isci: Termination handling cleanup, added termination timeouts.

[deliverable/linux.git] / drivers / scsi / isci / task.c

/*
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 * The full GNU General Public License is included in this distribution
 * in the file called LICENSE.GPL.
 *
 * BSD LICENSE
 *
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/completion.h>
#include "scic_task_request.h"
#include "scic_remote_device.h"
#include "scic_io_request.h"
#include "scic_sds_remote_device.h"
#include "scic_sds_remote_node_context.h"
#include "isci.h"
#include "request.h"
#include "sata.h"
#include "task.h"


/**
 * isci_task_execute_task() - This function is one of the SAS Domain Template
 *    functions. This function is called by libsas to send a task down to
 *    hardware.
 * @task: This parameter specifies the SAS task to send.
 * @num: This parameter specifies the number of tasks to queue.
 * @gfp_flags: This parameter specifies the context of this call.
 *
 * status, zero indicates success.
 */
int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
{
        struct isci_host *isci_host;
        struct isci_request *request = NULL;
        struct isci_remote_device *device;
        unsigned long flags;
        int ret;
        enum sci_status status;
        enum isci_status device_status;

        dev_dbg(task->dev->port->ha->dev, "%s: num=%d\n", __func__, num);

        if ((task->dev == NULL) || (task->dev->port == NULL)) {

                /* Indicate SAS_TASK_UNDELIVERED, so that the scsi midlayer
                 * removes the target.
                 */
                isci_task_complete_for_upper_layer(
                        task,
                        SAS_TASK_UNDELIVERED,
                        SAS_DEVICE_UNKNOWN,
                        isci_perform_normal_io_completion
                        );
                return 0;  /* The I/O was accepted (and failed). */
        }
        isci_host = isci_host_from_sas_ha(task->dev->port->ha);

        /* Check if we have room for more tasks */
        ret = isci_host_can_queue(isci_host, num);

        if (ret) {
                dev_warn(task->dev->port->ha->dev, "%s: queue full\n", __func__);
                return ret;
        }

        do {
                dev_dbg(task->dev->port->ha->dev,
                        "task = %p, num = %d; dev = %p; cmd = %p\n",
                            task, num, task->dev, task->uldd_task);

                if ((task->dev == NULL) || (task->dev->port == NULL)) {
                        dev_warn(task->dev->port->ha->dev,
                                 "%s: task %p's port or dev == NULL!\n",
                                 __func__, task);

                        /* Indicate SAS_TASK_UNDELIVERED, so that the scsi
                         * midlayer removes the target.
                         */
                        isci_task_complete_for_upper_layer(
                                task,
                                SAS_TASK_UNDELIVERED,
                                SAS_DEVICE_UNKNOWN,
                                isci_perform_normal_io_completion
                                );
                        /* We don't have a valid host reference, so we
                         * can't control the host queueing condition.
                         */
                        goto next_task;
                }

                device = isci_dev_from_domain_dev(task->dev);

                isci_host = isci_host_from_sas_ha(task->dev->port->ha);

                if (device)
                        device_status = device->status;
                else
                        device_status = isci_freed;

                /* From this point onward, any process that needs to guarantee
                 * that there is no kernel I/O being started will have to wait
                 * for the quiesce spinlock.
                 */

                if (device_status != isci_ready_for_io) {

                        /* Forces a retry from scsi mid layer. */
                        dev_warn(task->dev->port->ha->dev,
                                 "%s: task %p: isci_host->status = %d, "
                                 "device = %p; device_status = 0x%x\n\n",
                                 __func__,
                                 task,
                                 isci_host_get_state(isci_host),
                                 device, device_status);

                        if (device_status == isci_ready) {
                                /* Indicate QUEUE_FULL so that the scsi midlayer
                                * retries.
                                */
                                isci_task_complete_for_upper_layer(
                                        task,
                                        SAS_TASK_COMPLETE,
                                        SAS_QUEUE_FULL,
                                        isci_perform_normal_io_completion
                                        );
                        } else {
                                /* Else, the device is going down. */
                                isci_task_complete_for_upper_layer(
                                        task,
                                        SAS_TASK_UNDELIVERED,
                                        SAS_DEVICE_UNKNOWN,
                                        isci_perform_normal_io_completion
                                        );
                        }
                        isci_host_can_dequeue(isci_host, 1);
                } else {
                        /* There is a device and it's ready for I/O. */
                        spin_lock_irqsave(&task->task_state_lock, flags);

                        if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {

                                spin_unlock_irqrestore(&task->task_state_lock,
                                                       flags);

                                isci_task_complete_for_upper_layer(
                                        task,
                                        SAS_TASK_UNDELIVERED,
                                        SAM_STAT_TASK_ABORTED,
                                        isci_perform_normal_io_completion
                                        );

                                /* The I/O was aborted. */

                        } else {
                                task->task_state_flags |= SAS_TASK_AT_INITIATOR;
                                spin_unlock_irqrestore(&task->task_state_lock, flags);

                                /* build and send the request. */
                                status = isci_request_execute(isci_host, task, &request,
                                                              gfp_flags);

                                if (status != SCI_SUCCESS) {

                                        spin_lock_irqsave(&task->task_state_lock, flags);
                                        /* Did not really start this command. */
                                        task->task_state_flags &= ~SAS_TASK_AT_INITIATOR;
                                        spin_unlock_irqrestore(&task->task_state_lock, flags);

                                        /* Indicate QUEUE_FULL so that the scsi
                                        * midlayer retries. if the request
                                        * failed for remote device reasons,
                                        * it gets returned as
                                        * SAS_TASK_UNDELIVERED next time
                                        * through.
                                        */
                                        isci_task_complete_for_upper_layer(
                                                task,
                                                SAS_TASK_COMPLETE,
                                                SAS_QUEUE_FULL,
                                                isci_perform_normal_io_completion
                                                );
                                        isci_host_can_dequeue(isci_host, 1);
                                }
                        }
                }
next_task:
                task = list_entry(task->list.next, struct sas_task, list);
        } while (--num > 0);
        return 0;
}



