Quelle  hosts.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  hosts.c Copyright (C) 1992 Drew Eckhardt
 *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
 *          Copyright (C) 2002-2003 Christoph Hellwig
 *
 *  mid to lowlevel SCSI driver interface
 *      Initial versions: Drew Eckhardt
 *      Subsequent revisions: Eric Youngdale
 *
 *  <drew@colorado.edu>
 *
 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
 *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
 *     August 4, 1999 Fred Lewis, Intel DuPont
 *
 *  Updated to reflect the new initialization scheme for the higher 
 *  level of scsi drivers (sd/sr/st)
 *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
 *
 *  Restructured scsi_host lists and associated functions.
 *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
 */

#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/transport_class.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/idr.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_cmnd.h>

#include "scsi_priv.h"
#include "scsi_logging.h"


static int shost_eh_deadline = -1;

module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(eh_deadline,
   "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");

static DEFINE_IDA(host_index_ida);


static void scsi_host_cls_release(struct device *dev)
{
 put_device(&class_to_shost(dev)->shost_gendev);
}

static struct class shost_class = {
 .name  = "scsi_host",
 .dev_release = scsi_host_cls_release,
 .dev_groups = scsi_shost_groups,
};

/**
 * scsi_host_set_state - Take the given host through the host state model.
 * @shost: scsi host to change the state of.
 * @state: state to change to.
 *
 * Returns zero if unsuccessful or an error if the requested
 * transition is illegal.
 **/
int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
{
 enum scsi_host_state oldstate = shost->shost_state;

 if (state == oldstate)
  return 0;

 switch (state) {
 case SHOST_CREATED:
  /* There are no legal states that come back to
 * created.  This is the manually initialised start
 * state */
  goto illegal;

 case SHOST_RUNNING:
  switch (oldstate) {
  case SHOST_CREATED:
  case SHOST_RECOVERY:
   break;
  default:
   goto illegal;
  }
  break;

 case SHOST_RECOVERY:
  switch (oldstate) {
  case SHOST_RUNNING:
   break;
  default:
   goto illegal;
  }
  break;

 case SHOST_CANCEL:
  switch (oldstate) {
  case SHOST_CREATED:
  case SHOST_RUNNING:
  case SHOST_CANCEL_RECOVERY:
   break;
  default:
   goto illegal;
  }
  break;

 case SHOST_DEL:
  switch (oldstate) {
  case SHOST_CANCEL:
  case SHOST_DEL_RECOVERY:
   break;
  default:
   goto illegal;
  }
  break;

 case SHOST_CANCEL_RECOVERY:
  switch (oldstate) {
  case SHOST_CANCEL:
  case SHOST_RECOVERY:
   break;
  default:
   goto illegal;
  }
  break;

 case SHOST_DEL_RECOVERY:
  switch (oldstate) {
  case SHOST_CANCEL_RECOVERY:
   break;
  default:
   goto illegal;
  }
  break;
 }
 shost->shost_state = state;
 return 0;

 illegal:
 SCSI_LOG_ERROR_RECOVERY(1,
    shost_printk(KERN_ERR, shost,
          "Illegal host state transition"
          "%s->%s\n",
          scsi_host_state_name(oldstate),
          scsi_host_state_name(state)));
 return -EINVAL;
}

/**
 * scsi_remove_host - remove a scsi host
 * @shost: a pointer to a scsi host to remove
 **/
void scsi_remove_host(struct Scsi_Host *shost)
{
 unsigned long flags;

 mutex_lock(&shost->scan_mutex);
 spin_lock_irqsave(shost->host_lock, flags);
 if (scsi_host_set_state(shost, SHOST_CANCEL))
  if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
   spin_unlock_irqrestore(shost->host_lock, flags);
   mutex_unlock(&shost->scan_mutex);
   return;
  }
 spin_unlock_irqrestore(shost->host_lock, flags);

 scsi_autopm_get_host(shost);
 flush_workqueue(shost->tmf_work_q);
 scsi_forget_host(shost);
 mutex_unlock(&shost->scan_mutex);
 scsi_proc_host_rm(shost);
 scsi_proc_hostdir_rm(shost->hostt);

