[driver-core,v7,1/9] driver core: Move async_synchronize_full call
diff mbox series

Message ID 154345153162.18040.15354788106932190561.stgit@ahduyck-desk1.amr.corp.intel.com
State Superseded
Headers show
Series
  • Add NUMA aware async_schedule calls
Related show

Commit Message

Alexander Duyck Nov. 29, 2018, 12:32 a.m. UTC
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>
---
 drivers/base/dd.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Luis Chamberlain Nov. 30, 2018, 11:21 p.m. UTC | #1
On Wed, Nov 28, 2018 at 04:32:11PM -0800, Alexander Duyck wrote:
> 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>

  Luis

> ---
>  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 689ac9dc6d81..88713f182086 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -931,9 +931,6 @@ 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)
> @@ -1039,6 +1036,9 @@ 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)) {
>

Patch
diff mbox series

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 689ac9dc6d81..88713f182086 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -931,9 +931,6 @@  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)
@@ -1039,6 +1036,9 @@  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)) {