// SPDX-License-Identifier: GPL-2.0
/*
 * zfcp device driver
 *
 * Error Recovery Procedures (ERP).
 *
 * Copyright IBM Corp. 2002, 2020
 */

#define KMSG_COMPONENT "zfcp"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kthread.h>
#include <linux/bug.h>
#include "zfcp_ext.h"
#include "zfcp_reqlist.h"
#include "zfcp_diag.h"

#define ZFCP_MAX_ERPS                   3

enum zfcp_erp_act_flags {
        ZFCP_STATUS_ERP_TIMEDOUT        = 0x10000000,
        ZFCP_STATUS_ERP_CLOSE_ONLY      = 0x01000000,
        ZFCP_STATUS_ERP_DISMISSED       = 0x00200000,
        ZFCP_STATUS_ERP_LOWMEM          = 0x00400000,
        ZFCP_STATUS_ERP_NO_REF          = 0x00800000,
};

/*
 * Eyecatcher pseudo flag to bitwise or-combine with enum zfcp_erp_act_type.
 * Used to indicate that an ERP action could not be set up despite a detected
 * need for some recovery.
 */
#define ZFCP_ERP_ACTION_NONE            0xc0
/*
 * Eyecatcher pseudo flag to bitwise or-combine with enum zfcp_erp_act_type.
 * Used to indicate that ERP not needed because the object has
 * ZFCP_STATUS_COMMON_ERP_FAILED.
 */
#define ZFCP_ERP_ACTION_FAILED          0xe0

enum zfcp_erp_act_result {
        ZFCP_ERP_SUCCEEDED = 0,
        ZFCP_ERP_FAILED    = 1,
        ZFCP_ERP_CONTINUES = 2,
        ZFCP_ERP_EXIT      = 3,
        ZFCP_ERP_DISMISSED = 4,
        ZFCP_ERP_NOMEM     = 5,
};

static void zfcp_erp_adapter_block(struct zfcp_adapter *adapter, int mask)
{
        zfcp_erp_clear_adapter_status(adapter,
                                       ZFCP_STATUS_COMMON_UNBLOCKED | mask);
}

static bool zfcp_erp_action_is_running(struct zfcp_erp_action *act)
{
        struct zfcp_erp_action *curr_act;

        list_for_each_entry(curr_act, &act->adapter->erp_running_head, list)
                if (act == curr_act)
                        return true;
        return false;
}

static void zfcp_erp_action_ready(struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;

        list_move(&act->list, &adapter->erp_ready_head);
        zfcp_dbf_rec_run("erardy1", act);
        wake_up(&adapter->erp_ready_wq);
        zfcp_dbf_rec_run("erardy2", act);
}

static void zfcp_erp_action_dismiss(struct zfcp_erp_action *act)
{
        act->status |= ZFCP_STATUS_ERP_DISMISSED;
        if (zfcp_erp_action_is_running(act))
                zfcp_erp_action_ready(act);
}

static void zfcp_erp_action_dismiss_lun(struct scsi_device *sdev)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_ERP_INUSE)
                zfcp_erp_action_dismiss(&zfcp_sdev->erp_action);
}

static void zfcp_erp_action_dismiss_port(struct zfcp_port *port)
{
        struct scsi_device *sdev;

        if (atomic_read(&port->status) & ZFCP_STATUS_COMMON_ERP_INUSE)
                zfcp_erp_action_dismiss(&port->erp_action);
        else {
                spin_lock(port->adapter->scsi_host->host_lock);
                __shost_for_each_device(sdev, port->adapter->scsi_host)
                        if (sdev_to_zfcp(sdev)->port == port)
                                zfcp_erp_action_dismiss_lun(sdev);
                spin_unlock(port->adapter->scsi_host->host_lock);
        }
}

static void zfcp_erp_action_dismiss_adapter(struct zfcp_adapter *adapter)
{
        struct zfcp_port *port;

        if (atomic_read(&adapter->status) & ZFCP_STATUS_COMMON_ERP_INUSE)
                zfcp_erp_action_dismiss(&adapter->erp_action);
        else {
                read_lock(&adapter->port_list_lock);
                list_for_each_entry(port, &adapter->port_list, list)
                    zfcp_erp_action_dismiss_port(port);
                read_unlock(&adapter->port_list_lock);
        }
}

static enum zfcp_erp_act_type zfcp_erp_handle_failed(
        enum zfcp_erp_act_type want, struct zfcp_adapter *adapter,
        struct zfcp_port *port, struct scsi_device *sdev)
{
        enum zfcp_erp_act_type need = want;
        struct zfcp_scsi_dev *zsdev;

        switch (want) {
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                zsdev = sdev_to_zfcp(sdev);
                if (atomic_read(&zsdev->status) & ZFCP_STATUS_COMMON_ERP_FAILED)
                        need = 0;
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                if (atomic_read(&port->status) & ZFCP_STATUS_COMMON_ERP_FAILED)
                        need = 0;
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                if (atomic_read(&port->status) &
                    ZFCP_STATUS_COMMON_ERP_FAILED) {
                        need = 0;
                        /* ensure propagation of failed status to new devices */
                        zfcp_erp_set_port_status(
                                port, ZFCP_STATUS_COMMON_ERP_FAILED);
                }
                break;
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                if (atomic_read(&adapter->status) &
                    ZFCP_STATUS_COMMON_ERP_FAILED) {
                        need = 0;
                        /* ensure propagation of failed status to new devices */
                        zfcp_erp_set_adapter_status(
                                adapter, ZFCP_STATUS_COMMON_ERP_FAILED);
                }
                break;
        }

        return need;
}

static enum zfcp_erp_act_type zfcp_erp_required_act(enum zfcp_erp_act_type want,
                                 struct zfcp_adapter *adapter,
                                 struct zfcp_port *port,
                                 struct scsi_device *sdev)
{
        enum zfcp_erp_act_type need = want;
        int l_status, p_status, a_status;
        struct zfcp_scsi_dev *zfcp_sdev;

        switch (want) {
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                zfcp_sdev = sdev_to_zfcp(sdev);
                l_status = atomic_read(&zfcp_sdev->status);
                if (l_status & ZFCP_STATUS_COMMON_ERP_INUSE)
                        return 0;
                p_status = atomic_read(&port->status);
                if (!(p_status & ZFCP_STATUS_COMMON_RUNNING) ||
                    p_status & ZFCP_STATUS_COMMON_ERP_FAILED)
                        return 0;
                if (!(p_status & ZFCP_STATUS_COMMON_UNBLOCKED))
                        need = ZFCP_ERP_ACTION_REOPEN_PORT;
                fallthrough;
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                p_status = atomic_read(&port->status);
                if (!(p_status & ZFCP_STATUS_COMMON_OPEN))
                        need = ZFCP_ERP_ACTION_REOPEN_PORT;
                fallthrough;
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                p_status = atomic_read(&port->status);
                if (p_status & ZFCP_STATUS_COMMON_ERP_INUSE)
                        return 0;
                a_status = atomic_read(&adapter->status);
                if (!(a_status & ZFCP_STATUS_COMMON_RUNNING) ||
                    a_status & ZFCP_STATUS_COMMON_ERP_FAILED)
                        return 0;
                if (p_status & ZFCP_STATUS_COMMON_NOESC)
                        return need;
                if (!(a_status & ZFCP_STATUS_COMMON_UNBLOCKED))
                        need = ZFCP_ERP_ACTION_REOPEN_ADAPTER;
                fallthrough;
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                a_status = atomic_read(&adapter->status);
                if (a_status & ZFCP_STATUS_COMMON_ERP_INUSE)
                        return 0;
                if (!(a_status & ZFCP_STATUS_COMMON_RUNNING) &&
                    !(a_status & ZFCP_STATUS_COMMON_OPEN))
                        return 0; /* shutdown requested for closed adapter */
        }

        return need;
}

static struct zfcp_erp_action *zfcp_erp_setup_act(enum zfcp_erp_act_type need,
                                                  u32 act_status,
                                                  struct zfcp_adapter *adapter,
                                                  struct zfcp_port *port,
                                                  struct scsi_device *sdev)
{
        struct zfcp_erp_action *erp_action;
        struct zfcp_scsi_dev *zfcp_sdev;

        if (WARN_ON_ONCE(need != ZFCP_ERP_ACTION_REOPEN_LUN &&
                         need != ZFCP_ERP_ACTION_REOPEN_PORT &&
                         need != ZFCP_ERP_ACTION_REOPEN_PORT_FORCED &&
                         need != ZFCP_ERP_ACTION_REOPEN_ADAPTER))
                return NULL;

        switch (need) {
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                zfcp_sdev = sdev_to_zfcp(sdev);
                if (!(act_status & ZFCP_STATUS_ERP_NO_REF))
                        if (scsi_device_get(sdev))
                                return NULL;
                atomic_or(ZFCP_STATUS_COMMON_ERP_INUSE,
                                &zfcp_sdev->status);
                erp_action = &zfcp_sdev->erp_action;
                WARN_ON_ONCE(erp_action->port != port);
                WARN_ON_ONCE(erp_action->sdev != sdev);
                if (!(atomic_read(&zfcp_sdev->status) &
                      ZFCP_STATUS_COMMON_RUNNING))
                        act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;

        case ZFCP_ERP_ACTION_REOPEN_PORT:
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                if (!get_device(&port->dev))
                        return NULL;
                zfcp_erp_action_dismiss_port(port);
                atomic_or(ZFCP_STATUS_COMMON_ERP_INUSE, &port->status);
                erp_action = &port->erp_action;
                WARN_ON_ONCE(erp_action->port != port);
                WARN_ON_ONCE(erp_action->sdev != NULL);
                if (!(atomic_read(&port->status) & ZFCP_STATUS_COMMON_RUNNING))
                        act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;