/**
 * isci_task_request_build() - This function builds the task request object.
 * @isci_host: This parameter specifies the ISCI host object
 * @request: This parameter points to the isci_request object allocated in the
 *    request construct function.
 * @tmf: This parameter is the task management struct to be built
 *
 * SCI_SUCCESS on successfull completion, or specific failure code.
 */
static enum sci_status isci_task_request_build(
        struct isci_host *isci_host,
        struct isci_request **isci_request,
        struct isci_tmf *isci_tmf)
{
        struct scic_sds_remote_device *sci_device;
        enum sci_status status = SCI_FAILURE;
        struct isci_request *request;
        struct isci_remote_device *isci_device;
/*      struct sci_sas_identify_address_frame_protocols dev_protocols; */
        struct smp_discover_response_protocols dev_protocols;


        dev_dbg(&isci_host->pdev->dev,
                "%s: isci_tmf = %p\n", __func__, isci_tmf);

        isci_device = isci_tmf->device;
        sci_device = to_sci_dev(isci_device);

        /* do common allocation and init of request object. */
        status = isci_request_alloc_tmf(
                isci_host,
                isci_tmf,
                &request,
                isci_device,
                GFP_ATOMIC
                );

        if (status != SCI_SUCCESS)
                goto out;

        /* let the core do it's construct. */
        status = scic_task_request_construct(
                isci_host->core_controller,
                sci_device,
                SCI_CONTROLLER_INVALID_IO_TAG,
                request,
                request->sci_request_mem_ptr,
                &request->sci_request_handle
                );

        if (status != SCI_SUCCESS) {
                dev_warn(&isci_host->pdev->dev,
                         "%s: scic_task_request_construct failed - "
                         "status = 0x%x\n",
                         __func__,
                         status);
                goto errout;
        }

        sci_object_set_association(
                request->sci_request_handle,
                request
                );

        scic_remote_device_get_protocols(
                sci_device,
                &dev_protocols
                );

        /* let the core do it's protocol
         * specific construction.
         */
        if (dev_protocols.u.bits.attached_ssp_target) {

                isci_tmf->proto = SAS_PROTOCOL_SSP;
                status = scic_task_request_construct_ssp(
                        request->sci_request_handle
                        );
                if (status != SCI_SUCCESS)
                        goto errout;
        }

        if (dev_protocols.u.bits.attached_stp_target) {

                isci_tmf->proto = SAS_PROTOCOL_SATA;
                status = isci_sata_management_task_request_build(request);

                if (status != SCI_SUCCESS)
                        goto errout;
        }

        goto out;

 errout:

        /* release the dma memory if we fail. */
        isci_request_free(isci_host, request);
        request = NULL;

 out:
        *isci_request = request;
        return status;
}

/**
 * isci_tmf_timeout_cb() - This function is called as a kernel callback when
 *    the timeout period for the TMF has expired.
 *
 *
 */
static void isci_tmf_timeout_cb(void *tmf_request_arg)
{
        struct isci_request *request = (struct isci_request *)tmf_request_arg;
        struct isci_tmf *tmf = isci_request_access_tmf(request);
        enum sci_status status;

        BUG_ON(request->ttype != tmf_task);

        /* This task management request has timed-out.  Terminate the request
         * so that the request eventually completes to the requestor in the
         * request completion callback path.
         */
        /* Note - the timer callback function itself has provided spinlock
         * exclusion from the start and completion paths.  No need to take
         * the request->isci_host->scic_lock here.
         */

        if (tmf->timeout_timer != NULL) {
                /* Call the users callback, if any. */
                if (tmf->cb_state_func != NULL)
                        tmf->cb_state_func(isci_tmf_timed_out, tmf,
                                           tmf->cb_data);

                /* Terminate the TMF transmit request. */
                status = scic_controller_terminate_request(
                        request->isci_host->core_controller,
                        to_sci_dev(request->isci_device),
                        request->sci_request_handle
                        );

                dev_dbg(&request->isci_host->pdev->dev,
                        "%s: tmf_request = %p; tmf = %p; status = %d\n",
                        __func__, request, tmf, status);
        } else
                dev_dbg(&request->isci_host->pdev->dev,
                        "%s: timer already canceled! "
                        "tmf_request = %p; tmf = %p\n",
                        __func__, request, tmf);

        /* No need to unlock since the caller to this callback is doing it for
         * us.
         * request->isci_host->scic_lock
         */
}

/**
 * isci_task_execute_tmf() - This function builds and sends a task request,
 *    then waits for the completion.
 * @isci_host: This parameter specifies the ISCI host object
 * @tmf: This parameter is the pointer to the task management structure for
 *    this request.
 * @timeout_ms: This parameter specifies the timeout period for the task
 *    management request.
 *
 * TMF_RESP_FUNC_COMPLETE on successful completion of the TMF (this includes
 * error conditions reported in the IU status), or TMF_RESP_FUNC_FAILED.
 */
int isci_task_execute_tmf(
        struct isci_host *isci_host,
        struct isci_tmf *tmf,
        unsigned long timeout_ms)
{
        DECLARE_COMPLETION_ONSTACK(completion);
        enum sci_status status = SCI_FAILURE;
        struct scic_sds_remote_device *sci_device;
        struct isci_remote_device *isci_device = tmf->device;
        struct isci_request *request;
        int ret = TMF_RESP_FUNC_FAILED;
        unsigned long flags;

        /* sanity check, return TMF_RESP_FUNC_FAILED
         * if the device is not there and ready.
         */
        if (!isci_device || isci_device->status != isci_ready_for_io) {
                dev_dbg(&isci_host->pdev->dev,
                        "%s: isci_device = %p not ready (%d)\n",
                        __func__,
                        isci_device, isci_device->status);
                return TMF_RESP_FUNC_FAILED;
        } else
                dev_dbg(&isci_host->pdev->dev,
                        "%s: isci_device = %p\n",
                        __func__, isci_device);

        sci_device = to_sci_dev(isci_device);

        /* Assign the pointer to the TMF's completion kernel wait structure. */
        tmf->complete = &completion;

        isci_task_request_build(
                isci_host,
                &request,
                tmf
                );

        if (!request) {
                dev_warn(&isci_host->pdev->dev,
                        "%s: isci_task_request_build failed\n",
                        __func__);
                return TMF_RESP_FUNC_FAILED;
        }

        /* Allocate the TMF timeout timer. */
        spin_lock_irqsave(&isci_host->scic_lock, flags);
        tmf->timeout_timer = isci_timer_create(isci_host, request, isci_tmf_timeout_cb);

