Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 742 insertions, 0 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
new file mode 100644
index 000000000..8b825364b
--- /dev/null
+++ b/drivers/scsi/hosts.c
@@ -0,0 +1,742 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  hosts.c Copyright (C) 1992 Drew Eckhardt
+ *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
+ *          Copyright (C) 2002-2003 Christoph Hellwig
+ *
+ *  mid to lowlevel SCSI driver interface
+ *      Initial versions: Drew Eckhardt
+ *      Subsequent revisions: Eric Youngdale
+ *
+ *  <drew@colorado.edu>
+ *
+ *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
+ *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
+ *     August 4, 1999 Fred Lewis, Intel DuPont
+ *
+ *  Updated to reflect the new initialization scheme for the higher 
+ *  level of scsi drivers (sd/sr/st)
+ *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
+ *
+ *  Restructured scsi_host lists and associated functions.
+ *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
+ */
+
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/transport_class.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/idr.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_transport.h>
+#include <scsi/scsi_cmnd.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+
+static int shost_eh_deadline = -1;
+
+module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(eh_deadline,
+		 "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");
+
+static DEFINE_IDA(host_index_ida);
+
+
+static void scsi_host_cls_release(struct device *dev)
+{
+	put_device(&class_to_shost(dev)->shost_gendev);
+}
+
+static struct class shost_class = {
+	.name		= "scsi_host",
+	.dev_release	= scsi_host_cls_release,
+	.dev_groups	= scsi_shost_groups,
+};
+
+/**
+ *	scsi_host_set_state - Take the given host through the host state model.
+ *	@shost:	scsi host to change the state of.
+ *	@state:	state to change to.
+ *
+ *	Returns zero if unsuccessful or an error if the requested
+ *	transition is illegal.
+ **/
+int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
+{
+	enum scsi_host_state oldstate = shost->shost_state;
+
+	if (state == oldstate)
+		return 0;
+
+	switch (state) {
+	case SHOST_CREATED:
+		/* There are no legal states that come back to
+		 * created.  This is the manually initialised start
+		 * state */
+		goto illegal;
+
+	case SHOST_RUNNING:
+		switch (oldstate) {
+		case SHOST_CREATED:
+		case SHOST_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_RECOVERY:
+		switch (oldstate) {
+		case SHOST_RUNNING:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_CANCEL:
+		switch (oldstate) {
+		case SHOST_CREATED:
+		case SHOST_RUNNING:
+		case SHOST_CANCEL_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_DEL:
+		switch (oldstate) {
+		case SHOST_CANCEL:
+		case SHOST_DEL_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_CANCEL_RECOVERY:
+		switch (oldstate) {
+		case SHOST_CANCEL:
+		case SHOST_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_DEL_RECOVERY:
+		switch (oldstate) {
+		case SHOST_CANCEL_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+	}
+	shost->shost_state = state;
+	return 0;
+
+ illegal:
+	SCSI_LOG_ERROR_RECOVERY(1,
+				shost_printk(KERN_ERR, shost,
+					     "Illegal host state transition"
+					     "%s->%s\n",
+					     scsi_host_state_name(oldstate),
+					     scsi_host_state_name(state)));
+	return -EINVAL;
+}
+
+/**
+ * scsi_remove_host - remove a scsi host
+ * @shost:	a pointer to a scsi host to remove
+ **/
+void scsi_remove_host(struct Scsi_Host *shost)
+{
+	unsigned long flags;
+
+	mutex_lock(&shost->scan_mutex);
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (scsi_host_set_state(shost, SHOST_CANCEL))
+		if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
+			spin_unlock_irqrestore(shost->host_lock, flags);
+			mutex_unlock(&shost->scan_mutex);
+			return;
+		}
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	scsi_autopm_get_host(shost);
+	flush_workqueue(shost->tmf_work_q);
+	scsi_forget_host(shost);
+	mutex_unlock(&shost->scan_mutex);
+	scsi_proc_host_rm(shost);
+	scsi_proc_hostdir_rm(shost->hostt);
+
+	/*
+	 * New SCSI devices cannot be attached anymore because of the SCSI host
+	 * state so drop the tag set refcnt. Wait until the tag set refcnt drops
+	 * to zero because .exit_cmd_priv implementations may need the host
+	 * pointer.
