4.20-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit c37d721c68ad88925ba0e72f6e14acb829a8c6bb ]
Move the async_synchronize_full call out of __device_release_driver and into driver_detach.
The idea behind this is that the async_synchronize_full call will only guarantee that any existing async operations are flushed. This doesn't do anything to guarantee that a hotplug event that may occur while we are doing the release of the driver will not be asynchronously scheduled.
By moving this into the driver_detach path we can avoid potential deadlocks as we aren't holding the device lock at this point and we should not have the driver we want to flush loaded so the flush will take care of any asynchronous events the driver we are detaching might have scheduled.
Fixes: 765230b5f084 ("driver-core: add asynchronous probing support for drivers") Reviewed-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Alexander Duyck alexander.h.duyck@linux.intel.com Reviewed-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/dd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c index dbba123e058d..9d6604b50d75 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -928,9 +928,6 @@ static void __device_release_driver(struct device *dev, struct device *parent)
drv = dev->driver; if (drv) { - if (driver_allows_async_probing(drv)) - async_synchronize_full(); - while (device_links_busy(dev)) { device_unlock(dev); if (parent && dev->bus->need_parent_lock) @@ -1036,6 +1033,9 @@ void driver_detach(struct device_driver *drv) struct device_private *dev_prv; struct device *dev;
+ if (driver_allows_async_probing(drv)) + async_synchronize_full(); + for (;;) { spin_lock(&drv->p->klist_devices.k_lock); if (list_empty(&drv->p->klist_devices.k_list)) {