        /* Start the timer. */
        if (tmf->timeout_timer)
                isci_timer_start(tmf->timeout_timer, timeout_ms);
        else
                dev_warn(&isci_host->pdev->dev,
                         "%s: isci_timer_create failed!!!!\n",
                         __func__);

        /* start the TMF io. */
        status = scic_controller_start_task(
                isci_host->core_controller,
                sci_device,
                request->sci_request_handle,
                SCI_CONTROLLER_INVALID_IO_TAG
                );

        if (status != SCI_SUCCESS) {
                dev_warn(&isci_host->pdev->dev,
                         "%s: start_io failed - status = 0x%x, request = %p\n",
                         __func__,
                         status,
                         request);
                goto cleanup_request;
        }

        /* Call the users callback, if any. */
        if (tmf->cb_state_func != NULL)
                tmf->cb_state_func(isci_tmf_started, tmf, tmf->cb_data);

        /* Change the state of the TMF-bearing request to "started". */
        isci_request_change_state(request, started);

        /* add the request to the remote device request list. */
        list_add(&request->dev_node, &isci_device->reqs_in_process);

        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        /* Wait for the TMF to complete, or a timeout. */
        wait_for_completion(&completion);

        isci_print_tmf(tmf);

        if (tmf->status == SCI_SUCCESS)
                ret =  TMF_RESP_FUNC_COMPLETE;
        else if (tmf->status == SCI_FAILURE_IO_RESPONSE_VALID) {
                dev_dbg(&isci_host->pdev->dev,
                        "%s: tmf.status == "
                        "SCI_FAILURE_IO_RESPONSE_VALID\n",
                        __func__);
                ret =  TMF_RESP_FUNC_COMPLETE;
        }
        /* Else - leave the default "failed" status alone. */

        dev_dbg(&isci_host->pdev->dev,
                "%s: completed request = %p\n",
                __func__,
                request);

        if (request->io_request_completion != NULL) {

                /* The fact that this is non-NULL for a TMF request
                 * means there is a thread waiting for this TMF to
                 * finish.
                 */
                complete(request->io_request_completion);
        }

        spin_lock_irqsave(&isci_host->scic_lock, flags);

 cleanup_request:

        /* Clean up the timer if needed. */
        if (tmf->timeout_timer) {
                isci_del_timer(isci_host, tmf->timeout_timer);
                tmf->timeout_timer = NULL;
        }

        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        isci_request_free(isci_host, request);

        return ret;
}

void isci_task_build_tmf(
        struct isci_tmf *tmf,
        struct isci_remote_device *isci_device,
        enum isci_tmf_function_codes code,
        void (*tmf_sent_cb)(enum isci_tmf_cb_state,
                            struct isci_tmf *,
                            void *),
        struct isci_request *old_request)
{
        dev_dbg(&isci_device->isci_port->isci_host->pdev->dev,
                "%s: isci_device = %p\n", __func__, isci_device);

        memset(tmf, 0, sizeof(*tmf));

        tmf->device        = isci_device;
        tmf->tmf_code      = code;
        tmf->timeout_timer = NULL;
        tmf->cb_state_func = tmf_sent_cb;
        tmf->cb_data       = old_request;
        tmf->io_tag        = old_request->io_tag;

}

static struct isci_request *isci_task_get_request_from_task(
        struct sas_task *task,
        struct isci_host **isci_host,
        struct isci_remote_device **isci_device)
{

        struct isci_request *request = NULL;
        unsigned long flags;

        spin_lock_irqsave(&task->task_state_lock, flags);

        request = task->lldd_task;

        /* If task is already done, the request isn't valid */
        if (!(task->task_state_flags & SAS_TASK_STATE_DONE) &&
            (task->task_state_flags & SAS_TASK_AT_INITIATOR) &&
            (request != NULL)) {

                if (isci_host != NULL)
                        *isci_host = request->isci_host;

                if (isci_device != NULL)
                        *isci_device = request->isci_device;
        }

        spin_unlock_irqrestore(&task->task_state_lock, flags);

        return request;
}

/**
 * isci_task_validate_request_to_abort() - This function checks the given I/O
 *    against the "started" state.  If the request is still "started", it's
 *    state is changed to aborted. NOTE: isci_host->scic_lock MUST BE HELD
 *    BEFORE CALLING THIS FUNCTION.
 * @isci_request: This parameter specifies the request object to control.
 * @isci_host: This parameter specifies the ISCI host object
 * @isci_device: This is the device to which the request is pending.
 * @aborted_io_completion: This is a completion structure that will be added to
 *    the request in case it is changed to aborting; this completion is
 *    triggered when the request is fully completed.
 *
 * Either "started" on successful change of the task status to "aborted", or
 * "unallocated" if the task cannot be controlled.
 */
static enum isci_request_status isci_task_validate_request_to_abort(
        struct isci_request *isci_request,
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        struct completion *aborted_io_completion)
{
        enum isci_request_status old_state = unallocated;

        /* Only abort the task if it's in the
         *  device's request_in_process list
         */
        if (isci_request && !list_empty(&isci_request->dev_node)) {
                old_state = isci_request_change_started_to_aborted(
                        isci_request, aborted_io_completion);

        }

        return old_state;
}

static void isci_request_cleanup_completed_loiterer(
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        struct isci_request *isci_request)
{
        struct sas_task     *task;
        unsigned long       flags;

        task = (isci_request->ttype == io_task)
                ? isci_request_access_task(isci_request)
                : NULL;

        dev_dbg(&isci_host->pdev->dev,
                "%s: isci_device=%p, request=%p, task=%p\n",
                __func__, isci_device, isci_request, task);

        spin_lock_irqsave(&isci_host->scic_lock, flags);
        list_del_init(&isci_request->dev_node);
        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        if (task != NULL) {

                spin_lock_irqsave(&task->task_state_lock, flags);
                task->lldd_task = NULL;

                isci_set_task_doneflags(task);

                /* If this task is not in the abort path, call task_done. */
                if (!(task->task_state_flags & SAS_TASK_STATE_ABORTED)) {

                        spin_unlock_irqrestore(&task->task_state_lock, flags);
                        task->task_done(task);
                } else
                        spin_unlock_irqrestore(&task->task_state_lock, flags);
        }
        isci_request_free(isci_host, isci_request);
}

