124,6 +124,8 @@ extern int driver_add_groups(struct device_driver *drv, const struct attribute_group **groups); extern void driver_remove_groups(struct device_driver *drv, const struct attribute_group **groups); +int device_driver_attach(struct device_driver *drv, struct device *dev); +void device_driver_detach(struct device *dev); extern char *make_class_name(const char *name, struct kobject *kobj); diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 8bfd27ec73d6..8a630f9bd880 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -184,11 +184,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf, dev = bus_find_device_by_name(bus, NULL, buf); if (dev && dev->driver == drv) { - if (dev->parent && dev->bus->need_parent_lock) - device_lock(dev->parent); - device_release_driver(dev); - if (dev->parent && dev->bus->need_parent_lock) - device_unlock(dev->parent); + device_driver_detach(dev); err = count; } put_device(dev); @@ -211,13 +207,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf, dev = bus_find_device_by_name(bus, NULL, buf); if (dev && dev->driver == NULL && driver_match_device(drv, dev)) { - if (dev->parent && bus->need_parent_lock) - device_lock(dev->parent); - device_lock(dev); - err = driver_probe_device(drv, dev); - device_unlock(dev); - if (dev->parent && bus->need_parent_lock) - device_unlock(dev->parent); + err = device_driver_attach(drv, dev); if (err > 0) { /* success */ @@ -769,13 +759,8 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices); */ int device_reprobe(struct device *dev) { - if (dev->driver) { - if (dev->parent && dev->bus->need_parent_lock) - device_lock(dev->parent); - device_release_driver(dev); - if (dev->parent && dev->bus->need_parent_lock) - device_unlock(dev->parent); - } + if (dev->driver) + device_driver_detach(dev); return bus_rescan_devices_helper(dev, NULL); } EXPORT_SYMBOL_GPL(device_reprobe); diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 169412ee4ae8..76c40fe69463 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -864,6 +864,60 @@ void device_initial_probe(struct device *dev) __device_attach(dev, true); } +/* + * __device_driver_lock - acquire locks needed to manipulate dev->drv + * @dev: Device we will update driver info for + * @parent: Parent device. Needed if the bus requires parent lock + * + * This function will take the required locks for manipulating dev->drv. + * Normally this will just be the @dev lock, but when called for a USB + * interface, @parent lock will be held as well. + */ +static void __device_driver_lock(struct device *dev, struct device *parent) +{ + if (parent && dev->bus->need_parent_lock) + device_lock(parent); + device_lock(dev); +} + +/* + * __device_driver_lock - release locks needed to manipulate dev->drv + * @dev: Device we will update driver info for + * @parent: Parent device. Needed if the bus requires parent lock + * + * This function will release the required locks for manipulating dev->drv. + * Normally this will just be the the @dev lock, but when called for a + * USB interface, @parent lock will be released as well. + */ +static void __device_driver_unlock(struct device *dev, struct device *parent) +{ + device_unlock(dev); + if (parent && dev->bus->need_parent_lock) + device_unlock(parent); +} + +/** + * device_driver_attach - attach a specific driver to a specific device + * @drv: Driver to attach + * @dev: Device to attach it to + * + * Manually attach driver to a device. Will acquire both @dev lock and + * @dev->parent lock if needed. + */ +int device_driver_attach(struct device_driver *drv, struct device *dev) +{ + int ret = 0; + + __device_driver_lock(dev, dev->parent); + + if (!dev->driver) + ret = driver_probe_device(drv, dev); + + __device_driver_unlock(dev, dev->parent); + + return ret; +} + static int __driver_attach(struct device *dev, void *data) { struct device_driver *drv = data; @@ -891,14 +945,7 @@ static int __driver_attach(struct device *dev, void *data) return ret; } /* ret > 0 means positive match */ - if (dev->parent && dev->bus->need_parent_lock) - device_lock(dev->parent); - device_lock(dev); - if (!dev->driver) - driver_probe_device(drv, dev); - device_unlock(dev); - if (dev->parent && dev->bus->need_parent_lock) - device_unlock(dev->parent); + device_driver_attach(drv, dev); return 0; } @@ -932,15 +979,11 @@ static void __device_release_driver(struct device *dev, struct device *parent) async_synchronize_full(); while (device_links_busy(dev)) { - device_unlock(dev); - if (parent) - device_unlock(parent); + __device_driver_unlock(dev, parent); device_links_unbind_consumers(dev); - if (parent) - device_lock(parent); - device_lock(dev); + __device_driver_lock(dev, parent); /* * A concurrent invocation of the same function might * have released the driver successfully while this one @@ -993,16 +1036,12 @@ void device_release_driver_internal(struct device *dev, struct device_driver *drv, struct device *parent) { - if (parent && dev->bus->need_parent_lock) - device_lock(parent); + __device_driver_lock(dev, parent); - device_lock(dev); if (!drv || drv == dev->driver) __device_release_driver(dev, parent); - device_unlock(dev); - if (parent && dev->bus->need_parent_lock) - device_unlock(parent); + __device_driver_unlock(dev, parent); } /** @@ -1027,6 +1066,18 @@ void device_release_driver(struct device *dev) } EXPORT_SYMBOL_GPL(device_release_driver); +/** + * device_driver_detach - detach driver from a specific device + * @dev: device to detach driver from + * + * Detach driver from device. Will acquire both @dev lock and @dev->parent + * lock if needed. + */ +void device_driver_detach(struct device *dev) +{ + device_release_driver_internal(dev, NULL, dev->parent); +} + /** * driver_detach - detach driver from all devices it controls. * @drv: driver.