        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                kref_get(&adapter->ref);
                zfcp_erp_action_dismiss_adapter(adapter);
                atomic_or(ZFCP_STATUS_COMMON_ERP_INUSE, &adapter->status);
                erp_action = &adapter->erp_action;
                WARN_ON_ONCE(erp_action->port != NULL);
                WARN_ON_ONCE(erp_action->sdev != NULL);
                if (!(atomic_read(&adapter->status) &
                      ZFCP_STATUS_COMMON_RUNNING))
                        act_status |= ZFCP_STATUS_ERP_CLOSE_ONLY;
                break;
        }

        WARN_ON_ONCE(erp_action->adapter != adapter);
        memset(&erp_action->list, 0, sizeof(erp_action->list));
        memset(&erp_action->timer, 0, sizeof(erp_action->timer));
        erp_action->step = ZFCP_ERP_STEP_UNINITIALIZED;
        erp_action->fsf_req_id = 0;
        erp_action->type = need;
        erp_action->status = act_status;

        return erp_action;
}

static void zfcp_erp_action_enqueue(enum zfcp_erp_act_type want,
                                    struct zfcp_adapter *adapter,
                                    struct zfcp_port *port,
                                    struct scsi_device *sdev,
                                    char *dbftag, u32 act_status)
{
        enum zfcp_erp_act_type need;
        struct zfcp_erp_action *act;

        need = zfcp_erp_handle_failed(want, adapter, port, sdev);
        if (!need) {
                need = ZFCP_ERP_ACTION_FAILED; /* marker for trace */
                goto out;
        }

        if (!adapter->erp_thread) {
                need = ZFCP_ERP_ACTION_NONE; /* marker for trace */
                goto out;
        }

        need = zfcp_erp_required_act(want, adapter, port, sdev);
        if (!need)
                goto out;

        act = zfcp_erp_setup_act(need, act_status, adapter, port, sdev);
        if (!act) {
                need |= ZFCP_ERP_ACTION_NONE; /* marker for trace */
                goto out;
        }
        atomic_or(ZFCP_STATUS_ADAPTER_ERP_PENDING, &adapter->status);
        ++adapter->erp_total_count;
        list_add_tail(&act->list, &adapter->erp_ready_head);
        wake_up(&adapter->erp_ready_wq);
 out:
        zfcp_dbf_rec_trig(dbftag, adapter, port, sdev, want, need);
}

void zfcp_erp_port_forced_no_port_dbf(char *dbftag,
                                      struct zfcp_adapter *adapter,
                                      u64 port_name, u32 port_id)
{
        unsigned long flags;
        static /* don't waste stack */ struct zfcp_port tmpport;

        write_lock_irqsave(&adapter->erp_lock, flags);
        /* Stand-in zfcp port with fields just good enough for
         * zfcp_dbf_rec_trig() and zfcp_dbf_set_common().
         * Under lock because tmpport is static.
         */
        atomic_set(&tmpport.status, -1); /* unknown */
        tmpport.wwpn = port_name;
        tmpport.d_id = port_id;
        zfcp_dbf_rec_trig(dbftag, adapter, &tmpport, NULL,
                          ZFCP_ERP_ACTION_REOPEN_PORT_FORCED,
                          ZFCP_ERP_ACTION_NONE);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void _zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter,
                                    int clear_mask, char *dbftag)
{
        zfcp_erp_adapter_block(adapter, clear_mask);
        zfcp_scsi_schedule_rports_block(adapter);

        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER,
                                adapter, NULL, NULL, dbftag, 0);
}

/**
 * zfcp_erp_adapter_reopen - Reopen adapter.
 * @adapter: Adapter to reopen.
 * @clear: Status flags to clear.
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter, int clear,
                             char *dbftag)
{
        unsigned long flags;

        zfcp_erp_adapter_block(adapter, clear);
        zfcp_scsi_schedule_rports_block(adapter);

        write_lock_irqsave(&adapter->erp_lock, flags);
        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_ADAPTER, adapter,
                                NULL, NULL, dbftag, 0);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

/**
 * zfcp_erp_adapter_shutdown - Shutdown adapter.
 * @adapter: Adapter to shut down.
 * @clear: Status flags to clear.
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_adapter_shutdown(struct zfcp_adapter *adapter, int clear,
                               char *dbftag)
{
        int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
        zfcp_erp_adapter_reopen(adapter, clear | flags, dbftag);
}

/**
 * zfcp_erp_port_shutdown - Shutdown port
 * @port: Port to shut down.
 * @clear: Status flags to clear.
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_port_shutdown(struct zfcp_port *port, int clear, char *dbftag)
{
        int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
        zfcp_erp_port_reopen(port, clear | flags, dbftag);
}

static void zfcp_erp_port_block(struct zfcp_port *port, int clear)
{
        zfcp_erp_clear_port_status(port,
                                    ZFCP_STATUS_COMMON_UNBLOCKED | clear);
}

static void _zfcp_erp_port_forced_reopen(struct zfcp_port *port, int clear,
                                         char *dbftag)
{
        zfcp_erp_port_block(port, clear);
        zfcp_scsi_schedule_rport_block(port);

        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT_FORCED,
                                port->adapter, port, NULL, dbftag, 0);
}

/**
 * zfcp_erp_port_forced_reopen - Forced close of port and open again
 * @port: Port to force close and to reopen.
 * @clear: Status flags to clear.
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_port_forced_reopen(struct zfcp_port *port, int clear,
                                 char *dbftag)
{
        unsigned long flags;
        struct zfcp_adapter *adapter = port->adapter;

        write_lock_irqsave(&adapter->erp_lock, flags);
        _zfcp_erp_port_forced_reopen(port, clear, dbftag);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void _zfcp_erp_port_reopen(struct zfcp_port *port, int clear,
                                  char *dbftag)
{
        zfcp_erp_port_block(port, clear);
        zfcp_scsi_schedule_rport_block(port);

        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_PORT,
                                port->adapter, port, NULL, dbftag, 0);
}

/**
 * zfcp_erp_port_reopen - trigger remote port recovery
 * @port: port to recover
 * @clear: flags in port status to be cleared
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_port_reopen(struct zfcp_port *port, int clear, char *dbftag)
{
        unsigned long flags;
        struct zfcp_adapter *adapter = port->adapter;

        write_lock_irqsave(&adapter->erp_lock, flags);
        _zfcp_erp_port_reopen(port, clear, dbftag);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void zfcp_erp_lun_block(struct scsi_device *sdev, int clear_mask)
{
        zfcp_erp_clear_lun_status(sdev,
                                  ZFCP_STATUS_COMMON_UNBLOCKED | clear_mask);
}

static void _zfcp_erp_lun_reopen(struct scsi_device *sdev, int clear,
                                 char *dbftag, u32 act_status)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);
        struct zfcp_adapter *adapter = zfcp_sdev->port->adapter;

        zfcp_erp_lun_block(sdev, clear);

        zfcp_erp_action_enqueue(ZFCP_ERP_ACTION_REOPEN_LUN, adapter,
                                zfcp_sdev->port, sdev, dbftag, act_status);
}

