From: Alexander Duyck alexander.h.duyck@linux.intel.com

mainline inclusion from mainline-v5.1-rc1 commit ed88747 category: bugfix bugzilla: 176200 CVE: NA

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Try to 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.

This patch should produce no functional changes, it is meant to be a code clean-up/consolidation only.

Reviewed-by: Luis Chamberlain mcgrof@kernel.org Reviewed-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Dan Williams dan.j.williams@intel.com Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Alexander Duyck alexander.h.duyck@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com Reviewed-by: Hanjun Guo guohanjun@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/base/base.h | 2 + drivers/base/bus.c | 23 ++--------- drivers/base/dd.c | 95 +++++++++++++++++++++++++++++++++++---------- 3 files changed, 81 insertions(+), 39 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h index 559b047de9f75..2d270b8c731a0 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -128,6 +128,8 @@ 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 e06a57936cc96..38a09ca932a3b 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -187,11 +187,7 @@ 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); @@ -214,13 +210,7 @@ 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 */ @@ -774,13 +764,8 @@ 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 35112842b50e8..24d3a6289e9bf 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -865,6 +865,64 @@ 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_unlock - 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 device has been removed or someone has already successfully + * bound a driver before us just skip the driver probe call. + */ + if (!dev->p->dead && !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; @@ -892,14 +950,7 @@ 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->p->dead && !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; } @@ -930,15 +981,11 @@ static void __device_release_driver(struct device *dev, struct device *parent) drv = dev->driver; if (drv) { while (device_links_busy(dev)) { - device_unlock(dev); - if (parent && dev->bus->need_parent_lock) - device_unlock(parent); + __device_driver_unlock(dev, parent);

device_links_unbind_consumers(dev); - if (parent && dev->bus->need_parent_lock) - 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 @@ -991,16 +1038,12 @@ 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); }

/** @@ -1025,6 +1068,18 @@ 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.