ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 803 insertions, 0 deletions

diff --git a/drivers/ata/libata-transport.c b/drivers/ata/libata-transport.c
new file mode 100644
index 000000000..95862dc34
--- /dev/null
+++ b/drivers/ata/libata-transport.c
@@ -0,0 +1,803 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright 2008 ioogle, Inc.  All rights reserved.
+ *
+ * Libata transport class.
+ *
+ * The ATA transport class contains common code to deal with ATA HBAs,
+ * an approximated representation of ATA topologies in the driver model,
+ * and various sysfs attributes to expose these topologies and management
+ * interfaces to user-space.
+ *
+ * There are 3 objects defined in this class:
+ * - ata_port
+ * - ata_link
+ * - ata_device
+ * Each port has a link object. Each link can have up to two devices for PATA
+ * and generally one for SATA.
+ * If there is SATA port multiplier [PMP], 15 additional ata_link object are
+ * created.
+ *
+ * These objects are created when the ata host is initialized and when a PMP is
+ * found. They are removed only when the HBA is removed, cleaned before the
+ * error handler runs.
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/blkdev.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <scsi/scsi_transport.h>
+#include <linux/libata.h>
+#include <linux/hdreg.h>
+#include <linux/uaccess.h>
+#include <linux/pm_runtime.h>
+
+#include "libata.h"
+#include "libata-transport.h"
+
+static int ata_tlink_match(struct attribute_container *cont,
+			   struct device *dev);
+static int ata_tdev_match(struct attribute_container *cont,
+			  struct device *dev);
+
+#define tdev_to_device(d)					\
+	container_of((d), struct ata_device, tdev)
+#define transport_class_to_dev(dev)				\
+	tdev_to_device((dev)->parent)
+
+#define tdev_to_link(d)						\
+	container_of((d), struct ata_link, tdev)
+#define transport_class_to_link(dev)				\
+	tdev_to_link((dev)->parent)
+
+#define tdev_to_port(d)						\
+	container_of((d), struct ata_port, tdev)
+#define transport_class_to_port(dev)				\
+	tdev_to_port((dev)->parent)
+
+#define ata_bitfield_name_match(title, table)			\
+static ssize_t							\
+get_ata_##title##_names(u32 table_key, char *buf)		\
+{								\
+	char *prefix = "";					\
+	ssize_t len = 0;					\
+	int i;							\
+								\
+	for (i = 0; i < ARRAY_SIZE(table); i++) {		\
+		if (table[i].value & table_key) {		\
+			len += sprintf(buf + len, "%s%s",	\
+				prefix, table[i].name);		\
+			prefix = ", ";				\
+		}						\
+	}							\
+	len += sprintf(buf + len, "\n");			\
+	return len;						\
+}
+
+#define ata_bitfield_name_search(title, table)			\
+static ssize_t							\
+get_ata_##title##_names(u32 table_key, char *buf)		\
+{								\
+	ssize_t len = 0;					\
+	int i;							\
+								\
+	for (i = 0; i < ARRAY_SIZE(table); i++) {		\
+		if (table[i].value == table_key) {		\
+			len += sprintf(buf + len, "%s",		\
+				table[i].name);			\
+			break;					\
+		}						\
+	}							\
+	len += sprintf(buf + len, "\n");			\
+	return len;						\
+}
+
+static struct {
+	u32		value;