 /*
 * New SCSI devices cannot be attached anymore because of the SCSI host
 * state so drop the tag set refcnt. Wait until the tag set refcnt drops
 * to zero because .exit_cmd_priv implementations may need the host
 * pointer.
 */
 kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
 wait_for_completion(&shost->tagset_freed);

 spin_lock_irqsave(shost->host_lock, flags);
 if (scsi_host_set_state(shost, SHOST_DEL))
  BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
 spin_unlock_irqrestore(shost->host_lock, flags);

 transport_unregister_device(&shost->shost_gendev);
 device_unregister(&shost->shost_dev);
 device_del(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_remove_host);

/**
 * scsi_add_host_with_dma - add a scsi host with dma device
 * @shost: scsi host pointer to add
 * @dev: a struct device of type scsi class
 * @dma_dev: dma device for the host
 *
 * Note: You rarely need to worry about this unless you're in a
 * virtualised host environments, so use the simpler scsi_add_host()
 * function instead.
 *
 * Return value: 
 *  0 on success / != 0 for error
 **/
int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
      struct device *dma_dev)
{
 const struct scsi_host_template *sht = shost->hostt;
 int error = -EINVAL;

 shost_printk(KERN_INFO, shost, "%s\n",
   sht->info ? sht->info(shost) : sht->name);

 if (!shost->can_queue) {
  shost_printk(KERN_ERR, shost,
        "can_queue = 0 no longer supported\n");
  goto fail;
 }

 /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
 shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
       shost->can_queue);

 error = scsi_init_sense_cache(shost);
 if (error)
  goto fail;

 if (!shost->shost_gendev.parent)
  shost->shost_gendev.parent = dev ? dev : &platform_bus;
 if (!dma_dev)
  dma_dev = shost->shost_gendev.parent;

 shost->dma_dev = dma_dev;

 if (dma_dev->dma_mask) {
  shost->max_sectors = min_t(unsigned int, shost->max_sectors,
    dma_max_mapping_size(dma_dev) >> SECTOR_SHIFT);
 }

 error = scsi_mq_setup_tags(shost);
 if (error)
  goto fail;

 kref_init(&shost->tagset_refcnt);
 init_completion(&shost->tagset_freed);

 /*
 * Increase usage count temporarily here so that calling
 * scsi_autopm_put_host() will trigger runtime idle if there is
 * nothing else preventing suspending the device.
 */
 pm_runtime_get_noresume(&shost->shost_gendev);
 pm_runtime_set_active(&shost->shost_gendev);
 pm_runtime_enable(&shost->shost_gendev);
 device_enable_async_suspend(&shost->shost_gendev);

 error = device_add(&shost->shost_gendev);
 if (error)
  goto out_disable_runtime_pm;

 scsi_host_set_state(shost, SHOST_RUNNING);
 get_device(shost->shost_gendev.parent);

 device_enable_async_suspend(&shost->shost_dev);

 get_device(&shost->shost_gendev);
 error = device_add(&shost->shost_dev);
 if (error)
  goto out_del_gendev;

 if (shost->transportt->host_size) {
  shost->shost_data = kzalloc(shost->transportt->host_size,
      GFP_KERNEL);
  if (shost->shost_data == NULL) {
   error = -ENOMEM;
   goto out_del_dev;
  }
 }

 if (shost->transportt->create_work_queue) {
  shost->work_q = alloc_workqueue(
   "scsi_wq_%d",
   WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND, 1,
   shost->host_no);

  if (!shost->work_q) {
   error = -EINVAL;
   goto out_del_dev;
  }
 }

 error = scsi_sysfs_add_host(shost);
 if (error)
  goto out_del_dev;

 scsi_proc_host_add(shost);
 scsi_autopm_put_host(shost);
 return error;

 /*
 * Any host allocation in this function will be freed in
 * scsi_host_dev_release().
 */
 out_del_dev:
 device_del(&shost->shost_dev);
 out_del_gendev:
 /*
 * Host state is SHOST_RUNNING so we have to explicitly release
 * ->shost_dev.
 */
 put_device(&shost->shost_dev);
 device_del(&shost->shost_gendev);
 out_disable_runtime_pm:
 device_disable_async_suspend(&shost->shost_gendev);
 pm_runtime_disable(&shost->shost_gendev);
 pm_runtime_set_suspended(&shost->shost_gendev);
 pm_runtime_put_noidle(&shost->shost_gendev);
 kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
 fail:
 return error;
}
EXPORT_SYMBOL(scsi_add_host_with_dma);

static void scsi_host_dev_release(struct device *dev)
{
 struct Scsi_Host *shost = dev_to_shost(dev);
 struct device *parent = dev->parent;