/**
* @isci_termination_timed_out(): this function will deal with a request for
* which the wait for termination has timed-out.
*
* @isci_host    This SCU.
* @isci_request The I/O request being terminated.
*/
static void
isci_termination_timed_out(
        struct isci_host    * host,
        struct isci_request * request
        )
{
        unsigned long state_flags;

        dev_warn(&host->pdev->dev,
                "%s: host = %p; request = %p\n",
                __func__, host, request);

        /* At this point, the request to terminate
        * has timed out. The best we can do is to
        * have the request die a silent death
        * if it ever completes.
        */
        spin_lock_irqsave(&request->state_lock, state_flags);

        if (request->status == started) {

                /* Set the request state to "dead",
                * and clear the task pointer so that an actual
                * completion event callback doesn't do
                * anything.
                */
                request->status = dead;

                /* Clear the timeout completion event pointer.*/
                request->io_request_completion = NULL;

                if (request->ttype == io_task) {

                        /* Break links with the sas_task. */
                        if (request->ttype_ptr.io_task_ptr != NULL) {

                                request->ttype_ptr.io_task_ptr->lldd_task = NULL;
                                request->ttype_ptr.io_task_ptr            = NULL;
                        }
                }
        }
        spin_unlock_irqrestore(&request->state_lock, state_flags);
}


/**
 * isci_terminate_request_core() - This function will terminate the given
 *    request, and wait for it to complete.  This function must only be called
 *    from a thread that can wait.  Note that the request is terminated and
 *    completed (back to the host, if started there).
 * @isci_host: This SCU.
 * @isci_device: The target.
 * @isci_request: The I/O request to be terminated.
 *
 *
 */
static void isci_terminate_request_core(
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        struct isci_request *isci_request)
{
        enum sci_status status      = SCI_SUCCESS;
        bool was_terminated         = false;
        bool needs_cleanup_handling = false;
        enum isci_request_status request_status;
        unsigned long flags;
        unsigned long timeout_remaining;


        dev_dbg(&isci_host->pdev->dev,
                "%s: device = %p; request = %p\n",
                __func__, isci_device, isci_request);

        spin_lock_irqsave(&isci_host->scic_lock, flags);

        /* Note that we are not going to control
        * the target to abort the request.
        */
        isci_request->complete_in_target = true;

        /* Make sure the request wasn't just sitting around signalling
         * device condition (if the request handle is NULL, then the
         * request completed but needed additional handling here).
         */
        if (isci_request->sci_request_handle != NULL) {
                was_terminated = true;
                needs_cleanup_handling = true;
                status = scic_controller_terminate_request(
                        isci_host->core_controller,
                        to_sci_dev(isci_device),
                        isci_request->sci_request_handle
                        );
        }
        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        /*
         * The only time the request to terminate will
         * fail is when the io request is completed and
         * being aborted.
         */
        if (status != SCI_SUCCESS) {
                dev_err(&isci_host->pdev->dev,
                        "%s: scic_controller_terminate_request"
                        " returned = 0x%x\n",
                        __func__,
                        status);
                /* Clear the completion pointer from the request. */
                isci_request->io_request_completion = NULL;

        } else {
                if (was_terminated) {
                        dev_dbg(&isci_host->pdev->dev,
                                "%s: before completion wait (%p)\n",
                                __func__,
                                isci_request->io_request_completion);

                        /* Wait here for the request to complete. */
                        #define TERMINATION_TIMEOUT_MSEC 50
                        timeout_remaining
                                = wait_for_completion_timeout(
                                   isci_request->io_request_completion,
                                   msecs_to_jiffies(TERMINATION_TIMEOUT_MSEC));

                        if (!timeout_remaining) {

                                isci_termination_timed_out(isci_host,
                                                           isci_request);

                                dev_err(&isci_host->pdev->dev,
                                        "%s: *** Timeout waiting for "
                                        "termination(%p/%p)\n",
                                        __func__,
                                        isci_request->io_request_completion,
                                        isci_request);

                        } else
                                dev_dbg(&isci_host->pdev->dev,
                                        "%s: after completion wait (%p)\n",
                                        __func__,
                                        isci_request->io_request_completion);
                }
                /* Clear the completion pointer from the request. */
                isci_request->io_request_completion = NULL;

                /* Peek at the status of the request.  This will tell
                * us if there was special handling on the request such that it
                * needs to be detached and freed here.
                */
                spin_lock_irqsave(&isci_request->state_lock, flags);
                request_status = isci_request_get_state(isci_request);

                if ((isci_request->ttype == io_task) /* TMFs are in their own thread */
                    && ((request_status == aborted)
                        || (request_status == aborting)
                        || (request_status == terminating)
                        || (request_status == completed)
                        || (request_status == dead)
                        )
                    ) {

                        /* The completion routine won't free a request in
                        * the aborted/aborting/etc. states, so we do
                        * it here.
                        */
                        needs_cleanup_handling = true;
                }
                spin_unlock_irqrestore(&isci_request->state_lock, flags);

                if (needs_cleanup_handling)
                        isci_request_cleanup_completed_loiterer(
                                isci_host, isci_device, isci_request
                                );
        }
}

static void isci_terminate_request(
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        struct isci_request *isci_request,
        enum isci_request_status new_request_state)
{
        enum isci_request_status old_state;
        DECLARE_COMPLETION_ONSTACK(request_completion);

        /* Change state to "new_request_state" if it is currently "started" */
        old_state = isci_request_change_started_to_newstate(
                isci_request,
                &request_completion,
                new_request_state
                );

        if ((old_state == started) || (old_state == completed)) {

                /* If the old_state is started:
                 * This request was not already being aborted. If it had been,
                 * then the aborting I/O (ie. the TMF request) would not be in
                 * the aborting state, and thus would be terminated here.  Note
                 * that since the TMF completion's call to the kernel function
                 * "complete()" does not happen until the pending I/O request
                 * terminate fully completes, we do not have to implement a
                 * special wait here for already aborting requests - the
                 * termination of the TMF request will force the request
                 * to finish it's already started terminate.
                 *
                 * If old_state == completed:
                 * This request completed from the SCU hardware perspective
                 * and now just needs cleaning up in terms of freeing the
                 * request and potentially calling up to libsas.
                 */
                isci_terminate_request_core(isci_host, isci_device,
                                            isci_request);
        }
}