+	 */
+	kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
+	wait_for_completion(&shost->tagset_freed);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (scsi_host_set_state(shost, SHOST_DEL))
+		BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	transport_unregister_device(&shost->shost_gendev);
+	device_unregister(&shost->shost_dev);
+	device_del(&shost->shost_gendev);
+}
+EXPORT_SYMBOL(scsi_remove_host);
+
+/**
+ * scsi_add_host_with_dma - add a scsi host with dma device
+ * @shost:	scsi host pointer to add
+ * @dev:	a struct device of type scsi class
+ * @dma_dev:	dma device for the host
+ *
+ * Note: You rarely need to worry about this unless you're in a
+ * virtualised host environments, so use the simpler scsi_add_host()
+ * function instead.
+ *
+ * Return value: 
+ * 	0 on success / != 0 for error
+ **/
+int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
+			   struct device *dma_dev)
+{
+	struct scsi_host_template *sht = shost->hostt;
+	int error = -EINVAL;
+
+	shost_printk(KERN_INFO, shost, "%s\n",
+			sht->info ? sht->info(shost) : sht->name);
+
+	if (!shost->can_queue) {
+		shost_printk(KERN_ERR, shost,
+			     "can_queue = 0 no longer supported\n");
+		goto fail;
+	}
+
+	/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
+	shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
+				   shost->can_queue);
+
+	error = scsi_init_sense_cache(shost);
+	if (error)
+		goto fail;
+
+	if (!shost->shost_gendev.parent)
+		shost->shost_gendev.parent = dev ? dev : &platform_bus;
+	if (!dma_dev)
+		dma_dev = shost->shost_gendev.parent;
+
+	shost->dma_dev = dma_dev;
+
+	if (dma_dev->dma_mask) {
+		shost->max_sectors = min_t(unsigned int, shost->max_sectors,
+				dma_max_mapping_size(dma_dev) >> SECTOR_SHIFT);
+	}
+
+	error = scsi_mq_setup_tags(shost);
+	if (error)
+		goto fail;
+
+	kref_init(&shost->tagset_refcnt);
+	init_completion(&shost->tagset_freed);
+
+	/*
+	 * Increase usage count temporarily here so that calling
+	 * scsi_autopm_put_host() will trigger runtime idle if there is
+	 * nothing else preventing suspending the device.
+	 */
+	pm_runtime_get_noresume(&shost->shost_gendev);
+	pm_runtime_set_active(&shost->shost_gendev);
+	pm_runtime_enable(&shost->shost_gendev);
+	device_enable_async_suspend(&shost->shost_gendev);
+
+	error = device_add(&shost->shost_gendev);
+	if (error)
+		goto out_disable_runtime_pm;
+
+	scsi_host_set_state(shost, SHOST_RUNNING);
+	get_device(shost->shost_gendev.parent);
+
+	device_enable_async_suspend(&shost->shost_dev);
+
+	get_device(&shost->shost_gendev);
+	error = device_add(&shost->shost_dev);
+	if (error)
+		goto out_del_gendev;
+
+	if (shost->transportt->host_size) {
+		shost->shost_data = kzalloc(shost->transportt->host_size,
+					 GFP_KERNEL);
+		if (shost->shost_data == NULL) {
+			error = -ENOMEM;
+			goto out_del_dev;
+		}
+	}
+
+	if (shost->transportt->create_work_queue) {
+		snprintf(shost->work_q_name, sizeof(shost->work_q_name),
+			 "scsi_wq_%d", shost->host_no);
+		shost->work_q = alloc_workqueue("%s",
+			WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
+			1, shost->work_q_name);
+
+		if (!shost->work_q) {
+			error = -EINVAL;
+			goto out_del_dev;
+		}
+	}
+
+	error = scsi_sysfs_add_host(shost);
+	if (error)
+		goto out_del_dev;
+
+	scsi_proc_host_add(shost);
+	scsi_autopm_put_host(shost);
+	return error;
+
+	/*
+	 * Any host allocation in this function will be freed in
+	 * scsi_host_dev_release().
+	 */
+ out_del_dev:
+	device_del(&shost->shost_dev);
+ out_del_gendev:
+	/*
+	 * Host state is SHOST_RUNNING so we have to explicitly release
+	 * ->shost_dev.