 /* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
 rcu_barrier();

 if (shost->tmf_work_q)
  destroy_workqueue(shost->tmf_work_q);
 if (shost->ehandler)
  kthread_stop(shost->ehandler);
 if (shost->work_q)
  destroy_workqueue(shost->work_q);

 if (shost->shost_state == SHOST_CREATED) {
  /*
 * Free the shost_dev device name and remove the proc host dir
 * here if scsi_host_{alloc,put}() have been called but neither
 * scsi_host_add() nor scsi_remove_host() has been called.
 * This avoids that the memory allocated for the shost_dev
 * name as well as the proc dir structure are leaked.
 */
  scsi_proc_hostdir_rm(shost->hostt);
  kfree(dev_name(&shost->shost_dev));
 }

 kfree(shost->shost_data);

 ida_free(&host_index_ida, shost->host_no);

 if (shost->shost_state != SHOST_CREATED)
  put_device(parent);
 kfree(shost);
}

static const struct device_type scsi_host_type = {
 .name =  "scsi_host",
 .release = scsi_host_dev_release,
};

/**
 * scsi_host_alloc - register a scsi host adapter instance.
 * @sht: pointer to scsi host template
 * @privsize: extra bytes to allocate for driver
 *
 * Note:
 *  Allocate a new Scsi_Host and perform basic initialization.
 *  The host is not published to the scsi midlayer until scsi_add_host
 *  is called.
 *
 * Return value:
 *  Pointer to a new Scsi_Host
 **/
struct Scsi_Host *scsi_host_alloc(const struct scsi_host_template *sht, int privsize)
{
 struct Scsi_Host *shost;
 int index;

 shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
 if (!shost)
  return NULL;

 shost->host_lock = &shost->default_lock;
 spin_lock_init(shost->host_lock);
 shost->shost_state = SHOST_CREATED;
 INIT_LIST_HEAD(&shost->__devices);
 INIT_LIST_HEAD(&shost->__targets);
 INIT_LIST_HEAD(&shost->eh_abort_list);
 INIT_LIST_HEAD(&shost->eh_cmd_q);
 INIT_LIST_HEAD(&shost->starved_list);
 init_waitqueue_head(&shost->host_wait);
 mutex_init(&shost->scan_mutex);

 index = ida_alloc(&host_index_ida, GFP_KERNEL);
 if (index < 0) {
  kfree(shost);
  return NULL;
 }
 shost->host_no = index;

 shost->dma_channel = 0xff;

 /* These three are default values which can be overridden */
 shost->max_channel = 0;
 shost->max_id = 8;
 shost->max_lun = 8;

 /* Give each shost a default transportt */
 shost->transportt = &blank_transport_template;

 /*
 * All drivers right now should be able to handle 12 byte
 * commands.  Every so often there are requests for 16 byte
 * commands, but individual low-level drivers need to certify that
 * they actually do something sensible with such commands.
 */
 shost->max_cmd_len = 12;
 shost->hostt = sht;
 shost->this_id = sht->this_id;
 shost->can_queue = sht->can_queue;
 shost->sg_tablesize = sht->sg_tablesize;
 shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 shost->cmd_per_lun = sht->cmd_per_lun;
 shost->no_write_same = sht->no_write_same;
 shost->host_tagset = sht->host_tagset;
 shost->queuecommand_may_block = sht->queuecommand_may_block;

 if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
  shost->eh_deadline = -1;
 else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
  shost_printk(KERN_WARNING, shost,
        "eh_deadline %u too large, setting to %u\n",
        shost_eh_deadline, INT_MAX / HZ);
  shost->eh_deadline = INT_MAX;
 } else
  shost->eh_deadline = shost_eh_deadline * HZ;

 if (sht->supported_mode == MODE_UNKNOWN)
  /* means we didn't set it ... default to INITIATOR */
  shost->active_mode = MODE_INITIATOR;
 else
  shost->active_mode = sht->supported_mode;

 if (sht->max_host_blocked)
  shost->max_host_blocked = sht->max_host_blocked;
 else
  shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;