/**
 * isci_terminate_pending_requests() - This function will change the all of the
 *    requests on the given device's state to "aborting", will terminate the
 *    requests, and wait for them to complete.  This function must only be
 *    called from a thread that can wait.  Note that the requests are all
 *    terminated and completed (back to the host, if started there).
 * @isci_host: This parameter specifies SCU.
 * @isci_device: This parameter specifies the target.
 *
 *
 */
void isci_terminate_pending_requests(
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        enum isci_request_status new_request_state)
{
        struct isci_request *request;
        struct isci_request *next_request;
        unsigned long       flags;
        struct list_head    aborted_request_list;

        INIT_LIST_HEAD(&aborted_request_list);

        dev_dbg(&isci_host->pdev->dev,
                "%s: isci_device = %p (new request state = %d)\n",
                __func__, isci_device, new_request_state);

        spin_lock_irqsave(&isci_host->scic_lock, flags);

        /* Move all of the pending requests off of the device list. */
        list_splice_init(&isci_device->reqs_in_process,
                         &aborted_request_list);

        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        /* Iterate through the now-local list. */
        list_for_each_entry_safe(request, next_request,
                                 &aborted_request_list, dev_node) {

                dev_warn(&isci_host->pdev->dev,
                        "%s: isci_device=%p request=%p; task=%p\n",
                        __func__,
                        isci_device, request,
                        ((request->ttype == io_task)
                                ? isci_request_access_task(request)
                                : NULL));

                /* Mark all still pending I/O with the selected next
                * state, terminate and free it.
                */
                isci_terminate_request(isci_host, isci_device,
                                       request, new_request_state
                                       );
        }
}

/**
 * isci_task_send_lu_reset_sas() - This function is called by of the SAS Domain
 *    Template functions.
 * @lun: This parameter specifies the lun to be reset.
 *
 * status, zero indicates success.
 */
static int isci_task_send_lu_reset_sas(
        struct isci_host *isci_host,
        struct isci_remote_device *isci_device,
        u8 *lun)
{
        struct isci_tmf tmf;
        int ret = TMF_RESP_FUNC_FAILED;

        dev_dbg(&isci_host->pdev->dev,
                "%s: isci_host = %p, isci_device = %p\n",
                __func__, isci_host, isci_device);
        /* Send the LUN reset to the target.  By the time the call returns,
         * the TMF has fully exected in the target (in which case the return
         * value is "TMF_RESP_FUNC_COMPLETE", or the request timed-out (or
         * was otherwise unable to be executed ("TMF_RESP_FUNC_FAILED").
         */
        isci_task_build_tmf(&tmf, isci_device, isci_tmf_ssp_lun_reset, NULL,
                            NULL);

        #define ISCI_LU_RESET_TIMEOUT_MS 2000 /* 2 second timeout. */
        ret = isci_task_execute_tmf(isci_host, &tmf, ISCI_LU_RESET_TIMEOUT_MS);

        if (ret == TMF_RESP_FUNC_COMPLETE)
                dev_dbg(&isci_host->pdev->dev,
                        "%s: %p: TMF_LU_RESET passed\n",
                        __func__, isci_device);
        else
                dev_dbg(&isci_host->pdev->dev,
                        "%s: %p: TMF_LU_RESET failed (%x)\n",
                        __func__, isci_device, ret);

        return ret;
}

/**
 * isci_task_lu_reset() - This function is one of the SAS Domain Template
 *    functions. This is one of the Task Management functoins called by libsas,
 *    to reset the given lun. Note the assumption that while this call is
 *    executing, no I/O will be sent by the host to the device.
 * @lun: This parameter specifies the lun to be reset.
 *
 * status, zero indicates success.
 */
int isci_task_lu_reset(
        struct domain_device *domain_device,
        u8 *lun)
{
        struct isci_host *isci_host = NULL;
        struct isci_remote_device *isci_device = NULL;
        int ret;
        bool device_stopping = false;

        if (domain_device == NULL) {
                pr_warn("%s: domain_device == NULL\n", __func__);
                return TMF_RESP_FUNC_FAILED;
        }

        isci_device = isci_dev_from_domain_dev(domain_device);

        if (domain_device->port != NULL)
                isci_host = isci_host_from_sas_ha(domain_device->port->ha);

        pr_debug("%s: domain_device=%p, isci_host=%p; isci_device=%p\n",
                 __func__, domain_device, isci_host, isci_device);

        if (isci_device != NULL)
                device_stopping = (isci_device->status == isci_stopping)
                                  || (isci_device->status == isci_stopped);

        /* If there is a device reset pending on any request in the
         * device's list, fail this LUN reset request in order to
         * escalate to the device reset.
         */
        if ((isci_device == NULL) ||
            (isci_host == NULL) ||
            ((isci_host != NULL) &&
             (isci_device != NULL) &&
             (device_stopping ||
              (isci_device_is_reset_pending(isci_host, isci_device))))) {
                dev_warn(&isci_host->pdev->dev,
                         "%s: No dev (%p), no host (%p), or "
                         "RESET PENDING: domain_device=%p\n",
                         __func__, isci_device, isci_host, domain_device);
                return TMF_RESP_FUNC_FAILED;
        }

        /* Send the task management part of the reset. */
        if (sas_protocol_ata(domain_device->tproto)) {
                ret = isci_task_send_lu_reset_sata(
                        isci_host, isci_device, lun
                        );
        } else
                ret = isci_task_send_lu_reset_sas(isci_host, isci_device, lun);

        /* If the LUN reset worked, all the I/O can now be terminated. */
        if (ret == TMF_RESP_FUNC_COMPLETE)
                /* Terminate all I/O now. */
                isci_terminate_pending_requests(isci_host,
                                                isci_device,
                                                terminating);

        return ret;
}


/*       int (*lldd_clear_nexus_port)(struct asd_sas_port *); */
int isci_task_clear_nexus_port(struct asd_sas_port *port)
{
        return TMF_RESP_FUNC_FAILED;
}



int isci_task_clear_nexus_ha(struct sas_ha_struct *ha)
{
        return TMF_RESP_FUNC_FAILED;
}

int isci_task_I_T_nexus_reset(struct domain_device *dev)
{
        return TMF_RESP_FUNC_FAILED;
}