+	char		*name;
+} ata_class_names[] = {
+	{ ATA_DEV_UNKNOWN,		"unknown" },
+	{ ATA_DEV_ATA,			"ata" },
+	{ ATA_DEV_ATA_UNSUP,		"ata" },
+	{ ATA_DEV_ATAPI,		"atapi" },
+	{ ATA_DEV_ATAPI_UNSUP,		"atapi" },
+	{ ATA_DEV_PMP,			"pmp" },
+	{ ATA_DEV_PMP_UNSUP,		"pmp" },
+	{ ATA_DEV_SEMB,			"semb" },
+	{ ATA_DEV_SEMB_UNSUP,		"semb" },
+	{ ATA_DEV_ZAC,			"zac" },
+	{ ATA_DEV_NONE,			"none" }
+};
+ata_bitfield_name_search(class, ata_class_names)
+
+
+static struct {
+	u32		value;
+	char		*name;
+} ata_err_names[] = {
+	{ AC_ERR_DEV,			"DeviceError" },
+	{ AC_ERR_HSM,			"HostStateMachineError" },
+	{ AC_ERR_TIMEOUT,		"Timeout" },
+	{ AC_ERR_MEDIA,			"MediaError" },
+	{ AC_ERR_ATA_BUS,		"BusError" },
+	{ AC_ERR_HOST_BUS,		"HostBusError" },
+	{ AC_ERR_SYSTEM,		"SystemError" },
+	{ AC_ERR_INVALID,		"InvalidArg" },
+	{ AC_ERR_OTHER,			"Unknown" },
+	{ AC_ERR_NODEV_HINT,		"NoDeviceHint" },
+	{ AC_ERR_NCQ,			"NCQError" }
+};
+ata_bitfield_name_match(err, ata_err_names)
+
+static struct {
+	u32		value;
+	char		*name;
+} ata_xfer_names[] = {
+	{ XFER_UDMA_7,			"XFER_UDMA_7" },
+	{ XFER_UDMA_6,			"XFER_UDMA_6" },
+	{ XFER_UDMA_5,			"XFER_UDMA_5" },
+	{ XFER_UDMA_4,			"XFER_UDMA_4" },
+	{ XFER_UDMA_3,			"XFER_UDMA_3" },
+	{ XFER_UDMA_2,			"XFER_UDMA_2" },
+	{ XFER_UDMA_1,			"XFER_UDMA_1" },
+	{ XFER_UDMA_0,			"XFER_UDMA_0" },
+	{ XFER_MW_DMA_4,		"XFER_MW_DMA_4" },
+	{ XFER_MW_DMA_3,		"XFER_MW_DMA_3" },
+	{ XFER_MW_DMA_2,		"XFER_MW_DMA_2" },
+	{ XFER_MW_DMA_1,		"XFER_MW_DMA_1" },
+	{ XFER_MW_DMA_0,		"XFER_MW_DMA_0" },
+	{ XFER_SW_DMA_2,		"XFER_SW_DMA_2" },
+	{ XFER_SW_DMA_1,		"XFER_SW_DMA_1" },
+	{ XFER_SW_DMA_0,		"XFER_SW_DMA_0" },
+	{ XFER_PIO_6,			"XFER_PIO_6" },
+	{ XFER_PIO_5,			"XFER_PIO_5" },
+	{ XFER_PIO_4,			"XFER_PIO_4" },
+	{ XFER_PIO_3,			"XFER_PIO_3" },
+	{ XFER_PIO_2,			"XFER_PIO_2" },
+	{ XFER_PIO_1,			"XFER_PIO_1" },
+	{ XFER_PIO_0,			"XFER_PIO_0" },
+	{ XFER_PIO_SLOW,		"XFER_PIO_SLOW" }
+};
+ata_bitfield_name_search(xfer, ata_xfer_names)
+
+/*
+ * ATA Port attributes
+ */
+#define ata_port_show_simple(field, name, format_string, cast)		\
+static ssize_t								\
+show_ata_port_##name(struct device *dev,				\
+		     struct device_attribute *attr, char *buf)		\
+{									\
+	struct ata_port *ap = transport_class_to_port(dev);		\
+									\
+	return sysfs_emit(buf, format_string, cast ap->field);	        \
+}
+
+#define ata_port_simple_attr(field, name, format_string, type)		\
+	ata_port_show_simple(field, name, format_string, (type))	\
+static DEVICE_ATTR(name, S_IRUGO, show_ata_port_##name, NULL)
+
+ata_port_simple_attr(nr_pmp_links, nr_pmp_links, "%d\n", int);
+ata_port_simple_attr(stats.idle_irq, idle_irq, "%ld\n", unsigned long);
+/* We want the port_no sysfs attibute to start at 1 (ap->port_no starts at 0) */
+ata_port_simple_attr(port_no + 1, port_no, "%u\n", unsigned int);
+
+static const struct attribute *const ata_port_attr_attrs[] = {
+	&dev_attr_nr_pmp_links.attr,
+	&dev_attr_idle_irq.attr,
+	&dev_attr_port_no.attr,
+	NULL
+};
+
+static const struct attribute_group ata_port_attr_group = {