 /*
 * If the driver imposes no hard sector transfer limit, start at
 * machine infinity initially.
 */
 if (sht->max_sectors)
  shost->max_sectors = sht->max_sectors;
 else
  shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;

 shost->virt_boundary_mask = sht->virt_boundary_mask;
 if (shost->virt_boundary_mask) {
  WARN_ON_ONCE(sht->max_segment_size &&
        sht->max_segment_size != UINT_MAX);
  shost->max_segment_size = UINT_MAX;
 } else {
  if (sht->max_segment_size)
   shost->max_segment_size = sht->max_segment_size;
  else
   shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
 }

 /* 32-byte (dword) is a common minimum for HBAs. */
 if (sht->dma_alignment)
  shost->dma_alignment = sht->dma_alignment;
 else
  shost->dma_alignment = 3;

 /*
 * assume a 4GB boundary, if not set
 */
 if (sht->dma_boundary)
  shost->dma_boundary = sht->dma_boundary;
 else
  shost->dma_boundary = 0xffffffff;

 device_initialize(&shost->shost_gendev);
 dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 shost->shost_gendev.bus = &scsi_bus_type;
 shost->shost_gendev.type = &scsi_host_type;
 scsi_enable_async_suspend(&shost->shost_gendev);

 device_initialize(&shost->shost_dev);
 shost->shost_dev.parent = &shost->shost_gendev;
 shost->shost_dev.class = &shost_class;
 dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
 shost->shost_dev.groups = sht->shost_groups;

 shost->ehandler = kthread_run(scsi_error_handler, shost,
   "scsi_eh_%d", shost->host_no);
 if (IS_ERR(shost->ehandler)) {
  shost_printk(KERN_WARNING, shost,
   "error handler thread failed to spawn, error = %ld\n",
   PTR_ERR(shost->ehandler));
  shost->ehandler = NULL;
  goto fail;
 }

 shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
     WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
        1, shost->host_no);
 if (!shost->tmf_work_q) {
  shost_printk(KERN_WARNING, shost,
        "failed to create tmf workq\n");
  goto fail;
 }
 if (scsi_proc_hostdir_add(shost->hostt) < 0)
  goto fail;
 return shost;
 fail:
 /*
 * Host state is still SHOST_CREATED and that is enough to release
 * ->shost_gendev. scsi_host_dev_release() will free
 * dev_name(&shost->shost_dev).
 */
 put_device(&shost->shost_gendev);

 return NULL;
}
EXPORT_SYMBOL(scsi_host_alloc);

static int __scsi_host_match(struct device *dev, const void *data)
{
 struct Scsi_Host *p;
 const unsigned int *hostnum = data;

 p = class_to_shost(dev);
 return p->host_no == *hostnum;
}

/**
 * scsi_host_lookup - get a reference to a Scsi_Host by host no
 * @hostnum: host number to locate
 *
 * Return value:
 * A pointer to located Scsi_Host or NULL.
 *
 * The caller must do a scsi_host_put() to drop the reference
 * that scsi_host_get() took. The put_device() below dropped
 * the reference from class_find_device().
 **/
struct Scsi_Host *scsi_host_lookup(unsigned int hostnum)
{
 struct device *cdev;
 struct Scsi_Host *shost = NULL;

 cdev = class_find_device(&shost_class, NULL, &hostnum,
     __scsi_host_match);
 if (cdev) {
  shost = scsi_host_get(class_to_shost(cdev));
  put_device(cdev);
 }
 return shost;
}
EXPORT_SYMBOL(scsi_host_lookup);

