/*******************************************************************************
 * Filename: target_core_ua.c
 *
 * This file contains logic for SPC-3 Unit Attention emulation
 *
 * Copyright (c) 2009,2010 Rising Tide Systems
 * Copyright (c) 2009,2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>

#include <target/target_core_base.h>
#include <target/target_core_device.h>
#include <target/target_core_transport.h>
#include <target/target_core_fabric_ops.h>
#include <target/target_core_configfs.h>

#include "target_core_alua.h"
#include "target_core_hba.h"
#include "target_core_pr.h"
#include "target_core_ua.h"

int core_scsi3_ua_check(
        struct se_cmd *cmd,
        unsigned char *cdb)
{
        struct se_dev_entry *deve;
        struct se_session *sess = cmd->se_sess;
        struct se_node_acl *nacl;

        if (!sess)
                return 0;

        nacl = sess->se_node_acl;
        if (!nacl)
                return 0;

        deve = &nacl->device_list[cmd->orig_fe_lun];
        if (!atomic_read(&deve->ua_count))
                return 0;
        /*
         * From sam4r14, section 5.14 Unit attention condition:
         *
         * a) if an INQUIRY command enters the enabled command state, the
         *    device server shall process the INQUIRY command and shall neither
         *    report nor clear any unit attention condition;
         * b) if a REPORT LUNS command enters the enabled command state, the
         *    device server shall process the REPORT LUNS command and shall not
         *    report any unit attention condition;
         * e) if a REQUEST SENSE command enters the enabled command state while
         *    a unit attention condition exists for the SCSI initiator port
         *    associated with the I_T nexus on which the REQUEST SENSE command
         *    was received, then the device server shall process the command
         *    and either:
         */
        switch (cdb[0]) {
        case INQUIRY:
        case REPORT_LUNS:
        case REQUEST_SENSE:
                return 0;
        default:
                return -EINVAL;
        }

        return -EINVAL;
}

int core_scsi3_ua_allocate(
        struct se_node_acl *nacl,
        u32 unpacked_lun,
        u8 asc,
        u8 ascq)
{
        struct se_dev_entry *deve;
        struct se_ua *ua, *ua_p, *ua_tmp;
        /*
         * PASSTHROUGH OPS
         */
        if (!nacl)
                return -EINVAL;

        ua = kmem_cache_zalloc(se_ua_cache, GFP_ATOMIC);
        if (!ua) {
                pr_err("Unable to allocate struct se_ua\n");
                return -ENOMEM;
        }
        INIT_LIST_HEAD(&ua->ua_dev_list);
        INIT_LIST_HEAD(&ua->ua_nacl_list);

        ua->ua_nacl = nacl;
        ua->ua_asc = asc;
        ua->ua_ascq = ascq;

        spin_lock_irq(&nacl->device_list_lock);
        deve = &nacl->device_list[unpacked_lun];

        spin_lock(&deve->ua_lock);
        list_for_each_entry_safe(ua_p, ua_tmp, &deve->ua_list, ua_nacl_list) {
                /*
                 * Do not report the same UNIT ATTENTION twice..
                 */
                if ((ua_p->ua_asc == asc) && (ua_p->ua_ascq == ascq)) {
                        spin_unlock(&deve->ua_lock);
                        spin_unlock_irq(&nacl->device_list_lock);
                        kmem_cache_free(se_ua_cache, ua);
                        return 0;
                }
                /*
                 * Attach the highest priority Unit Attention to
                 * the head of the list following sam4r14,
                 * Section 5.14 Unit Attention Condition:
                 *
                 * POWER ON, RESET, OR BUS DEVICE RESET OCCURRED highest
                 * POWER ON OCCURRED or
                 * DEVICE INTERNAL RESET
                 * SCSI BUS RESET OCCURRED or
                 * MICROCODE HAS BEEN CHANGED or
                 * protocol specific
                 * BUS DEVICE RESET FUNCTION OCCURRED
                 * I_T NEXUS LOSS OCCURRED
                 * COMMANDS CLEARED BY POWER LOSS NOTIFICATION
                 * all others                                    Lowest
                 *
                 * Each of the ASCQ codes listed above are defined in
                 * the 29h ASC family, see spc4r17 Table D.1
                 */
                if (ua_p->ua_asc == 0x29) {
                        if ((asc == 0x29) && (ascq > ua_p->ua_ascq))
                                list_add(&ua->ua_nacl_list,
                                                &deve->ua_list);
                        else
                                list_add_tail(&ua->ua_nacl_list,
                                                &deve->ua_list);
                } else if (ua_p->ua_asc == 0x2a) {
                        /*
                         * Incoming Family 29h ASCQ codes will override
                         * Family 2AHh ASCQ codes for Unit Attention condition.
                         */
                        if ((asc == 0x29) || (ascq > ua_p->ua_asc))
                                list_add(&ua->ua_nacl_list,
                                        &deve->ua_list);
                        else
                                list_add_tail(&ua->ua_nacl_list,
                                                &deve->ua_list);
                } else
                        list_add_tail(&ua->ua_nacl_list,
                                &deve->ua_list);
                spin_unlock(&deve->ua_lock);
                spin_unlock_irq(&nacl->device_list_lock);

                atomic_inc(&deve->ua_count);
                smp_mb__after_atomic_inc();
                return 0;
        }
        list_add_tail(&ua->ua_nacl_list, &deve->ua_list);
        spin_unlock(&deve->ua_lock);
        spin_unlock_irq(&nacl->device_list_lock);