/**
 * zfcp_erp_lun_reopen - initiate reopen of a LUN
 * @sdev: SCSI device / LUN to be reopened
 * @clear: specifies flags in LUN status to be cleared
 * @dbftag: Tag for debug trace event.
 *
 * Return: 0 on success, < 0 on error
 */
void zfcp_erp_lun_reopen(struct scsi_device *sdev, int clear, char *dbftag)
{
        unsigned long flags;
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);
        struct zfcp_port *port = zfcp_sdev->port;
        struct zfcp_adapter *adapter = port->adapter;

        write_lock_irqsave(&adapter->erp_lock, flags);
        _zfcp_erp_lun_reopen(sdev, clear, dbftag, 0);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

/**
 * zfcp_erp_lun_shutdown - Shutdown LUN
 * @sdev: SCSI device / LUN to shut down.
 * @clear: Status flags to clear.
 * @dbftag: Tag for debug trace event.
 */
void zfcp_erp_lun_shutdown(struct scsi_device *sdev, int clear, char *dbftag)
{
        int flags = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;
        zfcp_erp_lun_reopen(sdev, clear | flags, dbftag);
}

/**
 * zfcp_erp_lun_shutdown_wait - Shutdown LUN and wait for erp completion
 * @sdev: SCSI device / LUN to shut down.
 * @dbftag: Tag for debug trace event.
 *
 * Do not acquire a reference for the LUN when creating the ERP
 * action. It is safe, because this function waits for the ERP to
 * complete first. This allows to shutdown the LUN, even when the SCSI
 * device is in the state SDEV_DEL when scsi_device_get will fail.
 */
void zfcp_erp_lun_shutdown_wait(struct scsi_device *sdev, char *dbftag)
{
        unsigned long flags;
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);
        struct zfcp_port *port = zfcp_sdev->port;
        struct zfcp_adapter *adapter = port->adapter;
        int clear = ZFCP_STATUS_COMMON_RUNNING | ZFCP_STATUS_COMMON_ERP_FAILED;

        write_lock_irqsave(&adapter->erp_lock, flags);
        _zfcp_erp_lun_reopen(sdev, clear, dbftag, ZFCP_STATUS_ERP_NO_REF);
        write_unlock_irqrestore(&adapter->erp_lock, flags);

        zfcp_erp_wait(adapter);
}

static int zfcp_erp_status_change_set(unsigned long mask, atomic_t *status)
{
        return (atomic_read(status) ^ mask) & mask;
}

static void zfcp_erp_adapter_unblock(struct zfcp_adapter *adapter)
{
        if (zfcp_erp_status_change_set(ZFCP_STATUS_COMMON_UNBLOCKED,
                                       &adapter->status))
                zfcp_dbf_rec_run("eraubl1", &adapter->erp_action);
        atomic_or(ZFCP_STATUS_COMMON_UNBLOCKED, &adapter->status);
}

static void zfcp_erp_port_unblock(struct zfcp_port *port)
{
        if (zfcp_erp_status_change_set(ZFCP_STATUS_COMMON_UNBLOCKED,
                                       &port->status))
                zfcp_dbf_rec_run("erpubl1", &port->erp_action);
        atomic_or(ZFCP_STATUS_COMMON_UNBLOCKED, &port->status);
}

static void zfcp_erp_lun_unblock(struct scsi_device *sdev)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        if (zfcp_erp_status_change_set(ZFCP_STATUS_COMMON_UNBLOCKED,
                                       &zfcp_sdev->status))
                zfcp_dbf_rec_run("erlubl1", &sdev_to_zfcp(sdev)->erp_action);
        atomic_or(ZFCP_STATUS_COMMON_UNBLOCKED, &zfcp_sdev->status);
}

static void zfcp_erp_action_to_running(struct zfcp_erp_action *erp_action)
{
        list_move(&erp_action->list, &erp_action->adapter->erp_running_head);
        zfcp_dbf_rec_run("erator1", erp_action);
}

static void zfcp_erp_strategy_check_fsfreq(struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;
        struct zfcp_fsf_req *req;

        if (!act->fsf_req_id)
                return;

        spin_lock(&adapter->req_list->lock);
        req = _zfcp_reqlist_find(adapter->req_list, act->fsf_req_id);
        if (req && req->erp_action == act) {
                if (act->status & (ZFCP_STATUS_ERP_DISMISSED |
                                   ZFCP_STATUS_ERP_TIMEDOUT)) {
                        req->status |= ZFCP_STATUS_FSFREQ_DISMISSED;
                        zfcp_dbf_rec_run("erscf_1", act);
                        /* lock-free concurrent access with
                         * zfcp_erp_timeout_handler()
                         */
                        WRITE_ONCE(req->erp_action, NULL);
                }
                if (act->status & ZFCP_STATUS_ERP_TIMEDOUT)
                        zfcp_dbf_rec_run("erscf_2", act);
                if (req->status & ZFCP_STATUS_FSFREQ_DISMISSED)
                        act->fsf_req_id = 0;
        } else
                act->fsf_req_id = 0;
        spin_unlock(&adapter->req_list->lock);
}

/**
 * zfcp_erp_notify - Trigger ERP action.
 * @erp_action: ERP action to continue.
 * @set_mask: ERP action status flags to set.
 */
void zfcp_erp_notify(struct zfcp_erp_action *erp_action, unsigned long set_mask)
{
        struct zfcp_adapter *adapter = erp_action->adapter;
        unsigned long flags;

        write_lock_irqsave(&adapter->erp_lock, flags);
        if (zfcp_erp_action_is_running(erp_action)) {
                erp_action->status |= set_mask;
                zfcp_erp_action_ready(erp_action);
        }
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

/**
 * zfcp_erp_timeout_handler - Trigger ERP action from timed out ERP request
 * @t: timer list entry embedded in zfcp FSF request
 */
void zfcp_erp_timeout_handler(struct timer_list *t)
{
        struct zfcp_fsf_req *fsf_req = from_timer(fsf_req, t, timer);
        struct zfcp_erp_action *act;

        if (fsf_req->status & ZFCP_STATUS_FSFREQ_DISMISSED)
                return;
        /* lock-free concurrent access with zfcp_erp_strategy_check_fsfreq() */
        act = READ_ONCE(fsf_req->erp_action);
        if (!act)
                return;
        zfcp_erp_notify(act, ZFCP_STATUS_ERP_TIMEDOUT);
}

static void zfcp_erp_memwait_handler(struct timer_list *t)
{
        struct zfcp_erp_action *act = from_timer(act, t, timer);

        zfcp_erp_notify(act, 0);
}

static void zfcp_erp_strategy_memwait(struct zfcp_erp_action *erp_action)
{
        timer_setup(&erp_action->timer, zfcp_erp_memwait_handler, 0);
        erp_action->timer.expires = jiffies + HZ;
        add_timer(&erp_action->timer);
}

void zfcp_erp_port_forced_reopen_all(struct zfcp_adapter *adapter,
                                     int clear, char *dbftag)
{
        unsigned long flags;
        struct zfcp_port *port;

        write_lock_irqsave(&adapter->erp_lock, flags);
        read_lock(&adapter->port_list_lock);
        list_for_each_entry(port, &adapter->port_list, list)
                _zfcp_erp_port_forced_reopen(port, clear, dbftag);
        read_unlock(&adapter->port_list_lock);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void _zfcp_erp_port_reopen_all(struct zfcp_adapter *adapter,
                                      int clear, char *dbftag)
{
        struct zfcp_port *port;

        read_lock(&adapter->port_list_lock);
        list_for_each_entry(port, &adapter->port_list, list)
                _zfcp_erp_port_reopen(port, clear, dbftag);
        read_unlock(&adapter->port_list_lock);
}

static void _zfcp_erp_lun_reopen_all(struct zfcp_port *port, int clear,
                                     char *dbftag)
{
        struct scsi_device *sdev;

        spin_lock(port->adapter->scsi_host->host_lock);
        __shost_for_each_device(sdev, port->adapter->scsi_host)
                if (sdev_to_zfcp(sdev)->port == port)
                        _zfcp_erp_lun_reopen(sdev, clear, dbftag, 0);
        spin_unlock(port->adapter->scsi_host->host_lock);
}

static void zfcp_erp_strategy_followup_failed(struct zfcp_erp_action *act)
{
        switch (act->type) {
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                _zfcp_erp_adapter_reopen(act->adapter, 0, "ersff_1");
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                _zfcp_erp_port_forced_reopen(act->port, 0, "ersff_2");
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                _zfcp_erp_port_reopen(act->port, 0, "ersff_3");
                break;
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                _zfcp_erp_lun_reopen(act->sdev, 0, "ersff_4", 0);
                break;
        }
}

