diff mbox series

[driver-core,v6,3/9] device core: Consolidate locking and unlocking of parent and device

Message ID 154170041590.12967.4367086895437513524.stgit@ahduyck-desk1.jf.intel.com (mailing list archive)
State Superseded
Headers show
Series Add NUMA aware async_schedule calls | expand

Commit Message

Alexander Duyck Nov. 8, 2018, 6:06 p.m. UTC 
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.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
---
 drivers/base/base.h |    2 +
 drivers/base/bus.c  |   23 ++-----------
 drivers/base/dd.c   |   91 ++++++++++++++++++++++++++++++++++++++++-----------
 3 files changed, 77 insertions(+), 39 deletions(-)

Comments

Jane Chu Nov. 8, 2018, 10:43 p.m. UTC | #1 
Hi, Alex,


On 11/08/2018 10:06 AM, Alexander Duyck wrote:
> +/*
> + * __device_driver_lock - release locks needed to manipulate dev->drv

You meant to say __device_driver_unlock, right?

> + * @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);
> +}

-jane
Alexander Duyck Nov. 8, 2018, 10:48 p.m. UTC | #2 
On Thu, 2018-11-08 at 14:43 -0800, jane.chu@oracle.com wrote:
> Hi, Alex,
> 
> 
> On 11/08/2018 10:06 AM, Alexander Duyck wrote:
> > +/*
> > + * __device_driver_lock - release locks needed to manipulate dev->drv
> 
> You meant to say __device_driver_unlock, right?

Yes, you are correct.

> > + * @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);
> > +}
> 
> -jane

Thanks.

- Alex
Dan Williams Nov. 27, 2018, 1:44 a.m. UTC | #3 
On Thu, Nov 8, 2018 at 10:06 AM Alexander Duyck
<alexander.h.duyck@linux.intel.com> wrote:
>
> 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.
>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>

I was going to complain about the new addition of "This function" in
the kernel-doc, but there are other occurrences in the file so that
can wait for some future cleanup.

I missed the __device_driver_unlock comment that Jane caught.

With that fixed up.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
diff mbox series

Patch

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 7a419a7a6235..3f22ebd6117a 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -124,6 +124,8 @@  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 8bfd27ec73d6..8a630f9bd880 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -184,11 +184,7 @@  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);
@@ -211,13 +207,7 @@  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 */
@@ -769,13 +759,8 @@  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 169412ee4ae8..76c40fe69463 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -864,6 +864,60 @@  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_lock - 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 (!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;
@@ -891,14 +945,7 @@  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->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 +979,11 @@  static void __device_release_driver(struct device *dev, struct device *parent)
 			async_synchronize_full();
 
 		while (device_links_busy(dev)) {
-			device_unlock(dev);
-			if (parent)
-				device_unlock(parent);
+			__device_driver_unlock(dev, parent);
 
 			device_links_unbind_consumers(dev);
-			if (parent)
-				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 +1036,12 @@  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 +1066,18 @@  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.