/* Task Management Functions. Must be called from process context.       */

/**
 * isci_abort_task_process_cb() - This is a helper function for the abort task
 *    TMF command.  It manages the request state with respect to the successful
 *    transmission / completion of the abort task request.
 * @cb_state: This parameter specifies when this function was called - after
 *    the TMF request has been started and after it has timed-out.
 * @tmf: This parameter specifies the TMF in progress.
 *
 *
 */
static void isci_abort_task_process_cb(
        enum isci_tmf_cb_state cb_state,
        struct isci_tmf *tmf,
        void *cb_data)
{
        struct isci_request *old_request;

        old_request = (struct isci_request *)cb_data;

        dev_dbg(&old_request->isci_host->pdev->dev,
                "%s: tmf=%p, old_request=%p\n",
                __func__, tmf, old_request);

        switch (cb_state) {

        case isci_tmf_started:
                /* The TMF has been started.  Nothing to do here, since the
                 * request state was already set to "aborted" by the abort
                 * task function.
                 */
                BUG_ON(old_request->status != aborted);
                break;

        case isci_tmf_timed_out:

                /* Set the task's state to "aborting", since the abort task
                 * function thread set it to "aborted" (above) in anticipation
                 * of the task management request working correctly.  Since the
                 * timeout has now fired, the TMF request failed.  We set the
                 * state such that the request completion will indicate the
                 * device is no longer present.
                 */
                isci_request_change_state(old_request, aborting);
                break;

        default:
                dev_err(&old_request->isci_host->pdev->dev,
                        "%s: Bad cb_state (%d): tmf=%p, old_request=%p\n",
                        __func__, cb_state, tmf, old_request);
                break;
        }
}

/**
 * isci_task_abort_task() - This function is one of the SAS Domain Template
 *    functions. This function is called by libsas to abort a specified task.
 * @task: This parameter specifies the SAS task to abort.
 *
 * status, zero indicates success.
 */
int isci_task_abort_task(struct sas_task *task)
{
        DECLARE_COMPLETION_ONSTACK(aborted_io_completion);
        struct isci_request       *old_request = NULL;
        enum isci_request_status  old_state;
        struct isci_remote_device *isci_device = NULL;
        struct isci_host          *isci_host = NULL;
        struct isci_tmf           tmf;
        int                       ret = TMF_RESP_FUNC_FAILED;
        unsigned long             flags;
        bool                      any_dev_reset = false;
        bool                      device_stopping;

        /* Get the isci_request reference from the task.  Note that
         * this check does not depend on the pending request list
         * in the device, because tasks driving resets may land here
         * after completion in the core.
         */
        old_request = isci_task_get_request_from_task(task, &isci_host,
                                                      &isci_device);

        dev_dbg(&isci_host->pdev->dev,
                "%s: task = %p\n", __func__, task);

        /* Check if the device has been / is currently being removed.
         * If so, no task management will be done, and the I/O will
         * be terminated.
         */
        device_stopping = (isci_device->status == isci_stopping)
                          || (isci_device->status == isci_stopped);

        /* This version of the driver will fail abort requests for
         * SATA/STP.  Failing the abort request this way will cause the
         * SCSI error handler thread to escalate to LUN reset
         */
        if (sas_protocol_ata(task->task_proto) && !device_stopping) {
                dev_warn(&isci_host->pdev->dev,
                            " task %p is for a STP/SATA device;"
                            " returning TMF_RESP_FUNC_FAILED\n"
                            " to cause a LUN reset...\n", task);
                return TMF_RESP_FUNC_FAILED;
        }

        dev_dbg(&isci_host->pdev->dev,
                "%s: old_request == %p\n", __func__, old_request);

        if (!device_stopping)
                any_dev_reset = isci_device_is_reset_pending(isci_host,isci_device);

        spin_lock_irqsave(&task->task_state_lock, flags);

        /* Don't do resets to stopping devices. */
        if (device_stopping) {

                task->task_state_flags &= ~SAS_TASK_NEED_DEV_RESET;
                any_dev_reset = false;

        } else  /* See if there is a pending device reset for this device. */
                any_dev_reset = any_dev_reset
                        || (task->task_state_flags & SAS_TASK_NEED_DEV_RESET);

        /* If the extraction of the request reference from the task
         * failed, then the request has been completed (or if there is a
         * pending reset then this abort request function must be failed
         * in order to escalate to the target reset).
         */
        if ((old_request == NULL) || any_dev_reset) {

                /* If the device reset task flag is set, fail the task
                 * management request.  Otherwise, the original request
                 * has completed.
                 */
                if (any_dev_reset) {

                        /* Turn off the task's DONE to make sure this
                         * task is escalated to a target reset.
                         */
                        task->task_state_flags &= ~SAS_TASK_STATE_DONE;

                        /* Make the reset happen as soon as possible. */
                        task->task_state_flags |= SAS_TASK_NEED_DEV_RESET;

                        spin_unlock_irqrestore(&task->task_state_lock, flags);

                        /* Fail the task management request in order to
                         * escalate to the target reset.
                         */
                        ret = TMF_RESP_FUNC_FAILED;

                        dev_dbg(&isci_host->pdev->dev,
                                "%s: Failing task abort in order to "
                                "escalate to target reset because\n"
                                "SAS_TASK_NEED_DEV_RESET is set for "
                                "task %p on dev %p\n",
                                __func__, task, isci_device);


                } else {
                        /* The request has already completed and there
                         * is nothing to do here other than to set the task
                         * done bit, and indicate that the task abort function
                         * was sucessful.
                         */
                        isci_set_task_doneflags(task);

                        spin_unlock_irqrestore(&task->task_state_lock, flags);

                        ret = TMF_RESP_FUNC_COMPLETE;

                        dev_dbg(&isci_host->pdev->dev,
                                "%s: abort task not needed for %p\n",
                                __func__, task);
                }

                return ret;
        }
        else
                spin_unlock_irqrestore(&task->task_state_lock, flags);

        spin_lock_irqsave(&isci_host->scic_lock, flags);

        /* Check the request status and change to "aborting" if currently
         * "starting"; if true then set the I/O kernel completion
         * struct that will be triggered when the request completes.
         */
        old_state = isci_task_validate_request_to_abort(
                                old_request, isci_host, isci_device,
                                &aborted_io_completion);
        if ((old_state != started) && (old_state != completed)) {

                spin_unlock_irqrestore(&isci_host->scic_lock, flags);