static void zfcp_erp_strategy_followup_success(struct zfcp_erp_action *act)
{
        switch (act->type) {
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                _zfcp_erp_port_reopen_all(act->adapter, 0, "ersfs_1");
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                _zfcp_erp_port_reopen(act->port, 0, "ersfs_2");
                break;
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                _zfcp_erp_lun_reopen_all(act->port, 0, "ersfs_3");
                break;
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                /* NOP */
                break;
        }
}

static void zfcp_erp_wakeup(struct zfcp_adapter *adapter)
{
        unsigned long flags;

        read_lock_irqsave(&adapter->erp_lock, flags);
        if (list_empty(&adapter->erp_ready_head) &&
            list_empty(&adapter->erp_running_head)) {
                        atomic_andnot(ZFCP_STATUS_ADAPTER_ERP_PENDING,
                                          &adapter->status);
                        wake_up(&adapter->erp_done_wqh);
        }
        read_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void zfcp_erp_enqueue_ptp_port(struct zfcp_adapter *adapter)
{
        struct zfcp_port *port;
        port = zfcp_port_enqueue(adapter, adapter->peer_wwpn, 0,
                                 adapter->peer_d_id);
        if (IS_ERR(port)) /* error or port already attached */
                return;
        zfcp_erp_port_reopen(port, 0, "ereptp1");
}

static enum zfcp_erp_act_result zfcp_erp_adapter_strat_fsf_xconf(
        struct zfcp_erp_action *erp_action)
{
        int retries;
        int sleep = 1;
        struct zfcp_adapter *adapter = erp_action->adapter;

        atomic_andnot(ZFCP_STATUS_ADAPTER_XCONFIG_OK, &adapter->status);

        for (retries = 7; retries; retries--) {
                atomic_andnot(ZFCP_STATUS_ADAPTER_HOST_CON_INIT,
                                  &adapter->status);
                write_lock_irq(&adapter->erp_lock);
                zfcp_erp_action_to_running(erp_action);
                write_unlock_irq(&adapter->erp_lock);
                if (zfcp_fsf_exchange_config_data(erp_action)) {
                        atomic_andnot(ZFCP_STATUS_ADAPTER_HOST_CON_INIT,
                                          &adapter->status);
                        return ZFCP_ERP_FAILED;
                }

                wait_event(adapter->erp_ready_wq,
                           !list_empty(&adapter->erp_ready_head));
                if (erp_action->status & ZFCP_STATUS_ERP_TIMEDOUT)
                        break;

                if (!(atomic_read(&adapter->status) &
                      ZFCP_STATUS_ADAPTER_HOST_CON_INIT))
                        break;

                ssleep(sleep);
                sleep *= 2;
        }

        atomic_andnot(ZFCP_STATUS_ADAPTER_HOST_CON_INIT,
                          &adapter->status);

        if (!(atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_XCONFIG_OK))
                return ZFCP_ERP_FAILED;

        return ZFCP_ERP_SUCCEEDED;
}

static void
zfcp_erp_adapter_strategy_open_ptp_port(struct zfcp_adapter *const adapter)
{
        if (fc_host_port_type(adapter->scsi_host) == FC_PORTTYPE_PTP)
                zfcp_erp_enqueue_ptp_port(adapter);
}

static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open_fsf_xport(
        struct zfcp_erp_action *act)
{
        int ret;
        struct zfcp_adapter *adapter = act->adapter;

        write_lock_irq(&adapter->erp_lock);
        zfcp_erp_action_to_running(act);
        write_unlock_irq(&adapter->erp_lock);

        ret = zfcp_fsf_exchange_port_data(act);
        if (ret == -EOPNOTSUPP)
                return ZFCP_ERP_SUCCEEDED;
        if (ret)
                return ZFCP_ERP_FAILED;

        zfcp_dbf_rec_run("erasox1", act);
        wait_event(adapter->erp_ready_wq,
                   !list_empty(&adapter->erp_ready_head));
        zfcp_dbf_rec_run("erasox2", act);
        if (act->status & ZFCP_STATUS_ERP_TIMEDOUT)
                return ZFCP_ERP_FAILED;

        return ZFCP_ERP_SUCCEEDED;
}

static enum zfcp_erp_act_result
zfcp_erp_adapter_strategy_alloc_shost(struct zfcp_adapter *const adapter)
{
        struct zfcp_diag_adapter_config_data *const config_data =
                &adapter->diagnostics->config_data;
        struct zfcp_diag_adapter_port_data *const port_data =
                &adapter->diagnostics->port_data;
        unsigned long flags;
        int rc;

        rc = zfcp_scsi_adapter_register(adapter);
        if (rc == -EEXIST)
                return ZFCP_ERP_SUCCEEDED;
        else if (rc)
                return ZFCP_ERP_FAILED;

        /*
         * We allocated the shost for the first time. Before it was NULL,
         * and so we deferred all updates in the xconf- and xport-data
         * handlers. We need to make up for that now, and make all the updates
         * that would have been done before.
         *
         * We can be sure that xconf- and xport-data succeeded, because
         * otherwise this function is not called. But they might have been
         * incomplete.
         */

        spin_lock_irqsave(&config_data->header.access_lock, flags);
        zfcp_scsi_shost_update_config_data(adapter, &config_data->data,
                                           !!config_data->header.incomplete);
        spin_unlock_irqrestore(&config_data->header.access_lock, flags);

        if (adapter->adapter_features & FSF_FEATURE_HBAAPI_MANAGEMENT) {
                spin_lock_irqsave(&port_data->header.access_lock, flags);
                zfcp_scsi_shost_update_port_data(adapter, &port_data->data);
                spin_unlock_irqrestore(&port_data->header.access_lock, flags);
        }

        /*
         * There is a remote possibility that the 'Exchange Port Data' request
         * reports a different connectivity status than 'Exchange Config Data'.
         * But any change to the connectivity status of the local optic that
         * happens after the initial xconf request is expected to be reported
         * to us, as soon as we post Status Read Buffers to the FCP channel
         * firmware after this function. So any resulting inconsistency will
         * only be momentary.
         */
        if (config_data->header.incomplete)
                zfcp_fsf_fc_host_link_down(adapter);

        return ZFCP_ERP_SUCCEEDED;
}

static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open_fsf(
        struct zfcp_erp_action *act)
{
        if (zfcp_erp_adapter_strat_fsf_xconf(act) == ZFCP_ERP_FAILED)
                return ZFCP_ERP_FAILED;

        if (zfcp_erp_adapter_strategy_open_fsf_xport(act) == ZFCP_ERP_FAILED)
                return ZFCP_ERP_FAILED;

        if (zfcp_erp_adapter_strategy_alloc_shost(act->adapter) ==
            ZFCP_ERP_FAILED)
                return ZFCP_ERP_FAILED;

        zfcp_erp_adapter_strategy_open_ptp_port(act->adapter);

        if (mempool_resize(act->adapter->pool.sr_data,
                           act->adapter->stat_read_buf_num))
                return ZFCP_ERP_FAILED;

        if (mempool_resize(act->adapter->pool.status_read_req,
                           act->adapter->stat_read_buf_num))
                return ZFCP_ERP_FAILED;

        atomic_set(&act->adapter->stat_miss, act->adapter->stat_read_buf_num);
        if (zfcp_status_read_refill(act->adapter))
                return ZFCP_ERP_FAILED;

        return ZFCP_ERP_SUCCEEDED;
}

static void zfcp_erp_adapter_strategy_close(struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;

        /* close queues to ensure that buffers are not accessed by adapter */
        zfcp_qdio_close(adapter->qdio);
        zfcp_fsf_req_dismiss_all(adapter);
        adapter->fsf_req_seq_no = 0;
        zfcp_fc_wka_ports_force_offline(adapter->gs);
        /* all ports and LUNs are closed */
        zfcp_erp_clear_adapter_status(adapter, ZFCP_STATUS_COMMON_OPEN);

        atomic_andnot(ZFCP_STATUS_ADAPTER_XCONFIG_OK |
                          ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED, &adapter->status);
}

static enum zfcp_erp_act_result zfcp_erp_adapter_strategy_open(
        struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;

        if (zfcp_qdio_open(adapter->qdio)) {
                atomic_andnot(ZFCP_STATUS_ADAPTER_XCONFIG_OK |
                                  ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED,
                                  &adapter->status);
                return ZFCP_ERP_FAILED;
        }

        if (zfcp_erp_adapter_strategy_open_fsf(act)) {
                zfcp_erp_adapter_strategy_close(act);
                return ZFCP_ERP_FAILED;
        }

        atomic_or(ZFCP_STATUS_COMMON_OPEN, &adapter->status);

        return ZFCP_ERP_SUCCEEDED;
}

static enum zfcp_erp_act_result zfcp_erp_adapter_strategy(
        struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;