        pr_debug("[%s]: Allocated UNIT ATTENTION, mapped LUN: %u, ASC:"
                " 0x%02x, ASCQ: 0x%02x\n",
                nacl->se_tpg->se_tpg_tfo->get_fabric_name(), unpacked_lun,
                asc, ascq);

        atomic_inc(&deve->ua_count);
        smp_mb__after_atomic_inc();
        return 0;
}

void core_scsi3_ua_release_all(
        struct se_dev_entry *deve)
{
        struct se_ua *ua, *ua_p;

        spin_lock(&deve->ua_lock);
        list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
                list_del(&ua->ua_nacl_list);
                kmem_cache_free(se_ua_cache, ua);

                atomic_dec(&deve->ua_count);
                smp_mb__after_atomic_dec();
        }
        spin_unlock(&deve->ua_lock);
}

void core_scsi3_ua_for_check_condition(
        struct se_cmd *cmd,
        u8 *asc,
        u8 *ascq)
{
        struct se_device *dev = cmd->se_dev;
        struct se_dev_entry *deve;
        struct se_session *sess = cmd->se_sess;
        struct se_node_acl *nacl;
        struct se_ua *ua = NULL, *ua_p;
        int head = 1;

        if (!sess)
                return;

        nacl = sess->se_node_acl;
        if (!nacl)
                return;

        spin_lock_irq(&nacl->device_list_lock);
        deve = &nacl->device_list[cmd->orig_fe_lun];
        if (!atomic_read(&deve->ua_count)) {
                spin_unlock_irq(&nacl->device_list_lock);
                return;
        }
        /*
         * The highest priority Unit Attentions are placed at the head of the
         * struct se_dev_entry->ua_list, and will be returned in CHECK_CONDITION +
         * sense data for the received CDB.
         */
        spin_lock(&deve->ua_lock);
        list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
                /*
                 * For ua_intlck_ctrl code not equal to 00b, only report the
                 * highest priority UNIT_ATTENTION and ASC/ASCQ without
                 * clearing it.
                 */
                if (dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl != 0) {
                        *asc = ua->ua_asc;
                        *ascq = ua->ua_ascq;
                        break;
                }
                /*
                 * Otherwise for the default 00b, release the UNIT ATTENTION
                 * condition.  Return the ASC/ASCQ of the highest priority UA
                 * (head of the list) in the outgoing CHECK_CONDITION + sense.
                 */
                if (head) {
                        *asc = ua->ua_asc;
                        *ascq = ua->ua_ascq;
                        head = 0;
                }
                list_del(&ua->ua_nacl_list);
                kmem_cache_free(se_ua_cache, ua);

                atomic_dec(&deve->ua_count);
                smp_mb__after_atomic_dec();
        }
        spin_unlock(&deve->ua_lock);
        spin_unlock_irq(&nacl->device_list_lock);

        pr_debug("[%s]: %s UNIT ATTENTION condition with"
                " INTLCK_CTRL: %d, mapped LUN: %u, got CDB: 0x%02x"
                " reported ASC: 0x%02x, ASCQ: 0x%02x\n",
                nacl->se_tpg->se_tpg_tfo->get_fabric_name(),
                (dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl != 0) ? "Reporting" :
                "Releasing", dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl,
                cmd->orig_fe_lun, cmd->t_task_cdb[0], *asc, *ascq);
}

int core_scsi3_ua_clear_for_request_sense(
        struct se_cmd *cmd,
        u8 *asc,
        u8 *ascq)
{
        struct se_dev_entry *deve;
        struct se_session *sess = cmd->se_sess;
        struct se_node_acl *nacl;
        struct se_ua *ua = NULL, *ua_p;
        int head = 1;

        if (!sess)
                return -EINVAL;

        nacl = sess->se_node_acl;
        if (!nacl)
                return -EINVAL;

        spin_lock_irq(&nacl->device_list_lock);
        deve = &nacl->device_list[cmd->orig_fe_lun];
        if (!atomic_read(&deve->ua_count)) {
                spin_unlock_irq(&nacl->device_list_lock);
                return -EPERM;
        }
        /*
         * The highest priority Unit Attentions are placed at the head of the
         * struct se_dev_entry->ua_list.  The First (and hence highest priority)
         * ASC/ASCQ will be returned in REQUEST_SENSE payload data for the
         * matching struct se_lun.
         *
         * Once the returning ASC/ASCQ values are set, we go ahead and
         * release all of the Unit Attention conditions for the associated
         * struct se_lun.
         */
        spin_lock(&deve->ua_lock);
        list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
                if (head) {
                        *asc = ua->ua_asc;
                        *ascq = ua->ua_ascq;
                        head = 0;
                }
                list_del(&ua->ua_nacl_list);
                kmem_cache_free(se_ua_cache, ua);

                atomic_dec(&deve->ua_count);
                smp_mb__after_atomic_dec();
        }
        spin_unlock(&deve->ua_lock);
        spin_unlock_irq(&nacl->device_list_lock);

        pr_debug("[%s]: Released UNIT ATTENTION condition, mapped"
                " LUN: %u, got REQUEST_SENSE reported ASC: 0x%02x,"
                " ASCQ: 0x%02x\n", nacl->se_tpg->se_tpg_tfo->get_fabric_name(),
                cmd->orig_fe_lun, *asc, *ascq);

        return (head) ? -EPERM : 0;
}