/**
 * scsi_host_get - inc a Scsi_Host ref count
 * @shost: Pointer to Scsi_Host to inc.
 **/
struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
{
 if ((shost->shost_state == SHOST_DEL) ||
  !get_device(&shost->shost_gendev))
  return NULL;
 return shost;
}
EXPORT_SYMBOL(scsi_host_get);

static bool scsi_host_check_in_flight(struct request *rq, void *data)
{
 int *count = data;
 struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);

 if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
  (*count)++;

 return true;
}

/**
 * scsi_host_busy - Return the host busy counter
 * @shost: Pointer to Scsi_Host to inc.
 **/
int scsi_host_busy(struct Scsi_Host *shost)
{
 int cnt = 0;

 blk_mq_tagset_busy_iter(&shost->tag_set,
    scsi_host_check_in_flight, &cnt);
 return cnt;
}
EXPORT_SYMBOL(scsi_host_busy);

/**
 * scsi_host_put - dec a Scsi_Host ref count
 * @shost: Pointer to Scsi_Host to dec.
 **/
void scsi_host_put(struct Scsi_Host *shost)
{
 put_device(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_host_put);

int scsi_init_hosts(void)
{
 return class_register(&shost_class);
}

void scsi_exit_hosts(void)
{
 class_unregister(&shost_class);
 ida_destroy(&host_index_ida);
}

int scsi_is_host_device(const struct device *dev)
{
 return dev->type == &scsi_host_type;
}
EXPORT_SYMBOL(scsi_is_host_device);

/**
 * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 * @shost: Pointer to Scsi_Host.
 * @work: Work to queue for execution.
 *
 * Return value:
 *  1 - work queued for execution
 * 0 - work is already queued
 * -EINVAL - work queue doesn't exist
 **/
int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
{
 if (unlikely(!shost->work_q)) {
  shost_printk(KERN_ERR, shost,
   "ERROR: Scsi host '%s' attempted to queue scsi-work, "
   "when no workqueue created.\n", shost->hostt->name);
  dump_stack();

  return -EINVAL;
 }

 return queue_work(shost->work_q, work);
}
EXPORT_SYMBOL_GPL(scsi_queue_work);

/**
 * scsi_flush_work - Flush a Scsi_Host's workqueue.
 * @shost: Pointer to Scsi_Host.
 **/
void scsi_flush_work(struct Scsi_Host *shost)
{
 if (!shost->work_q) {
  shost_printk(KERN_ERR, shost,
   "ERROR: Scsi host '%s' attempted to flush scsi-work, "
   "when no workqueue created.\n", shost->hostt->name);
  dump_stack();
  return;
 }

 flush_workqueue(shost->work_q);
}
EXPORT_SYMBOL_GPL(scsi_flush_work);

static bool complete_all_cmds_iter(struct request *rq, void *data)
{
 struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 enum scsi_host_status status = *(enum scsi_host_status *)data;

 scsi_dma_unmap(scmd);
 scmd->result = 0;
 set_host_byte(scmd, status);
 scsi_done(scmd);
 return true;
}

/**
 * scsi_host_complete_all_commands - Terminate all running commands
 * @shost: Scsi Host on which commands should be terminated
 * @status: Status to be set for the terminated commands
 *
 * There is no protection against modification of the number
 * of outstanding commands. It is the responsibility of the
 * caller to ensure that concurrent I/O submission and/or
 * completion is stopped when calling this function.
 */
void scsi_host_complete_all_commands(struct Scsi_Host *shost,
         enum scsi_host_status status)
{
 blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
    &status);
}
EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);

struct scsi_host_busy_iter_data {
 bool (*fn)(struct scsi_cmnd *, void *);
 void *priv;
};

static bool __scsi_host_busy_iter_fn(struct request *req, void *priv)
{
 struct scsi_host_busy_iter_data *iter_data = priv;
 struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);

 return iter_data->fn(sc, iter_data->priv);
}

/**
 * scsi_host_busy_iter - Iterate over all busy commands
 * @shost: Pointer to Scsi_Host.
 * @fn: Function to call on each busy command
 * @priv: Data pointer passed to @fn
 *
 * If locking against concurrent command completions is required
 * ithas to be provided by the caller
 **/
void scsi_host_busy_iter(struct Scsi_Host *shost,
    bool (*fn)(struct scsi_cmnd *, void *),
    void *priv)
{
 struct scsi_host_busy_iter_data iter_data = {
  .fn = fn,
  .priv = priv,
 };

 blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
    &iter_data);
}
EXPORT_SYMBOL_GPL(scsi_host_busy_iter);