+	.attrs_const = ata_port_attr_attrs,
+};
+
+static DECLARE_TRANSPORT_CLASS(ata_port_class,
+			       "ata_port", NULL, NULL, NULL);
+
+static void ata_tport_release(struct device *dev)
+{
+	struct ata_port *ap = tdev_to_port(dev);
+	ata_host_put(ap->host);
+}
+
+/**
+ * ata_is_port --  check if a struct device represents a ATA port
+ * @dev:	device to check
+ *
+ * Returns:
+ *	%1 if the device represents a ATA Port, %0 else
+ */
+static int ata_is_port(const struct device *dev)
+{
+	return dev->release == ata_tport_release;
+}
+
+static int ata_tport_match(struct attribute_container *cont,
+			   struct device *dev)
+{
+	if (!ata_is_port(dev))
+		return 0;
+	return &ata_scsi_transportt.host_attrs.ac == cont;
+}
+
+/**
+ * ata_tport_delete  --  remove ATA PORT
+ * @ap:	ATA PORT to remove
+ *
+ * Removes the specified ATA PORT.  Remove the associated link as well.
+ */
+void ata_tport_delete(struct ata_port *ap)
+{
+	struct device *dev = &ap->tdev;
+
+	ata_tlink_delete(&ap->link);
+
+	transport_remove_device(dev);
+	device_del(dev);
+	transport_destroy_device(dev);
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(ata_tport_delete);
+
+static const struct device_type ata_port_sas_type = {
+	.name = ATA_PORT_TYPE_NAME,
+};
+
+/** ata_tport_add - initialize a transport ATA port structure
+ *
+ * @parent:	parent device
+ * @ap:		existing ata_port structure
+ *
+ * Initialize a ATA port structure for sysfs.  It will be added to the device
+ * tree below the device specified by @parent which could be a PCI device.
+ *
+ * Returns %0 on success
+ */
+int ata_tport_add(struct device *parent,
+		  struct ata_port *ap)
+{
+	int error;
+	struct device *dev = &ap->tdev;
+
+	device_initialize(dev);
+	if (ap->flags & ATA_FLAG_SAS_HOST)
+		dev->type = &ata_port_sas_type;
+	else
+		dev->type = &ata_port_type;
+
+	dev->parent = parent;
+	ata_host_get(ap->host);
+	dev->release = ata_tport_release;
+	dev_set_name(dev, "ata%d", ap->print_id);
+	transport_setup_device(dev);
+	ata_acpi_bind_port(ap);
+	error = device_add(dev);
+	if (error) {
+		goto tport_err;
+	}
+
+	device_enable_async_suspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_forbid(dev);
+
+	error = transport_add_device(dev);
+	if (error)
+		goto tport_transport_add_err;
+	transport_configure_device(dev);
+
+	error = ata_tlink_add(&ap->link);
+	if (error) {
+		goto tport_link_err;
+	}
+	return 0;
+
+ tport_link_err:
+	transport_remove_device(dev);
+ tport_transport_add_err:
+	device_del(dev);
+
+ tport_err:
+	transport_destroy_device(dev);
+	put_device(dev);
+	return error;
+}
+EXPORT_SYMBOL_GPL(ata_tport_add);
+
+/**
+ *     ata_port_classify - determine device type based on ATA-spec signature
+ *     @ap: ATA port device on which the classification should be run
+ *     @tf: ATA taskfile register set for device to be identified
+ *
+ *     A wrapper around ata_dev_classify() to provide additional logging
+ *
+ *     RETURNS:
+ *     Device type, %ATA_DEV_ATA, %ATA_DEV_ATAPI, %ATA_DEV_PMP,
+ *     %ATA_DEV_ZAC, or %ATA_DEV_UNKNOWN the event of failure.
