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authorAlexander Duyck <alexander.h.duyck@linux.intel.com>2019-01-22 10:39:16 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-31 14:20:53 +0100
commited88747c6c4a2fc2f961a36d4c50cb0868c30229 (patch)
tree482ff0b5ec8f143ea79914d2029fae63ce407e7b /drivers/base/dd.c
parent3451a495ef244a88ed6317a035299d835554d579 (diff)
downloadlinux-ed88747c6c4a2fc2f961a36d4c50cb0868c30229.tar.bz2
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>
Diffstat (limited to 'drivers/base/dd.c')
-rw-r--r--drivers/base/dd.c95
1 files changed, 75 insertions, 20 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 636cd16b1b62..34556359c7da 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -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);
}
/**
@@ -1028,6 +1071,18 @@ 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.
*/