[PATCH] libata: transport: Remove circular dependency at free time

[Gwendal Grignou <gwendal@chromium.org>]

From: Tejun Heo <tj@kernel.org>

Without this patch, failed probe would not free resources like irq.

ata port tdev object currently hold a reference to the ata port object.
Therefore the ata port object release function will not get called until
the ata_tport_release is called. But that would never happen, releasing
the last reference of ata port dev is done by scsi_host_release, which
is called by ata_host_release when the ata port object is released.

The ata tranport device objects actually do not need to explicitly hold
a reference to their real counterpart, given the transport objects are
the children of these objects and device_add() is call for each child.
We know the parent will not be deleted until we call the child
device_del().

Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Tested-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 drivers/ata/libata-transport.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
index 46698232e6bf..19e6e539a061 100644
--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -224,7 +224,6 @@ static DECLARE_TRANSPORT_CLASS(ata_port_class,
 
 static void ata_tport_release(struct device *dev)
 {
-	put_device(dev->parent);
 }
 
 /**
@@ -284,7 +283,7 @@ int ata_tport_add(struct device *parent,
 	device_initialize(dev);
 	dev->type = &ata_port_type;
 
-	dev->parent = get_device(parent);
+	dev->parent = parent;
 	dev->release = ata_tport_release;
 	dev_set_name(dev, "ata%d", ap->print_id);
 	transport_setup_device(dev);
@@ -348,7 +347,6 @@ static DECLARE_TRANSPORT_CLASS(ata_link_class,
 
 static void ata_tlink_release(struct device *dev)
 {
-	put_device(dev->parent);
 }
 
 /**
@@ -410,7 +408,7 @@ int ata_tlink_add(struct ata_link *link)
 	int error;
 
 	device_initialize(dev);
-	dev->parent = get_device(&ap->tdev);
+	dev->parent = &ap->tdev;
 	dev->release = ata_tlink_release;
 	if (ata_is_host_link(link))
 		dev_set_name(dev, "link%d", ap->print_id);
@@ -589,7 +587,6 @@ static DECLARE_TRANSPORT_CLASS(ata_dev_class,
 
 static void ata_tdev_release(struct device *dev)
 {
-	put_device(dev->parent);
 }
 
 /**
@@ -662,7 +659,7 @@ static int ata_tdev_add(struct ata_device *ata_dev)
 	int error;
 
 	device_initialize(dev);
-	dev->parent = get_device(&link->tdev);
+	dev->parent = &link->tdev;
 	dev->release = ata_tdev_release;
 	if (ata_is_host_link(link))
 		dev_set_name(dev, "dev%d.%d", ap->print_id,ata_dev->devno);
-- 
2.12.0.rc1.440.g5b76565f74-goog