+ */
+unsigned int ata_port_classify(struct ata_port *ap,
+			       const struct ata_taskfile *tf)
+{
+	int i;
+	unsigned int class = ata_dev_classify(tf);
+
+	/* Start with index '1' to skip the 'unknown' entry */
+	for (i = 1; i < ARRAY_SIZE(ata_class_names); i++) {
+		if (ata_class_names[i].value == class) {
+			ata_port_dbg(ap, "found %s device by sig\n",
+				     ata_class_names[i].name);
+			return class;
+		}
+	}
+
+	ata_port_info(ap, "found unknown device (class %u)\n", class);
+	return class;
+}
+EXPORT_SYMBOL_GPL(ata_port_classify);
+
+/*
+ * ATA device attributes
+ */
+
+#define ata_dev_show_class(title, field)				\
+static ssize_t								\
+show_ata_dev_##field(struct device *dev,				\
+		     struct device_attribute *attr, char *buf)		\
+{									\
+	struct ata_device *ata_dev = transport_class_to_dev(dev);	\
+									\
+	return get_ata_##title##_names(ata_dev->field, buf);		\
+}
+
+#define ata_dev_attr(title, field)					\
+	ata_dev_show_class(title, field)				\
+static DEVICE_ATTR(field, S_IRUGO, show_ata_dev_##field, NULL)
+
+ata_dev_attr(class, class);
+ata_dev_attr(xfer, pio_mode);
+ata_dev_attr(xfer, dma_mode);
+ata_dev_attr(xfer, xfer_mode);
+
+
+#define ata_dev_show_simple(field, format_string, cast)			\
+static ssize_t								\
+show_ata_dev_##field(struct device *dev,				\
+		     struct device_attribute *attr, char *buf)		\
+{									\
+	struct ata_device *ata_dev = transport_class_to_dev(dev);	\
+									\
+	return sysfs_emit(buf, format_string, cast ata_dev->field);	\
+}
+
+#define ata_dev_simple_attr(field, format_string, type)		\
+	ata_dev_show_simple(field, format_string, (type))	\
+	static DEVICE_ATTR(field, S_IRUGO,			\
+		   show_ata_dev_##field, NULL)
+
+ata_dev_simple_attr(spdn_cnt, "%d\n", int);
+
+struct ata_show_ering_arg {
+	char* buf;
+	int written;
+};
+
+static int ata_show_ering(struct ata_ering_entry *ent, void *void_arg)
+{
+	struct ata_show_ering_arg* arg = void_arg;
+	u64 seconds;
+	u32 rem;
+
+	seconds = div_u64_rem(ent->timestamp, HZ, &rem);
+	arg->written += sprintf(arg->buf + arg->written,
+				"[%5llu.%09lu]", seconds,
+				rem * NSEC_PER_SEC / HZ);
+	arg->written += get_ata_err_names(ent->err_mask,
+					  arg->buf + arg->written);
+	return 0;
+}
+
+static ssize_t
+show_ata_dev_ering(struct device *dev,
+		   struct device_attribute *attr, char *buf)
+{
+	struct ata_device *ata_dev = transport_class_to_dev(dev);
+	struct ata_show_ering_arg arg = { buf, 0 };
+
+	ata_ering_map(&ata_dev->ering, ata_show_ering, &arg);
+	return arg.written;
+}
+
+
+static DEVICE_ATTR(ering, S_IRUGO, show_ata_dev_ering, NULL);
+
+static ssize_t
+show_ata_dev_id(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct ata_device *ata_dev = transport_class_to_dev(dev);
+	int written = 0, i = 0;
+
+	if (ata_dev->class == ATA_DEV_PMP)
+		return 0;
+	for(i=0;i<ATA_ID_WORDS;i++)  {