+	 */
+	put_device(&shost->shost_dev);
+	device_del(&shost->shost_gendev);
+ out_disable_runtime_pm:
+	device_disable_async_suspend(&shost->shost_gendev);
+	pm_runtime_disable(&shost->shost_gendev);
+	pm_runtime_set_suspended(&shost->shost_gendev);
+	pm_runtime_put_noidle(&shost->shost_gendev);
+	kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
+ fail:
+	return error;
+}
+EXPORT_SYMBOL(scsi_add_host_with_dma);
+
+static void scsi_host_dev_release(struct device *dev)
+{
+	struct Scsi_Host *shost = dev_to_shost(dev);
+	struct device *parent = dev->parent;
+
+	/* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
+	rcu_barrier();
+
+	if (shost->tmf_work_q)
+		destroy_workqueue(shost->tmf_work_q);
+	if (shost->ehandler)
+		kthread_stop(shost->ehandler);
+	if (shost->work_q)
+		destroy_workqueue(shost->work_q);
+
+	if (shost->shost_state == SHOST_CREATED) {
+		/*
+		 * Free the shost_dev device name here if scsi_host_alloc()
+		 * and scsi_host_put() have been called but neither
+		 * scsi_host_add() nor scsi_host_remove() has been called.
+		 * This avoids that the memory allocated for the shost_dev
+		 * name is leaked.
+		 */
+		kfree(dev_name(&shost->shost_dev));
+	}
+
+	kfree(shost->shost_data);
+
+	ida_free(&host_index_ida, shost->host_no);
+
+	if (shost->shost_state != SHOST_CREATED)
+		put_device(parent);
+	kfree(shost);
+}
+
+static struct device_type scsi_host_type = {
+	.name =		"scsi_host",
+	.release =	scsi_host_dev_release,
+};
+
+/**
+ * scsi_host_alloc - register a scsi host adapter instance.
+ * @sht:	pointer to scsi host template
+ * @privsize:	extra bytes to allocate for driver
+ *
+ * Note:
+ * 	Allocate a new Scsi_Host and perform basic initialization.
+ * 	The host is not published to the scsi midlayer until scsi_add_host
+ * 	is called.
+ *
+ * Return value:
+ * 	Pointer to a new Scsi_Host
+ **/
+struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
+{
+	struct Scsi_Host *shost;
+	int index;
+
+	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
+	if (!shost)
+		return NULL;
+
+	shost->host_lock = &shost->default_lock;
+	spin_lock_init(shost->host_lock);
+	shost->shost_state = SHOST_CREATED;
+	INIT_LIST_HEAD(&shost->__devices);
+	INIT_LIST_HEAD(&shost->__targets);
+	INIT_LIST_HEAD(&shost->eh_abort_list);
+	INIT_LIST_HEAD(&shost->eh_cmd_q);
+	INIT_LIST_HEAD(&shost->starved_list);
+	init_waitqueue_head(&shost->host_wait);
+	mutex_init(&shost->scan_mutex);
+
+	index = ida_alloc(&host_index_ida, GFP_KERNEL);
+	if (index < 0) {
+		kfree(shost);
+		return NULL;
+	}
+	shost->host_no = index;
+
+	shost->dma_channel = 0xff;
+
+	/* These three are default values which can be overridden */
+	shost->max_channel = 0;
+	shost->max_id = 8;
+	shost->max_lun = 8;
+
+	/* Give each shost a default transportt */
+	shost->transportt = &blank_transport_template;
+
+	/*
+	 * All drivers right now should be able to handle 12 byte
+	 * commands.  Every so often there are requests for 16 byte
+	 * commands, but individual low-level drivers need to certify that
+	 * they actually do something sensible with such commands.
+	 */
+	shost->max_cmd_len = 12;
+	shost->hostt = sht;
+	shost->this_id = sht->this_id;
+	shost->can_queue = sht->can_queue;
+	shost->sg_tablesize = sht->sg_tablesize;
+	shost->sg_prot_tablesize = sht->sg_prot_tablesize;
+	shost->cmd_per_lun = sht->cmd_per_lun;
+	shost->no_write_same = sht->no_write_same;
+	shost->host_tagset = sht->host_tagset;
+
+	if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
+		shost->eh_deadline = -1;
+	else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
+		shost_printk(KERN_WARNING, shost,
+			     "eh_deadline %u too large, setting to %u\n",
+			     shost_eh_deadline, INT_MAX / HZ);
+		shost->eh_deadline = INT_MAX;
+	} else
+		shost->eh_deadline = shost_eh_deadline * HZ;
+
+	if (sht->supported_mode == MODE_UNKNOWN)
+		/* means we didn't set it ... default to INITIATOR */
+		shost->active_mode = MODE_INITIATOR;
+	else
+		shost->active_mode = sht->supported_mode;
+
+	if (sht->max_host_blocked)
+		shost->max_host_blocked = sht->max_host_blocked;
+	else
+		shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
+
+	/*
+	 * If the driver imposes no hard sector transfer limit, start at
+	 * machine infinity initially.
