Patch "libata: transport: Remove circular dependency at free time" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

libata: transport: Remove circular dependency at free time

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
libata-transport-remove-circular-dependency-at-free-time.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Gwendal Grignou <[email protected]>
Date: Fri, 3 Mar 2017 09:00:09 -0800
Subject: libata: transport: Remove circular dependency at free time

From: Gwendal Grignou <[email protected]>

[ Upstream commit d85fc67dd11e9a32966140677d4d6429ca540b25 ]

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 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's device_del().

---
 drivers/ata/libata-transport.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

@@ -224,7 +224,6 @@ static DECLARE_TRANSPORT_CLASS(ata_port_
 
 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_
 
 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_c
 
 static void ata_tdev_release(struct device *dev)
 {
-	put_device(dev->parent);
 }
 
 /**

@@ -662,7 +659,7 @@ static int ata_tdev_add(struct ata_devic
 	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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/libata-transport-remove-circular-dependency-at-free-time.patch