        if (atomic_read(&adapter->status) & ZFCP_STATUS_COMMON_OPEN) {
                zfcp_erp_adapter_strategy_close(act);
                if (act->status & ZFCP_STATUS_ERP_CLOSE_ONLY)
                        return ZFCP_ERP_EXIT;
        }

        if (zfcp_erp_adapter_strategy_open(act)) {
                ssleep(8);
                return ZFCP_ERP_FAILED;
        }

        return ZFCP_ERP_SUCCEEDED;
}

static enum zfcp_erp_act_result zfcp_erp_port_forced_strategy_close(
        struct zfcp_erp_action *act)
{
        int retval;

        retval = zfcp_fsf_close_physical_port(act);
        if (retval == -ENOMEM)
                return ZFCP_ERP_NOMEM;
        act->step = ZFCP_ERP_STEP_PHYS_PORT_CLOSING;
        if (retval)
                return ZFCP_ERP_FAILED;

        return ZFCP_ERP_CONTINUES;
}

static enum zfcp_erp_act_result zfcp_erp_port_forced_strategy(
        struct zfcp_erp_action *erp_action)
{
        struct zfcp_port *port = erp_action->port;
        int status = atomic_read(&port->status);

        switch (erp_action->step) {
        case ZFCP_ERP_STEP_UNINITIALIZED:
                if ((status & ZFCP_STATUS_PORT_PHYS_OPEN) &&
                    (status & ZFCP_STATUS_COMMON_OPEN))
                        return zfcp_erp_port_forced_strategy_close(erp_action);
                else
                        return ZFCP_ERP_FAILED;

        case ZFCP_ERP_STEP_PHYS_PORT_CLOSING:
                if (!(status & ZFCP_STATUS_PORT_PHYS_OPEN))
                        return ZFCP_ERP_SUCCEEDED;
                break;
        case ZFCP_ERP_STEP_PORT_CLOSING:
        case ZFCP_ERP_STEP_PORT_OPENING:
        case ZFCP_ERP_STEP_LUN_CLOSING:
        case ZFCP_ERP_STEP_LUN_OPENING:
                /* NOP */
                break;
        }
        return ZFCP_ERP_FAILED;
}

static enum zfcp_erp_act_result zfcp_erp_port_strategy_close(

        struct zfcp_erp_action *erp_action)
{
        int retval;

        retval = zfcp_fsf_close_port(erp_action);
        if (retval == -ENOMEM)
                return ZFCP_ERP_NOMEM;
        erp_action->step = ZFCP_ERP_STEP_PORT_CLOSING;
        if (retval)
                return ZFCP_ERP_FAILED;
        return ZFCP_ERP_CONTINUES;
}

static enum zfcp_erp_act_result zfcp_erp_port_strategy_open_port(
        struct zfcp_erp_action *erp_action)
{
        int retval;

        retval = zfcp_fsf_open_port(erp_action);
        if (retval == -ENOMEM)
                return ZFCP_ERP_NOMEM;
        erp_action->step = ZFCP_ERP_STEP_PORT_OPENING;
        if (retval)
                return ZFCP_ERP_FAILED;
        return ZFCP_ERP_CONTINUES;
}

static int zfcp_erp_open_ptp_port(struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;
        struct zfcp_port *port = act->port;

        if (port->wwpn != adapter->peer_wwpn) {
                zfcp_erp_set_port_status(port, ZFCP_STATUS_COMMON_ERP_FAILED);
                return ZFCP_ERP_FAILED;
        }
        port->d_id = adapter->peer_d_id;
        return zfcp_erp_port_strategy_open_port(act);
}

static enum zfcp_erp_act_result zfcp_erp_port_strategy_open_common(
        struct zfcp_erp_action *act)
{
        struct zfcp_adapter *adapter = act->adapter;
        struct zfcp_port *port = act->port;
        int p_status = atomic_read(&port->status);

        switch (act->step) {
        case ZFCP_ERP_STEP_UNINITIALIZED:
        case ZFCP_ERP_STEP_PHYS_PORT_CLOSING:
        case ZFCP_ERP_STEP_PORT_CLOSING:
                if (fc_host_port_type(adapter->scsi_host) == FC_PORTTYPE_PTP)
                        return zfcp_erp_open_ptp_port(act);
                if (!port->d_id) {
                        zfcp_fc_trigger_did_lookup(port);
                        return ZFCP_ERP_EXIT;
                }
                return zfcp_erp_port_strategy_open_port(act);

        case ZFCP_ERP_STEP_PORT_OPENING:
                /* D_ID might have changed during open */
                if (p_status & ZFCP_STATUS_COMMON_OPEN) {
                        if (!port->d_id) {
                                zfcp_fc_trigger_did_lookup(port);
                                return ZFCP_ERP_EXIT;
                        }
                        return ZFCP_ERP_SUCCEEDED;
                }
                if (port->d_id && !(p_status & ZFCP_STATUS_COMMON_NOESC)) {
                        port->d_id = 0;
                        return ZFCP_ERP_FAILED;
                }
                /* no early return otherwise, continue after switch case */
                break;
        case ZFCP_ERP_STEP_LUN_CLOSING:
        case ZFCP_ERP_STEP_LUN_OPENING:
                /* NOP */
                break;
        }
        return ZFCP_ERP_FAILED;
}

static enum zfcp_erp_act_result zfcp_erp_port_strategy(
        struct zfcp_erp_action *erp_action)
{
        struct zfcp_port *port = erp_action->port;
        int p_status = atomic_read(&port->status);

        if ((p_status & ZFCP_STATUS_COMMON_NOESC) &&
            !(p_status & ZFCP_STATUS_COMMON_OPEN))
                goto close_init_done;

        switch (erp_action->step) {
        case ZFCP_ERP_STEP_UNINITIALIZED:
                if (p_status & ZFCP_STATUS_COMMON_OPEN)
                        return zfcp_erp_port_strategy_close(erp_action);
                break;

        case ZFCP_ERP_STEP_PORT_CLOSING:
                if (p_status & ZFCP_STATUS_COMMON_OPEN)
                        return ZFCP_ERP_FAILED;
                break;
        case ZFCP_ERP_STEP_PHYS_PORT_CLOSING:
        case ZFCP_ERP_STEP_PORT_OPENING:
        case ZFCP_ERP_STEP_LUN_CLOSING:
        case ZFCP_ERP_STEP_LUN_OPENING:
                /* NOP */
                break;
        }

close_init_done:
        if (erp_action->status & ZFCP_STATUS_ERP_CLOSE_ONLY)
                return ZFCP_ERP_EXIT;

        return zfcp_erp_port_strategy_open_common(erp_action);
}

static void zfcp_erp_lun_strategy_clearstati(struct scsi_device *sdev)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        atomic_andnot(ZFCP_STATUS_COMMON_ACCESS_DENIED,
                          &zfcp_sdev->status);
}

static enum zfcp_erp_act_result zfcp_erp_lun_strategy_close(
        struct zfcp_erp_action *erp_action)
{
        int retval = zfcp_fsf_close_lun(erp_action);
        if (retval == -ENOMEM)
                return ZFCP_ERP_NOMEM;
        erp_action->step = ZFCP_ERP_STEP_LUN_CLOSING;
        if (retval)
                return ZFCP_ERP_FAILED;
        return ZFCP_ERP_CONTINUES;
}

static enum zfcp_erp_act_result zfcp_erp_lun_strategy_open(
        struct zfcp_erp_action *erp_action)
{
        int retval = zfcp_fsf_open_lun(erp_action);
        if (retval == -ENOMEM)
                return ZFCP_ERP_NOMEM;
        erp_action->step = ZFCP_ERP_STEP_LUN_OPENING;
        if (retval)
                return  ZFCP_ERP_FAILED;
        return ZFCP_ERP_CONTINUES;
}

static enum zfcp_erp_act_result zfcp_erp_lun_strategy(
        struct zfcp_erp_action *erp_action)
{
        struct scsi_device *sdev = erp_action->sdev;
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        switch (erp_action->step) {
        case ZFCP_ERP_STEP_UNINITIALIZED:
                zfcp_erp_lun_strategy_clearstati(sdev);
                if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
                        return zfcp_erp_lun_strategy_close(erp_action);
                /* already closed */
                fallthrough;
        case ZFCP_ERP_STEP_LUN_CLOSING:
                if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
                        return ZFCP_ERP_FAILED;
                if (erp_action->status & ZFCP_STATUS_ERP_CLOSE_ONLY)
                        return ZFCP_ERP_EXIT;
                return zfcp_erp_lun_strategy_open(erp_action);