                /* The request was already being handled by someone else (because
                * they got to set the state away from started).
                */
                dev_dbg(&isci_host->pdev->dev,
                        "%s:  device = %p; old_request %p already being aborted\n",
                        __func__,
                        isci_device, old_request);

                return TMF_RESP_FUNC_COMPLETE;
        }
        if ((task->task_proto == SAS_PROTOCOL_SMP)
            || device_stopping
            || old_request->complete_in_target
            ) {

                spin_unlock_irqrestore(&isci_host->scic_lock, flags);

                dev_dbg(&isci_host->pdev->dev,
                        "%s: SMP request (%d)"
                        " or device is stopping (%d)"
                        " or complete_in_target (%d), thus no TMF\n",
                        __func__, (task->task_proto == SAS_PROTOCOL_SMP),
                        device_stopping, old_request->complete_in_target);

                /* Set the state on the task. */
                isci_task_all_done(task);

                ret = TMF_RESP_FUNC_COMPLETE;

                /* Stopping and SMP devices are not sent a TMF, and are not
                 * reset, but the outstanding I/O request is terminated below.
                 */
        } else {
                /* Fill in the tmf stucture */
                isci_task_build_tmf(&tmf, isci_device, isci_tmf_ssp_task_abort,
                                    isci_abort_task_process_cb, old_request);

                spin_unlock_irqrestore(&isci_host->scic_lock, flags);

                #define ISCI_ABORT_TASK_TIMEOUT_MS 500 /* half second timeout. */
                ret = isci_task_execute_tmf(isci_host, &tmf,
                                            ISCI_ABORT_TASK_TIMEOUT_MS);

                if (ret != TMF_RESP_FUNC_COMPLETE)
                        dev_err(&isci_host->pdev->dev,
                                "%s: isci_task_send_tmf failed\n",
                                __func__);
        }
        if (ret == TMF_RESP_FUNC_COMPLETE) {
                old_request->complete_in_target = true;

                /* Clean up the request on our side, and wait for the aborted I/O to
                * complete.
                */
                isci_terminate_request_core(isci_host, isci_device, old_request);
        }

        /* Make sure we do not leave a reference to aborted_io_completion */
        old_request->io_request_completion = NULL;
        return ret;
}

/**
 * isci_task_abort_task_set() - This function is one of the SAS Domain Template
 *    functions. This is one of the Task Management functoins called by libsas,
 *    to abort all task for the given lun.
 * @d_device: This parameter specifies the domain device associated with this
 *    request.
 * @lun: This parameter specifies the lun associated with this request.
 *
 * status, zero indicates success.
 */
int isci_task_abort_task_set(
        struct domain_device *d_device,
        u8 *lun)
{
        return TMF_RESP_FUNC_FAILED;
}


/**
 * isci_task_clear_aca() - This function is one of the SAS Domain Template
 *    functions. This is one of the Task Management functoins called by libsas.
 * @d_device: This parameter specifies the domain device associated with this
 *    request.
 * @lun: This parameter specifies the lun        associated with this request.
 *
 * status, zero indicates success.
 */
int isci_task_clear_aca(
        struct domain_device *d_device,
        u8 *lun)
{
        return TMF_RESP_FUNC_FAILED;
}



/**
 * isci_task_clear_task_set() - This function is one of the SAS Domain Template
 *    functions. This is one of the Task Management functoins called by libsas.
 * @d_device: This parameter specifies the domain device associated with this
 *    request.
 * @lun: This parameter specifies the lun        associated with this request.
 *
 * status, zero indicates success.
 */
int isci_task_clear_task_set(
        struct domain_device *d_device,
        u8 *lun)
{
        return TMF_RESP_FUNC_FAILED;
}


/**
 * isci_task_query_task() - This function is implemented to cause libsas to
 *    correctly escalate the failed abort to a LUN or target reset (this is
 *    because sas_scsi_find_task libsas function does not correctly interpret
 *    all return codes from the abort task call).  When TMF_RESP_FUNC_SUCC is
 *    returned, libsas turns this into a LUN reset; when FUNC_FAILED is
 *    returned, libsas will turn this into a target reset
 * @task: This parameter specifies the sas task being queried.
 * @lun: This parameter specifies the lun associated with this request.
 *
 * status, zero indicates success.
 */
int isci_task_query_task(
        struct sas_task *task)
{
        /* See if there is a pending device reset for this device. */
        if (task->task_state_flags & SAS_TASK_NEED_DEV_RESET)
                return TMF_RESP_FUNC_FAILED;
        else
                return TMF_RESP_FUNC_SUCC;
}

/**
 * isci_task_request_complete() - This function is called by the sci core when
 *    an task request completes.
 * @isci_host: This parameter specifies the ISCI host object
 * @request: This parameter is the completed isci_request object.
 * @completion_status: This parameter specifies the completion status from the
 *    sci core.
 *
 * none.
 */
void isci_task_request_complete(
        struct isci_host *isci_host,
        struct isci_request *request,
        enum sci_task_status completion_status)
{
        struct isci_remote_device *isci_device = request->isci_device;
        enum isci_request_status old_state;
        struct isci_tmf *tmf = isci_request_access_tmf(request);
        struct completion *tmf_complete;

        dev_dbg(&isci_host->pdev->dev,
                "%s: request = %p, status=%d\n",
                __func__, request, completion_status);

        old_state = isci_request_change_state(request, completed);

        tmf->status = completion_status;
        request->complete_in_target = true;

        if (SAS_PROTOCOL_SSP == tmf->proto) {

                memcpy(&tmf->resp.resp_iu,
                       scic_io_request_get_response_iu_address(
                               request->sci_request_handle
                               ),
                       sizeof(struct sci_ssp_response_iu));

        } else if (SAS_PROTOCOL_SATA == tmf->proto) {

                memcpy(&tmf->resp.d2h_fis,
                       scic_stp_io_request_get_d2h_reg_address(
                               request->sci_request_handle
                               ),
                       sizeof(struct sata_fis_reg_d2h)
                       );
        }

        /* Manage the timer if it is still running. */
        if (tmf->timeout_timer) {
                isci_del_timer(isci_host, tmf->timeout_timer);
                tmf->timeout_timer = NULL;
        }

        /* PRINT_TMF( ((struct isci_tmf *)request->task)); */
        tmf_complete = tmf->complete;

        scic_controller_complete_task(
                isci_host->core_controller,
                to_sci_dev(isci_device),
                request->sci_request_handle
                );
        /* NULL the request handle to make sure it cannot be terminated
         *  or completed again.
         */
        request->sci_request_handle = NULL;

        isci_request_change_state(request, unallocated);
        list_del_init(&request->dev_node);