+	 */
+	if (sht->max_sectors)
+		shost->max_sectors = sht->max_sectors;
+	else
+		shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
+
+	if (sht->max_segment_size)
+		shost->max_segment_size = sht->max_segment_size;
+	else
+		shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
+
+	/*
+	 * assume a 4GB boundary, if not set
+	 */
+	if (sht->dma_boundary)
+		shost->dma_boundary = sht->dma_boundary;
+	else
+		shost->dma_boundary = 0xffffffff;
+
+	if (sht->virt_boundary_mask)
+		shost->virt_boundary_mask = sht->virt_boundary_mask;
+
+	device_initialize(&shost->shost_gendev);
+	dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
+	shost->shost_gendev.bus = &scsi_bus_type;
+	shost->shost_gendev.type = &scsi_host_type;
+	scsi_enable_async_suspend(&shost->shost_gendev);
+
+	device_initialize(&shost->shost_dev);
+	shost->shost_dev.parent = &shost->shost_gendev;
+	shost->shost_dev.class = &shost_class;
+	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
+	shost->shost_dev.groups = sht->shost_groups;
+
+	shost->ehandler = kthread_run(scsi_error_handler, shost,
+			"scsi_eh_%d", shost->host_no);
+	if (IS_ERR(shost->ehandler)) {
+		shost_printk(KERN_WARNING, shost,
+			"error handler thread failed to spawn, error = %ld\n",
+			PTR_ERR(shost->ehandler));
+		shost->ehandler = NULL;
+		goto fail;
+	}
+
+	shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
+					WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
+					   1, shost->host_no);
+	if (!shost->tmf_work_q) {
+		shost_printk(KERN_WARNING, shost,
+			     "failed to create tmf workq\n");
+		goto fail;
+	}
+	scsi_proc_hostdir_add(shost->hostt);
+	return shost;
+ fail:
+	/*
+	 * Host state is still SHOST_CREATED and that is enough to release
+	 * ->shost_gendev. scsi_host_dev_release() will free
+	 * dev_name(&shost->shost_dev).
+	 */
+	put_device(&shost->shost_gendev);
+
+	return NULL;
+}
+EXPORT_SYMBOL(scsi_host_alloc);
+
+static int __scsi_host_match(struct device *dev, const void *data)
+{
+	struct Scsi_Host *p;
+	const unsigned int *hostnum = data;
+
+	p = class_to_shost(dev);
+	return p->host_no == *hostnum;
+}
+
+/**
+ * scsi_host_lookup - get a reference to a Scsi_Host by host no
+ * @hostnum:	host number to locate
+ *
+ * Return value:
+ *	A pointer to located Scsi_Host or NULL.
+ *
+ *	The caller must do a scsi_host_put() to drop the reference
+ *	that scsi_host_get() took. The put_device() below dropped
+ *	the reference from class_find_device().
+ **/
+struct Scsi_Host *scsi_host_lookup(unsigned int hostnum)
+{
+	struct device *cdev;
+	struct Scsi_Host *shost = NULL;
+
+	cdev = class_find_device(&shost_class, NULL, &hostnum,
+				 __scsi_host_match);
+	if (cdev) {
+		shost = scsi_host_get(class_to_shost(cdev));
+		put_device(cdev);
+	}
+	return shost;
+}
+EXPORT_SYMBOL(scsi_host_lookup);
+
+/**
+ * scsi_host_get - inc a Scsi_Host ref count
+ * @shost:	Pointer to Scsi_Host to inc.
+ **/
+struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
+{
+	if ((shost->shost_state == SHOST_DEL) ||
+		!get_device(&shost->shost_gendev))
+		return NULL;
+	return shost;
+}
+EXPORT_SYMBOL(scsi_host_get);
+
+static bool scsi_host_check_in_flight(struct request *rq, void *data)
+{
+	int *count = data;
+	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+
+	if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
+		(*count)++;
+
+	return true;
+}
+
+/**
+ * scsi_host_busy - Return the host busy counter
+ * @shost:	Pointer to Scsi_Host to inc.