        case ZFCP_ERP_STEP_LUN_OPENING:
                if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
                        return ZFCP_ERP_SUCCEEDED;
                break;
        case ZFCP_ERP_STEP_PHYS_PORT_CLOSING:
        case ZFCP_ERP_STEP_PORT_CLOSING:
        case ZFCP_ERP_STEP_PORT_OPENING:
                /* NOP */
                break;
        }
        return ZFCP_ERP_FAILED;
}

static enum zfcp_erp_act_result zfcp_erp_strategy_check_lun(
        struct scsi_device *sdev, enum zfcp_erp_act_result result)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        switch (result) {
        case ZFCP_ERP_SUCCEEDED :
                atomic_set(&zfcp_sdev->erp_counter, 0);
                zfcp_erp_lun_unblock(sdev);
                break;
        case ZFCP_ERP_FAILED :
                atomic_inc(&zfcp_sdev->erp_counter);
                if (atomic_read(&zfcp_sdev->erp_counter) > ZFCP_MAX_ERPS) {
                        dev_err(&zfcp_sdev->port->adapter->ccw_device->dev,
                                "ERP failed for LUN 0x%016Lx on "
                                "port 0x%016Lx\n",
                                (unsigned long long)zfcp_scsi_dev_lun(sdev),
                                (unsigned long long)zfcp_sdev->port->wwpn);
                        zfcp_erp_set_lun_status(sdev,
                                                ZFCP_STATUS_COMMON_ERP_FAILED);
                }
                break;
        case ZFCP_ERP_CONTINUES:
        case ZFCP_ERP_EXIT:
        case ZFCP_ERP_DISMISSED:
        case ZFCP_ERP_NOMEM:
                /* NOP */
                break;
        }

        if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_ERP_FAILED) {
                zfcp_erp_lun_block(sdev, 0);
                result = ZFCP_ERP_EXIT;
        }
        return result;
}

static enum zfcp_erp_act_result zfcp_erp_strategy_check_port(
        struct zfcp_port *port, enum zfcp_erp_act_result result)
{
        switch (result) {
        case ZFCP_ERP_SUCCEEDED :
                atomic_set(&port->erp_counter, 0);
                zfcp_erp_port_unblock(port);
                break;

        case ZFCP_ERP_FAILED :
                if (atomic_read(&port->status) & ZFCP_STATUS_COMMON_NOESC) {
                        zfcp_erp_port_block(port, 0);
                        result = ZFCP_ERP_EXIT;
                }
                atomic_inc(&port->erp_counter);
                if (atomic_read(&port->erp_counter) > ZFCP_MAX_ERPS) {
                        dev_err(&port->adapter->ccw_device->dev,
                                "ERP failed for remote port 0x%016Lx\n",
                                (unsigned long long)port->wwpn);
                        zfcp_erp_set_port_status(port,
                                         ZFCP_STATUS_COMMON_ERP_FAILED);
                }
                break;
        case ZFCP_ERP_CONTINUES:
        case ZFCP_ERP_EXIT:
        case ZFCP_ERP_DISMISSED:
        case ZFCP_ERP_NOMEM:
                /* NOP */
                break;
        }

        if (atomic_read(&port->status) & ZFCP_STATUS_COMMON_ERP_FAILED) {
                zfcp_erp_port_block(port, 0);
                result = ZFCP_ERP_EXIT;
        }
        return result;
}

static enum zfcp_erp_act_result zfcp_erp_strategy_check_adapter(
        struct zfcp_adapter *adapter, enum zfcp_erp_act_result result)
{
        switch (result) {
        case ZFCP_ERP_SUCCEEDED :
                atomic_set(&adapter->erp_counter, 0);
                zfcp_erp_adapter_unblock(adapter);
                break;

        case ZFCP_ERP_FAILED :
                atomic_inc(&adapter->erp_counter);
                if (atomic_read(&adapter->erp_counter) > ZFCP_MAX_ERPS) {
                        dev_err(&adapter->ccw_device->dev,
                                "ERP cannot recover an error "
                                "on the FCP device\n");
                        zfcp_erp_set_adapter_status(adapter,
                                            ZFCP_STATUS_COMMON_ERP_FAILED);
                }
                break;
        case ZFCP_ERP_CONTINUES:
        case ZFCP_ERP_EXIT:
        case ZFCP_ERP_DISMISSED:
        case ZFCP_ERP_NOMEM:
                /* NOP */
                break;
        }

        if (atomic_read(&adapter->status) & ZFCP_STATUS_COMMON_ERP_FAILED) {
                zfcp_erp_adapter_block(adapter, 0);
                result = ZFCP_ERP_EXIT;
        }
        return result;
}

static enum zfcp_erp_act_result zfcp_erp_strategy_check_target(
        struct zfcp_erp_action *erp_action, enum zfcp_erp_act_result result)
{
        struct zfcp_adapter *adapter = erp_action->adapter;
        struct zfcp_port *port = erp_action->port;
        struct scsi_device *sdev = erp_action->sdev;

        switch (erp_action->type) {

        case ZFCP_ERP_ACTION_REOPEN_LUN:
                result = zfcp_erp_strategy_check_lun(sdev, result);
                break;

        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                result = zfcp_erp_strategy_check_port(port, result);
                break;

        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                result = zfcp_erp_strategy_check_adapter(adapter, result);
                break;
        }
        return result;
}

static int zfcp_erp_strat_change_det(atomic_t *target_status, u32 erp_status)
{
        int status = atomic_read(target_status);

        if ((status & ZFCP_STATUS_COMMON_RUNNING) &&
            (erp_status & ZFCP_STATUS_ERP_CLOSE_ONLY))
                return 1; /* take it online */

        if (!(status & ZFCP_STATUS_COMMON_RUNNING) &&
            !(erp_status & ZFCP_STATUS_ERP_CLOSE_ONLY))
                return 1; /* take it offline */

        return 0;
}

static enum zfcp_erp_act_result zfcp_erp_strategy_statechange(
        struct zfcp_erp_action *act, enum zfcp_erp_act_result result)
{
        enum zfcp_erp_act_type type = act->type;
        struct zfcp_adapter *adapter = act->adapter;
        struct zfcp_port *port = act->port;
        struct scsi_device *sdev = act->sdev;
        struct zfcp_scsi_dev *zfcp_sdev;
        u32 erp_status = act->status;

        switch (type) {
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                if (zfcp_erp_strat_change_det(&adapter->status, erp_status)) {
                        _zfcp_erp_adapter_reopen(adapter,
                                                 ZFCP_STATUS_COMMON_ERP_FAILED,
                                                 "ersscg1");
                        return ZFCP_ERP_EXIT;
                }
                break;

        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                if (zfcp_erp_strat_change_det(&port->status, erp_status)) {
                        _zfcp_erp_port_reopen(port,
                                              ZFCP_STATUS_COMMON_ERP_FAILED,
                                              "ersscg2");
                        return ZFCP_ERP_EXIT;
                }
                break;

        case ZFCP_ERP_ACTION_REOPEN_LUN:
                zfcp_sdev = sdev_to_zfcp(sdev);
                if (zfcp_erp_strat_change_det(&zfcp_sdev->status, erp_status)) {
                        _zfcp_erp_lun_reopen(sdev,
                                             ZFCP_STATUS_COMMON_ERP_FAILED,
                                             "ersscg3", 0);
                        return ZFCP_ERP_EXIT;
                }
                break;
        }
        return result;
}

static void zfcp_erp_action_dequeue(struct zfcp_erp_action *erp_action)
{
        struct zfcp_adapter *adapter = erp_action->adapter;
        struct zfcp_scsi_dev *zfcp_sdev;

        adapter->erp_total_count--;
        if (erp_action->status & ZFCP_STATUS_ERP_LOWMEM) {
                adapter->erp_low_mem_count--;
                erp_action->status &= ~ZFCP_STATUS_ERP_LOWMEM;
        }

        list_del(&erp_action->list);
        zfcp_dbf_rec_run("eractd1", erp_action);

        switch (erp_action->type) {
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                zfcp_sdev = sdev_to_zfcp(erp_action->sdev);
                atomic_andnot(ZFCP_STATUS_COMMON_ERP_INUSE,
                                  &zfcp_sdev->status);
                break;

        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                atomic_andnot(ZFCP_STATUS_COMMON_ERP_INUSE,
                                  &erp_action->port->status);
                break;

        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                atomic_andnot(ZFCP_STATUS_COMMON_ERP_INUSE,
                                  &erp_action->adapter->status);
                break;
        }
}