+		written += scnprintf(buf+written, 20, "%04x%c",
+				    ata_dev->id[i],
+				    ((i+1) & 7) ? ' ' : '\n');
+	}
+	return written;
+}
+
+static DEVICE_ATTR(id, S_IRUGO, show_ata_dev_id, NULL);
+
+static ssize_t
+show_ata_dev_gscr(struct device *dev,
+		  struct device_attribute *attr, char *buf)
+{
+	struct ata_device *ata_dev = transport_class_to_dev(dev);
+	int written = 0, i = 0;
+
+	if (ata_dev->class != ATA_DEV_PMP)
+		return 0;
+	for(i=0;i<SATA_PMP_GSCR_DWORDS;i++)  {
+		written += scnprintf(buf+written, 20, "%08x%c",
+				    ata_dev->gscr[i],
+				    ((i+1) & 3) ? ' ' : '\n');
+	}
+	if (SATA_PMP_GSCR_DWORDS & 3)
+		buf[written-1] = '\n';
+	return written;
+}
+
+static DEVICE_ATTR(gscr, S_IRUGO, show_ata_dev_gscr, NULL);
+
+static ssize_t
+show_ata_dev_trim(struct device *dev,
+		  struct device_attribute *attr, char *buf)
+{
+	struct ata_device *ata_dev = transport_class_to_dev(dev);
+	unsigned char *mode;
+
+	if (!ata_id_has_trim(ata_dev->id))
+		mode = "unsupported";
+	else if (ata_dev->quirks & ATA_QUIRK_NOTRIM)
+		mode = "forced_unsupported";
+	else if (ata_dev->quirks & ATA_QUIRK_NO_NCQ_TRIM)
+		mode = "forced_unqueued";
+	else if (ata_fpdma_dsm_supported(ata_dev))
+		mode = "queued";
+	else
+		mode = "unqueued";
+
+	return scnprintf(buf, 20, "%s\n", mode);
+}
+
+static DEVICE_ATTR(trim, S_IRUGO, show_ata_dev_trim, NULL);
+
+static const struct attribute *const ata_device_attr_attrs[] = {
+	&dev_attr_class.attr,
+	&dev_attr_pio_mode.attr,
+	&dev_attr_dma_mode.attr,
+	&dev_attr_xfer_mode.attr,
+	&dev_attr_spdn_cnt.attr,
+	&dev_attr_ering.attr,
+	&dev_attr_id.attr,
+	&dev_attr_gscr.attr,
+	&dev_attr_trim.attr,
+	NULL
+};
+
+static const struct attribute_group ata_device_attr_group = {
+	.attrs_const = ata_device_attr_attrs,
+};
+
+static DECLARE_TRANSPORT_CLASS(ata_dev_class,
+			       "ata_device", NULL, NULL, NULL);
+
+static void ata_tdev_release(struct device *dev)
+{
+}
+
+/**
+ * ata_is_ata_dev  --  check if a struct device represents a ATA device
+ * @dev:	device to check
+ *
+ * Returns:
+ *	true if the device represents a ATA device, false otherwise
+ */
+static bool ata_is_ata_dev(const struct device *dev)
+{
+	return dev->release == ata_tdev_release;
+}
+
+/**
+ * ata_tdev_free  --  free an ATA transport device
+ * @dev:	struct ata_device owning the transport device to free
+ *
+ * Free the ATA transport device for the specified ATA device.
+ *
+ * Note:
+ *   This function must only be called for a ATA transport device that has not
+ *   yet successfully been added using ata_tdev_add().
+ */
+static void ata_tdev_free(struct ata_device *dev)
+{
+	transport_destroy_device(&dev->tdev);
+	put_device(&dev->tdev);
+}
+
+/**
+ * ata_tdev_delete  --  remove an ATA transport device
+ * @ata_dev:	struct ata_device owning the transport device to delete
+ *
+ * Removes the ATA transport device for the specified ATA device.