+ **/
+int scsi_host_busy(struct Scsi_Host *shost)
+{
+	int cnt = 0;
+
+	blk_mq_tagset_busy_iter(&shost->tag_set,
+				scsi_host_check_in_flight, &cnt);
+	return cnt;
+}
+EXPORT_SYMBOL(scsi_host_busy);
+
+/**
+ * scsi_host_put - dec a Scsi_Host ref count
+ * @shost:	Pointer to Scsi_Host to dec.
+ **/
+void scsi_host_put(struct Scsi_Host *shost)
+{
+	put_device(&shost->shost_gendev);
+}
+EXPORT_SYMBOL(scsi_host_put);
+
+int scsi_init_hosts(void)
+{
+	return class_register(&shost_class);
+}
+
+void scsi_exit_hosts(void)
+{
+	class_unregister(&shost_class);
+	ida_destroy(&host_index_ida);
+}
+
+int scsi_is_host_device(const struct device *dev)
+{
+	return dev->type == &scsi_host_type;
+}
+EXPORT_SYMBOL(scsi_is_host_device);
+
+/**
+ * scsi_queue_work - Queue work to the Scsi_Host workqueue.
+ * @shost:	Pointer to Scsi_Host.
+ * @work:	Work to queue for execution.
+ *
+ * Return value:
+ * 	1 - work queued for execution
+ *	0 - work is already queued
+ *	-EINVAL - work queue doesn't exist
+ **/
+int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
+{
+	if (unlikely(!shost->work_q)) {
+		shost_printk(KERN_ERR, shost,
+			"ERROR: Scsi host '%s' attempted to queue scsi-work, "
+			"when no workqueue created.\n", shost->hostt->name);
+		dump_stack();
+
+		return -EINVAL;
+	}
+
+	return queue_work(shost->work_q, work);
+}
+EXPORT_SYMBOL_GPL(scsi_queue_work);
+
+/**
+ * scsi_flush_work - Flush a Scsi_Host's workqueue.
+ * @shost:	Pointer to Scsi_Host.
+ **/
+void scsi_flush_work(struct Scsi_Host *shost)
+{
+	if (!shost->work_q) {
+		shost_printk(KERN_ERR, shost,
+			"ERROR: Scsi host '%s' attempted to flush scsi-work, "
+			"when no workqueue created.\n", shost->hostt->name);
+		dump_stack();
+		return;
+	}
+
+	flush_workqueue(shost->work_q);
+}
+EXPORT_SYMBOL_GPL(scsi_flush_work);
+
+static bool complete_all_cmds_iter(struct request *rq, void *data)
+{
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
+	enum scsi_host_status status = *(enum scsi_host_status *)data;
+
+	scsi_dma_unmap(scmd);
+	scmd->result = 0;
+	set_host_byte(scmd, status);
+	scsi_done(scmd);
+	return true;
+}
+
+/**
+ * scsi_host_complete_all_commands - Terminate all running commands
+ * @shost:	Scsi Host on which commands should be terminated
+ * @status:	Status to be set for the terminated commands
+ *
+ * There is no protection against modification of the number
+ * of outstanding commands. It is the responsibility of the
+ * caller to ensure that concurrent I/O submission and/or
+ * completion is stopped when calling this function.
+ */
+void scsi_host_complete_all_commands(struct Scsi_Host *shost,
+				     enum scsi_host_status status)
+{
+	blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
+				&status);
+}
+EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
+
+struct scsi_host_busy_iter_data {
+	bool (*fn)(struct scsi_cmnd *, void *);
+	void *priv;
+};
+
+static bool __scsi_host_busy_iter_fn(struct request *req, void *priv)
+{
+	struct scsi_host_busy_iter_data *iter_data = priv;
+	struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
+
+	return iter_data->fn(sc, iter_data->priv);
+}
+
+/**
+ * scsi_host_busy_iter - Iterate over all busy commands
+ * @shost:	Pointer to Scsi_Host.
+ * @fn:		Function to call on each busy command
+ * @priv:	Data pointer passed to @fn
+ *
+ * If locking against concurrent command completions is required
+ * ithas to be provided by the caller
+ **/
+void scsi_host_busy_iter(struct Scsi_Host *shost,
+			 bool (*fn)(struct scsi_cmnd *, void *),
+			 void *priv)
+{
+	struct scsi_host_busy_iter_data iter_data = {
+		.fn = fn,
+		.priv = priv,
+	};
+
+	blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
+				&iter_data);
+}
+EXPORT_SYMBOL_GPL(scsi_host_busy_iter);