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Subject[PATCH 3.18 29/35] libata: transport: Remove circular dependency at free time
Date
3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gwendal Grignou <gwendal@chromium.org>


[ 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().

Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Tested-by: Matthew Whitehead <tedheadster@gmail.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/ata/libata-transport.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

--- a/drivers/ata/libata-transport.c
+++ b/drivers/ata/libata-transport.c
@@ -223,7 +223,6 @@ static DECLARE_TRANSPORT_CLASS(ata_port_

static void ata_tport_release(struct device *dev)
{
- put_device(dev->parent);
}

/**
@@ -283,7 +282,7 @@ 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);
@@ -347,7 +346,6 @@ static DECLARE_TRANSPORT_CLASS(ata_link_

static void ata_tlink_release(struct device *dev)
{
- put_device(dev->parent);
}

/**
@@ -409,7 +407,7 @@ 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);
@@ -587,7 +585,6 @@ static DECLARE_TRANSPORT_CLASS(ata_dev_c

static void ata_tdev_release(struct device *dev)
{
- put_device(dev->parent);
}

/**
@@ -660,7 +657,7 @@ 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);

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