+ */
+static void ata_tdev_delete(struct ata_device *ata_dev)
+{
+	struct device *dev = &ata_dev->tdev;
+
+	transport_remove_device(dev);
+	device_del(dev);
+	ata_tdev_free(ata_dev);
+}
+
+/**
+ * ata_tdev_add  --  initialize an ATA transport device
+ * @ata_dev:	struct ata_device owning the transport device to add
+ *
+ * Initialize an ATA transport device for sysfs.  It will be added in the
+ * device tree below the ATA link device it belongs to.
+ *
+ * Returns %0 on success and a negative error code on error.
+ */
+static int ata_tdev_add(struct ata_device *ata_dev)
+{
+	struct device *dev = &ata_dev->tdev;
+	struct ata_link *link = ata_dev->link;
+	struct ata_port *ap = link->ap;
+	int error;
+
+	device_initialize(dev);
+	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);
+	else
+		dev_set_name(dev, "dev%d.%d.0", ap->print_id, link->pmp);
+
+	transport_setup_device(dev);
+	ata_acpi_bind_dev(ata_dev);
+	error = device_add(dev);
+	if (error) {
+		ata_tdev_free(ata_dev);
+		return error;
+	}
+
+	error = transport_add_device(dev);
+	if (error) {
+		device_del(dev);
+		ata_tdev_free(ata_dev);
+		return error;
+	}
+
+	transport_configure_device(dev);
+	return 0;
+}
+
+/*
+ * ATA link attributes
+ */
+static int noop(int x)
+{
+	return x;
+}
+
+#define ata_link_show_linkspeed(field, format)			\
+static ssize_t							\
+show_ata_link_##field(struct device *dev,			\
+		      struct device_attribute *attr, char *buf)	\
+{								\
+	struct ata_link *link = transport_class_to_link(dev);	\
+								\
+	return sprintf(buf, "%s\n",				\
+		       sata_spd_string(format(link->field)));	\
+}
+
+#define ata_link_linkspeed_attr(field, format)			\
+	ata_link_show_linkspeed(field, format)			\
+static DEVICE_ATTR(field, 0444, show_ata_link_##field, NULL)
+
+ata_link_linkspeed_attr(hw_sata_spd_limit, fls);
+ata_link_linkspeed_attr(sata_spd_limit, fls);
+ata_link_linkspeed_attr(sata_spd, noop);
+
+static const struct attribute *const ata_link_attr_attrs[] = {
+	&dev_attr_hw_sata_spd_limit.attr,
+	&dev_attr_sata_spd_limit.attr,
+	&dev_attr_sata_spd.attr,
+	NULL
+};
+
+static const struct attribute_group ata_link_attr_group = {
+	.attrs_const = ata_link_attr_attrs,
+};
+
+static DECLARE_TRANSPORT_CLASS(ata_link_class,
+		"ata_link", NULL, NULL, NULL);
+
+static void ata_tlink_release(struct device *dev)
+{
+}
+
+/**
+ * ata_is_link --  check if a struct device represents a ATA link
+ * @dev:	device to check
+ *
+ * Returns:
+ *	true if the device represents a ATA link, false otherwise
+ */
+static bool ata_is_link(const struct device *dev)
+{
+	return dev->release == ata_tlink_release;
+}
+
+/**
+ * ata_tlink_delete  --  remove an ATA link transport device
+ * @link:	struct ata_link owning the link transport device to remove
+ *
+ * Removes the link transport device of the specified ATA link. This also
+ * removes the ATA device(s) associated with the link as well.
+ */
+void ata_tlink_delete(struct ata_link *link)
+{
+	struct device *dev = &link->tdev;
+	struct ata_device *ata_dev;
+
+	ata_for_each_dev(ata_dev, link, ALL) {
+		ata_tdev_delete(ata_dev);
+	}
+
+	transport_remove_device(dev);
+	device_del(dev);
+	transport_destroy_device(dev);
+	put_device(dev);
+}
+
+/**
+ * ata_tlink_add  --  initialize an ATA link transport device
+ * @link:	struct ata_link owning the link transport device to initialize
+ *
+ * Initialize an ATA link transport device for sysfs. It will be added in the
+ * device tree below the ATA port it belongs to.