        /* The task management part completes last. */
        complete(tmf_complete);
}


/**
 * isci_task_ssp_request_get_lun() - This function is called by the sci core to
 *    retrieve the lun for a given task request.
 * @request: This parameter is the isci_request object.
 *
 * lun for specified task request.
 */
u32 isci_task_ssp_request_get_lun(struct isci_request *request)
{
        struct isci_tmf *isci_tmf = isci_request_access_tmf(request);

        dev_dbg(&request->isci_host->pdev->dev,
                "%s: lun = %d\n", __func__, isci_tmf->lun[0]);
/* @todo: build lun from array of bytes to 32 bit */
        return isci_tmf->lun[0];
}

/**
 * isci_task_ssp_request_get_function() - This function is called by the sci
 *    core to retrieve the function for a given task request.
 * @request: This parameter is the isci_request object.
 *
 * function code for specified task request.
 */
u8 isci_task_ssp_request_get_function(struct isci_request *request)
{
        struct isci_tmf *isci_tmf = isci_request_access_tmf(request);

        dev_dbg(&request->isci_host->pdev->dev,
                "%s: func = %d\n", __func__, isci_tmf->tmf_code);

        return isci_tmf->tmf_code;
}

/**
 * isci_task_ssp_request_get_io_tag_to_manage() - This function is called by
 *    the sci core to retrieve the io tag for a given task request.
 * @request: This parameter is the isci_request object.
 *
 * io tag for specified task request.
 */
u16 isci_task_ssp_request_get_io_tag_to_manage(struct isci_request *request)
{
        u16 io_tag = SCI_CONTROLLER_INVALID_IO_TAG;

        if (tmf_task == request->ttype) {
                struct isci_tmf *tmf = isci_request_access_tmf(request);
                io_tag = tmf->io_tag;
        }

        dev_dbg(&request->isci_host->pdev->dev,
                "%s: request = %p, io_tag = %d\n",
                __func__, request, io_tag);

        return io_tag;
}

/**
 * isci_task_ssp_request_get_response_data_address() - This function is called
 *    by the sci core to retrieve the response data address for a given task
 *    request.
 * @request: This parameter is the isci_request object.
 *
 * response data address for specified task request.
 */
void *isci_task_ssp_request_get_response_data_address(
        struct isci_request *request)
{
        struct isci_tmf *isci_tmf = isci_request_access_tmf(request);

        return &isci_tmf->resp.resp_iu;
}

/**
 * isci_task_ssp_request_get_response_data_length() - This function is called
 *    by the sci core to retrieve the response data length for a given task
 *    request.
 * @request: This parameter is the isci_request object.
 *
 * response data length for specified task request.
 */
u32 isci_task_ssp_request_get_response_data_length(
        struct isci_request *request)
{
        struct isci_tmf *isci_tmf = isci_request_access_tmf(request);

        return sizeof(isci_tmf->resp.resp_iu);
}

/**
 * isci_bus_reset_handler() - This function performs a target reset of the
 *    device referenced by "cmd'.  This function is exported through the
 *    "struct scsi_host_template" structure such that it is called when an I/O
 *    recovery process has escalated to a target reset. Note that this function
 *    is called from the scsi error handler event thread, so may block on calls.
 * @scsi_cmd: This parameter specifies the target to be reset.
 *
 * SUCCESS if the reset process was successful, else FAILED.
 */
int isci_bus_reset_handler(struct scsi_cmnd *cmd)
{
        unsigned long flags = 0;
        struct isci_host *isci_host = NULL;
        enum sci_status status;
        int base_status;
        struct isci_remote_device *isci_dev
                = isci_dev_from_domain_dev(
                sdev_to_domain_dev(cmd->device));

        dev_dbg(&cmd->device->sdev_gendev,
                "%s: cmd %p, isci_dev %p\n",
                __func__, cmd, isci_dev);

        if (!isci_dev) {
                dev_warn(&cmd->device->sdev_gendev,
                         "%s: isci_dev is GONE!\n",
                         __func__);

                return TMF_RESP_FUNC_COMPLETE; /* Nothing to reset. */
        }

        if (isci_dev->isci_port != NULL)
                isci_host = isci_dev->isci_port->isci_host;

        if (isci_host != NULL)
                spin_lock_irqsave(&isci_host->scic_lock, flags);

        status = scic_remote_device_reset(to_sci_dev(isci_dev));
        if (status != SCI_SUCCESS) {

                if (isci_host != NULL)
                        spin_unlock_irqrestore(&isci_host->scic_lock, flags);

                scmd_printk(KERN_WARNING, cmd,
                            "%s: scic_remote_device_reset(%p) returned %d!\n",
                            __func__, isci_dev, status);

                return TMF_RESP_FUNC_FAILED;
        }
        if (isci_host != NULL)
                spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        /* Make sure all pending requests are able to be fully terminated. */
        isci_device_clear_reset_pending(isci_dev);

        /* Terminate in-progress I/O now. */
        isci_remote_device_nuke_requests(isci_dev);

        /* Call into the libsas default handler (which calls sas_phy_reset). */
        base_status = sas_eh_bus_reset_handler(cmd);

        if (base_status != SUCCESS) {

                /* There can be cases where the resets to individual devices
                 * behind an expander will fail because of an unplug of the
                 * expander itself.
                 */
                scmd_printk(KERN_WARNING, cmd,
                            "%s: sas_eh_bus_reset_handler(%p) returned %d!\n",
                            __func__, cmd, base_status);
        }

        /* WHAT TO DO HERE IF sas_phy_reset FAILS? */

        if (isci_host != NULL)
                spin_lock_irqsave(&isci_host->scic_lock, flags);
        status = scic_remote_device_reset_complete(to_sci_dev(isci_dev));

        if (isci_host != NULL)
                spin_unlock_irqrestore(&isci_host->scic_lock, flags);

        if (status != SCI_SUCCESS) {
                scmd_printk(KERN_WARNING, cmd,
                            "%s: scic_remote_device_reset_complete(%p) "
                            "returned %d!\n",
                            __func__, isci_dev, status);
        }
        /* WHAT TO DO HERE IF scic_remote_device_reset_complete FAILS? */

        dev_dbg(&cmd->device->sdev_gendev,
                "%s: cmd %p, isci_dev %p complete.\n",
                __func__, cmd, isci_dev);

        return TMF_RESP_FUNC_COMPLETE;
}