OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

driver core: Establish order of operations for device_add and device_del via bitflag 

Add an additional bit flag to the device_private struct named "dead".

This additional flag provides a guarantee that when a device_del is
executed on a given interface an async worker will not attempt to attach
the driver following the earlier device_del call. Previously this
guarantee was not present and could result in the device_del call
attempting to remove a driver from an interface only to have the async
worker attempt to probe the driver later when it finally completes the
asynchronous probe call.

One additional change added was that I pulled the check for dev->driver
out of the __device_attach_driver call and instead placed it in the
__device_attach_async_helper call. This was motivated by the fact that the
only other caller of this, __device_attach, had already taken the
device_lock() and checked for dev->driver. Instead of testing for this
twice in this path it makes more sense to just consolidate the dev->dead
and dev->driver checks together into one set of checks.

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 10:39:10 -08:00 committed by Greg Kroah-Hartman
parent 0fe6f7874d
commit 3451a495ef
3 changed files with 26 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/base/base.h
View File

@ -67,6 +67,9 @@ struct driver_private {
* probed first.
* @device - pointer back to the struct device that this structure is
* associated with.
* @dead - This device is currently either in the process of or has been
* removed from the system. Any asynchronous events scheduled for this
* device should exit without taking any action.
*
* Nothing outside of the driver core should ever touch these fields.
*/
@ -78,6 +81,7 @@ struct device_private {
struct klist_node knode_class;
struct list_head deferred_probe;
struct device *device;
u8 dead:1;
};
#define to_device_private_parent(obj) \
container_of(obj, struct device_private, knode_parent)

11
drivers/base/core.c
View File

@ -2080,6 +2080,17 @@ void device_del(struct device *dev)
struct kobject *glue_dir = NULL;
struct class_interface *class_intf;
/*
* Hold the device lock and set the "dead" flag to guarantee that
* the update behavior is consistent with the other bitfields near
* it and that we cannot have an asynchronous probe routine trying
* to run while we are tearing out the bus/class/sysfs from
* underneath the device.
*/
device_lock(dev);
dev->p->dead = true;
device_unlock(dev);
/* Notify clients of device removal. This call must come
* before dpm_sysfs_remove().
*/

22
drivers/base/dd.c
View File

@ -731,15 +731,6 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
bool async_allowed;
int ret;
/*
* Check if device has already been claimed. This may
* happen with driver loading, device discovery/registration,
* and deferred probe processing happens all at once with
* multiple threads.
*/
if (dev->driver)
return -EBUSY;
ret = driver_match_device(drv, dev);
if (ret == 0) {
/* no match */
@ -774,6 +765,15 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
device_lock(dev);
/*
* Check if device has already been removed or claimed. This may
* happen with driver loading, device discovery/registration,
* and deferred probe processing happens all at once with
* multiple threads.
*/
if (dev->p->dead || dev->driver)
goto out_unlock;
if (dev->parent)
pm_runtime_get_sync(dev->parent);
@ -784,7 +784,7 @@ static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
if (dev->parent)
pm_runtime_put(dev->parent);
out_unlock:
device_unlock(dev);
put_device(dev);
@ -897,7 +897,7 @@ static int __driver_attach(struct device *dev, void *data)
if (dev->parent && dev->bus->need_parent_lock)
device_lock(dev->parent);
device_lock(dev);
if (!dev->driver)
if (!dev->p->dead && !dev->driver)
driver_probe_device(drv, dev);
device_unlock(dev);
if (dev->parent && dev->bus->need_parent_lock)