+ *
+ * Returns %0 on success and a negative error code on error.
+ */
+int ata_tlink_add(struct ata_link *link)
+{
+	struct device *dev = &link->tdev;
+	struct ata_port *ap = link->ap;
+	struct ata_device *ata_dev;
+	int error;
+
+	device_initialize(dev);
+	dev->parent = &ap->tdev;
+	dev->release = ata_tlink_release;
+	if (ata_is_host_link(link))
+		dev_set_name(dev, "link%d", ap->print_id);
+	else
+		dev_set_name(dev, "link%d.%d", ap->print_id, link->pmp);
+
+	transport_setup_device(dev);
+
+	error = device_add(dev);
+	if (error)
+		goto tlink_err;
+
+	error = transport_add_device(dev);
+	if (error)
+		goto tlink_transport_err;
+	transport_configure_device(dev);
+
+	ata_for_each_dev(ata_dev, link, ALL) {
+		error = ata_tdev_add(ata_dev);
+		if (error)
+			goto tlink_dev_err;
+	}
+	return 0;
+ tlink_dev_err:
+	while (--ata_dev >= link->device)
+		ata_tdev_delete(ata_dev);
+	transport_remove_device(dev);
+ tlink_transport_err:
+	device_del(dev);
+ tlink_err:
+	transport_destroy_device(dev);
+	put_device(dev);
+	return error;
+}
+
+struct scsi_transport_template ata_scsi_transportt = {
+	.eh_strategy_handler	= ata_scsi_error,
+	.user_scan		= ata_scsi_user_scan,
+
+	.host_attrs.ac.class	= &ata_port_class.class,
+	.host_attrs.ac.grp	= &ata_port_attr_group,
+	.host_attrs.ac.match	= ata_tport_match,
+};
+
+static struct transport_container ata_link_attr_cont = {
+	.ac.class	= &ata_link_class.class,
+	.ac.grp		= &ata_link_attr_group,
+	.ac.match	= ata_tlink_match,
+};
+
+static struct transport_container ata_dev_attr_cont = {
+	.ac.class	= &ata_dev_class.class,
+	.ac.grp		= &ata_device_attr_group,
+	.ac.match	= ata_tdev_match,
+};
+
+static int ata_tlink_match(struct attribute_container *cont,
+			   struct device *dev)
+{
+	if (!ata_is_link(dev))
+		return 0;
+
+	return &ata_link_attr_cont.ac == cont;
+}
+
+static int ata_tdev_match(struct attribute_container *cont,
+			  struct device *dev)
+{
+	if (!ata_is_ata_dev(dev))
+		return 0;
+
+	return &ata_dev_attr_cont.ac == cont;
+}
+
+/*
+ * Setup / Teardown code
+ */
+
+__init int libata_transport_init(void)
+{
+	int error;
+
+	error = transport_class_register(&ata_link_class);
+	if (error)
+		goto out_unregister_transport;
+	error = transport_class_register(&ata_port_class);
+	if (error)
+		goto out_unregister_link;
+	error = transport_class_register(&ata_dev_class);
+	if (error)
+		goto out_unregister_port;
+
+	transport_container_register(&ata_scsi_transportt.host_attrs);
+	transport_container_register(&ata_link_attr_cont);
+	transport_container_register(&ata_dev_attr_cont);
+
+	return 0;
+
+ out_unregister_port:
+	transport_class_unregister(&ata_port_class);
+ out_unregister_link:
+	transport_class_unregister(&ata_link_class);
+ out_unregister_transport:
+	return error;
+
+}
+
+void __exit libata_transport_exit(void)
+{
+	transport_container_unregister(&ata_scsi_transportt.host_attrs);
+	transport_container_unregister(&ata_link_attr_cont);
+	transport_container_unregister(&ata_dev_attr_cont);
+
+	transport_class_unregister(&ata_link_class);
+	transport_class_unregister(&ata_port_class);
+	transport_class_unregister(&ata_dev_class);
+}