/**
 * zfcp_erp_try_rport_unblock - unblock rport if no more/new recovery
 * @port: zfcp_port whose fc_rport we should try to unblock
 */
static void zfcp_erp_try_rport_unblock(struct zfcp_port *port)
{
        unsigned long flags;
        struct zfcp_adapter *adapter = port->adapter;
        int port_status;
        struct Scsi_Host *shost = adapter->scsi_host;
        struct scsi_device *sdev;

        write_lock_irqsave(&adapter->erp_lock, flags);
        port_status = atomic_read(&port->status);
        if ((port_status & ZFCP_STATUS_COMMON_UNBLOCKED)    == 0 ||
            (port_status & (ZFCP_STATUS_COMMON_ERP_INUSE |
                            ZFCP_STATUS_COMMON_ERP_FAILED)) != 0) {
                /* new ERP of severity >= port triggered elsewhere meanwhile or
                 * local link down (adapter erp_failed but not clear unblock)
                 */
                zfcp_dbf_rec_run_lvl(4, "ertru_p", &port->erp_action);
                write_unlock_irqrestore(&adapter->erp_lock, flags);
                return;
        }
        spin_lock(shost->host_lock);
        __shost_for_each_device(sdev, shost) {
                struct zfcp_scsi_dev *zsdev = sdev_to_zfcp(sdev);
                int lun_status;

                if (sdev->sdev_state == SDEV_DEL ||
                    sdev->sdev_state == SDEV_CANCEL)
                        continue;
                if (zsdev->port != port)
                        continue;
                /* LUN under port of interest */
                lun_status = atomic_read(&zsdev->status);
                if ((lun_status & ZFCP_STATUS_COMMON_ERP_FAILED) != 0)
                        continue; /* unblock rport despite failed LUNs */
                /* LUN recovery not given up yet [maybe follow-up pending] */
                if ((lun_status & ZFCP_STATUS_COMMON_UNBLOCKED) == 0 ||
                    (lun_status & ZFCP_STATUS_COMMON_ERP_INUSE) != 0) {
                        /* LUN blocked:
                         * not yet unblocked [LUN recovery pending]
                         * or meanwhile blocked [new LUN recovery triggered]
                         */
                        zfcp_dbf_rec_run_lvl(4, "ertru_l", &zsdev->erp_action);
                        spin_unlock(shost->host_lock);
                        write_unlock_irqrestore(&adapter->erp_lock, flags);
                        return;
                }
        }
        /* now port has no child or all children have completed recovery,
         * and no ERP of severity >= port was meanwhile triggered elsewhere
         */
        zfcp_scsi_schedule_rport_register(port);
        spin_unlock(shost->host_lock);
        write_unlock_irqrestore(&adapter->erp_lock, flags);
}

static void zfcp_erp_action_cleanup(struct zfcp_erp_action *act,
                                    enum zfcp_erp_act_result result)
{
        struct zfcp_adapter *adapter = act->adapter;
        struct zfcp_port *port = act->port;
        struct scsi_device *sdev = act->sdev;

        switch (act->type) {
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                if (!(act->status & ZFCP_STATUS_ERP_NO_REF))
                        scsi_device_put(sdev);
                zfcp_erp_try_rport_unblock(port);
                break;

        case ZFCP_ERP_ACTION_REOPEN_PORT:
                /* This switch case might also happen after a forced reopen
                 * was successfully done and thus overwritten with a new
                 * non-forced reopen at `ersfs_2'. In this case, we must not
                 * do the clean-up of the non-forced version.
                 */
                if (act->step != ZFCP_ERP_STEP_UNINITIALIZED)
                        if (result == ZFCP_ERP_SUCCEEDED)
                                zfcp_erp_try_rport_unblock(port);
                fallthrough;
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                put_device(&port->dev);
                break;

        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                if (result == ZFCP_ERP_SUCCEEDED) {
                        register_service_level(&adapter->service_level);
                        zfcp_fc_conditional_port_scan(adapter);
                        queue_work(adapter->work_queue, &adapter->ns_up_work);
                } else
                        unregister_service_level(&adapter->service_level);

                kref_put(&adapter->ref, zfcp_adapter_release);
                break;
        }
}

static enum zfcp_erp_act_result zfcp_erp_strategy_do_action(
        struct zfcp_erp_action *erp_action)
{
        switch (erp_action->type) {
        case ZFCP_ERP_ACTION_REOPEN_ADAPTER:
                return zfcp_erp_adapter_strategy(erp_action);
        case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:
                return zfcp_erp_port_forced_strategy(erp_action);
        case ZFCP_ERP_ACTION_REOPEN_PORT:
                return zfcp_erp_port_strategy(erp_action);
        case ZFCP_ERP_ACTION_REOPEN_LUN:
                return zfcp_erp_lun_strategy(erp_action);
        }
        return ZFCP_ERP_FAILED;
}

static enum zfcp_erp_act_result zfcp_erp_strategy(
        struct zfcp_erp_action *erp_action)
{
        enum zfcp_erp_act_result result;
        unsigned long flags;
        struct zfcp_adapter *adapter = erp_action->adapter;

        kref_get(&adapter->ref);

        write_lock_irqsave(&adapter->erp_lock, flags);
        zfcp_erp_strategy_check_fsfreq(erp_action);

        if (erp_action->status & ZFCP_STATUS_ERP_DISMISSED) {
                zfcp_erp_action_dequeue(erp_action);
                result = ZFCP_ERP_DISMISSED;
                goto unlock;
        }

        if (erp_action->status & ZFCP_STATUS_ERP_TIMEDOUT) {
                result = ZFCP_ERP_FAILED;
                goto check_target;
        }

        zfcp_erp_action_to_running(erp_action);

        /* no lock to allow for blocking operations */
        write_unlock_irqrestore(&adapter->erp_lock, flags);
        result = zfcp_erp_strategy_do_action(erp_action);
        write_lock_irqsave(&adapter->erp_lock, flags);

        if (erp_action->status & ZFCP_STATUS_ERP_DISMISSED)
                result = ZFCP_ERP_CONTINUES;

        switch (result) {
        case ZFCP_ERP_NOMEM:
                if (!(erp_action->status & ZFCP_STATUS_ERP_LOWMEM)) {
                        ++adapter->erp_low_mem_count;
                        erp_action->status |= ZFCP_STATUS_ERP_LOWMEM;
                }
                if (adapter->erp_total_count == adapter->erp_low_mem_count)
                        _zfcp_erp_adapter_reopen(adapter, 0, "erstgy1");
                else {
                        zfcp_erp_strategy_memwait(erp_action);
                        result = ZFCP_ERP_CONTINUES;
                }
                goto unlock;

        case ZFCP_ERP_CONTINUES:
                if (erp_action->status & ZFCP_STATUS_ERP_LOWMEM) {
                        --adapter->erp_low_mem_count;
                        erp_action->status &= ~ZFCP_STATUS_ERP_LOWMEM;
                }
                goto unlock;
        case ZFCP_ERP_SUCCEEDED:
        case ZFCP_ERP_FAILED:
        case ZFCP_ERP_EXIT:
        case ZFCP_ERP_DISMISSED:
                /* NOP */
                break;
        }

check_target:
        result = zfcp_erp_strategy_check_target(erp_action, result);
        zfcp_erp_action_dequeue(erp_action);
        result = zfcp_erp_strategy_statechange(erp_action, result);
        if (result == ZFCP_ERP_EXIT)
                goto unlock;
        if (result == ZFCP_ERP_SUCCEEDED)
                zfcp_erp_strategy_followup_success(erp_action);
        if (result == ZFCP_ERP_FAILED)
                zfcp_erp_strategy_followup_failed(erp_action);

 unlock:
        write_unlock_irqrestore(&adapter->erp_lock, flags);

        if (result != ZFCP_ERP_CONTINUES)
                zfcp_erp_action_cleanup(erp_action, result);

        kref_put(&adapter->ref, zfcp_adapter_release);
        return result;
}

static int zfcp_erp_thread(void *data)
{
        struct zfcp_adapter *adapter = (struct zfcp_adapter *) data;
        struct zfcp_erp_action *act;
        unsigned long flags;

        for (;;) {
                wait_event_interruptible(adapter->erp_ready_wq,
                           !list_empty(&adapter->erp_ready_head) ||
                           kthread_should_stop());

                if (kthread_should_stop())
                        break;

                write_lock_irqsave(&adapter->erp_lock, flags);
                act = list_first_entry_or_null(&adapter->erp_ready_head,
                                               struct zfcp_erp_action, list);
                write_unlock_irqrestore(&adapter->erp_lock, flags);

