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device core: Consolidate locking and unlocking of parent and device 

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>
This commit is contained in:
Alexander Duyck 2019-01-22 10:39:16 -08:00 committed by Greg Kroah-Hartman
parent 3451a495ef
commit ed88747c6c
3 changed files with 81 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/base/base.h
View File

@ -132,6 +132,8 @@ 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);

23
drivers/base/bus.c
View File

@ -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 */
@ -773,13 +763,8 @@ 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);

95
drivers/base/dd.c
View File

@ -867,6 +867,64 @@ 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;
@ -894,14 +952,7 @@ 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;
}
@ -932,15 +983,11 @@ 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
@ -993,16 +1040,12 @@ 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 +1070,18 @@ 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.