                if (act) {
                        /* there is more to come after dismission, no notify */
                        if (zfcp_erp_strategy(act) != ZFCP_ERP_DISMISSED)
                                zfcp_erp_wakeup(adapter);
                }
        }

        return 0;
}

/**
 * zfcp_erp_thread_setup - Start ERP thread for adapter
 * @adapter: Adapter to start the ERP thread for
 *
 * Return: 0 on success, or error code from kthread_run().
 */
int zfcp_erp_thread_setup(struct zfcp_adapter *adapter)
{
        struct task_struct *thread;

        thread = kthread_run(zfcp_erp_thread, adapter, "zfcperp%s",
                             dev_name(&adapter->ccw_device->dev));
        if (IS_ERR(thread)) {
                dev_err(&adapter->ccw_device->dev,
                        "Creating an ERP thread for the FCP device failed.\n");
                return PTR_ERR(thread);
        }

        adapter->erp_thread = thread;
        return 0;
}

/**
 * zfcp_erp_thread_kill - Stop ERP thread.
 * @adapter: Adapter where the ERP thread should be stopped.
 *
 * The caller of this routine ensures that the specified adapter has
 * been shut down and that this operation has been completed. Thus,
 * there are no pending erp_actions which would need to be handled
 * here.
 */
void zfcp_erp_thread_kill(struct zfcp_adapter *adapter)
{
        kthread_stop(adapter->erp_thread);
        adapter->erp_thread = NULL;
        WARN_ON(!list_empty(&adapter->erp_ready_head));
        WARN_ON(!list_empty(&adapter->erp_running_head));
}

/**
 * zfcp_erp_wait - wait for completion of error recovery on an adapter
 * @adapter: adapter for which to wait for completion of its error recovery
 */
void zfcp_erp_wait(struct zfcp_adapter *adapter)
{
        wait_event(adapter->erp_done_wqh,
                   !(atomic_read(&adapter->status) &
                        ZFCP_STATUS_ADAPTER_ERP_PENDING));
}

/**
 * zfcp_erp_set_adapter_status - set adapter status bits
 * @adapter: adapter to change the status
 * @mask: status bits to change
 *
 * Changes in common status bits are propagated to attached ports and LUNs.
 */
void zfcp_erp_set_adapter_status(struct zfcp_adapter *adapter, u32 mask)
{
        struct zfcp_port *port;
        struct scsi_device *sdev;
        unsigned long flags;
        u32 common_mask = mask & ZFCP_COMMON_FLAGS;

        atomic_or(mask, &adapter->status);

        if (!common_mask)
                return;

        read_lock_irqsave(&adapter->port_list_lock, flags);
        list_for_each_entry(port, &adapter->port_list, list)
                atomic_or(common_mask, &port->status);
        read_unlock_irqrestore(&adapter->port_list_lock, flags);

        /*
         * if `scsi_host` is missing, xconfig/xport data has never completed
         * yet, so we can't access it, but there are also no SDEVs yet
         */
        if (adapter->scsi_host == NULL)
                return;

        spin_lock_irqsave(adapter->scsi_host->host_lock, flags);
        __shost_for_each_device(sdev, adapter->scsi_host)
                atomic_or(common_mask, &sdev_to_zfcp(sdev)->status);
        spin_unlock_irqrestore(adapter->scsi_host->host_lock, flags);
}

/**
 * zfcp_erp_clear_adapter_status - clear adapter status bits
 * @adapter: adapter to change the status
 * @mask: status bits to change
 *
 * Changes in common status bits are propagated to attached ports and LUNs.
 */
void zfcp_erp_clear_adapter_status(struct zfcp_adapter *adapter, u32 mask)
{
        struct zfcp_port *port;
        struct scsi_device *sdev;
        unsigned long flags;
        u32 common_mask = mask & ZFCP_COMMON_FLAGS;
        u32 clear_counter = mask & ZFCP_STATUS_COMMON_ERP_FAILED;

        atomic_andnot(mask, &adapter->status);

        if (!common_mask)
                return;

        if (clear_counter)
                atomic_set(&adapter->erp_counter, 0);

        read_lock_irqsave(&adapter->port_list_lock, flags);
        list_for_each_entry(port, &adapter->port_list, list) {
                atomic_andnot(common_mask, &port->status);
                if (clear_counter)
                        atomic_set(&port->erp_counter, 0);
        }
        read_unlock_irqrestore(&adapter->port_list_lock, flags);

        /*
         * if `scsi_host` is missing, xconfig/xport data has never completed
         * yet, so we can't access it, but there are also no SDEVs yet
         */
        if (adapter->scsi_host == NULL)
                return;

        spin_lock_irqsave(adapter->scsi_host->host_lock, flags);
        __shost_for_each_device(sdev, adapter->scsi_host) {
                atomic_andnot(common_mask, &sdev_to_zfcp(sdev)->status);
                if (clear_counter)
                        atomic_set(&sdev_to_zfcp(sdev)->erp_counter, 0);
        }
        spin_unlock_irqrestore(adapter->scsi_host->host_lock, flags);
}

/**
 * zfcp_erp_set_port_status - set port status bits
 * @port: port to change the status
 * @mask: status bits to change
 *
 * Changes in common status bits are propagated to attached LUNs.
 */
void zfcp_erp_set_port_status(struct zfcp_port *port, u32 mask)
{
        struct scsi_device *sdev;
        u32 common_mask = mask & ZFCP_COMMON_FLAGS;
        unsigned long flags;

        atomic_or(mask, &port->status);

        if (!common_mask)
                return;

        spin_lock_irqsave(port->adapter->scsi_host->host_lock, flags);
        __shost_for_each_device(sdev, port->adapter->scsi_host)
                if (sdev_to_zfcp(sdev)->port == port)
                        atomic_or(common_mask,
                                        &sdev_to_zfcp(sdev)->status);
        spin_unlock_irqrestore(port->adapter->scsi_host->host_lock, flags);
}

/**
 * zfcp_erp_clear_port_status - clear port status bits
 * @port: adapter to change the status
 * @mask: status bits to change
 *
 * Changes in common status bits are propagated to attached LUNs.
 */
void zfcp_erp_clear_port_status(struct zfcp_port *port, u32 mask)
{
        struct scsi_device *sdev;
        u32 common_mask = mask & ZFCP_COMMON_FLAGS;
        u32 clear_counter = mask & ZFCP_STATUS_COMMON_ERP_FAILED;
        unsigned long flags;

        atomic_andnot(mask, &port->status);

        if (!common_mask)
                return;

        if (clear_counter)
                atomic_set(&port->erp_counter, 0);

        spin_lock_irqsave(port->adapter->scsi_host->host_lock, flags);
        __shost_for_each_device(sdev, port->adapter->scsi_host)
                if (sdev_to_zfcp(sdev)->port == port) {
                        atomic_andnot(common_mask,
                                          &sdev_to_zfcp(sdev)->status);
                        if (clear_counter)
                                atomic_set(&sdev_to_zfcp(sdev)->erp_counter, 0);
                }
        spin_unlock_irqrestore(port->adapter->scsi_host->host_lock, flags);
}

/**
 * zfcp_erp_set_lun_status - set lun status bits
 * @sdev: SCSI device / lun to set the status bits
 * @mask: status bits to change
 */
void zfcp_erp_set_lun_status(struct scsi_device *sdev, u32 mask)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        atomic_or(mask, &zfcp_sdev->status);
}

/**
 * zfcp_erp_clear_lun_status - clear lun status bits
 * @sdev: SCSi device / lun to clear the status bits
 * @mask: status bits to change
 */
void zfcp_erp_clear_lun_status(struct scsi_device *sdev, u32 mask)
{
        struct zfcp_scsi_dev *zfcp_sdev = sdev_to_zfcp(sdev);

        atomic_andnot(mask, &zfcp_sdev->status);

        if (mask & ZFCP_STATUS_COMMON_ERP_FAILED)
                atomic_set(&zfcp_sdev->erp_counter, 0);
}

/**
 * zfcp_erp_adapter_reset_sync() - Really reopen adapter and wait.
 * @adapter: Pointer to zfcp_adapter to reopen.
 * @dbftag: Trace tag string of length %ZFCP_DBF_TAG_LEN.
 */
void zfcp_erp_adapter_reset_sync(struct zfcp_adapter *adapter, char *dbftag)
{
        zfcp_erp_set_adapter_status(adapter, ZFCP_STATUS_COMMON_RUNNING);
        zfcp_erp_adapter_reopen(adapter, ZFCP_STATUS_COMMON_ERP_FAILED, dbftag);
        zfcp_erp_wait(adapter);
}