scsi: allocate scsi_cmnd structures as part of struct request

Rely on the new block layer functionality to allocate additional driver
specific data behind struct request instead of implementing it in SCSI
itѕelf.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/scsi/hosts.c

@@ -230,19 +230,6 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 		}
 	}
 
-	/*
-	 * Note that we allocate the freelist even for the MQ case for now,
-	 * as we need a command set aside for scsi_reset_provider.  Having
-	 * the full host freelist and one command available for that is a
-	 * little heavy-handed, but avoids introducing a special allocator
-	 * just for this.  Eventually the structure of scsi_reset_provider
-	 * will need a major overhaul.
-	 */
-	error = scsi_setup_command_freelist(shost);
-	if (error)
-		goto out_destroy_tags;
-
-
 	if (!shost->shost_gendev.parent)
 		shost->shost_gendev.parent = dev ? dev : &platform_bus;
 	if (!dma_dev)
@@ -262,7 +249,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 
 	error = device_add(&shost->shost_gendev);
 	if (error)
-		goto out_destroy_freelist;
+		goto out_disable_runtime_pm;
 
 	scsi_host_set_state(shost, SHOST_RUNNING);
 	get_device(shost->shost_gendev.parent);
@@ -312,13 +299,11 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 	device_del(&shost->shost_dev);
  out_del_gendev:
 	device_del(&shost->shost_gendev);
- out_destroy_freelist:
+ 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);
-	scsi_destroy_command_freelist(shost);
- out_destroy_tags:
 	if (shost_use_blk_mq(shost))
 		scsi_mq_destroy_tags(shost);
  fail:
@@ -359,7 +344,6 @@ static void scsi_host_dev_release(struct device *dev)
 		kfree(dev_name(&shost->shost_dev));
 	}
 
-	scsi_destroy_command_freelist(shost);
 	if (shost_use_blk_mq(shost)) {
 		if (shost->tag_set.tags)
 			scsi_mq_destroy_tags(shost);

drivers/scsi/scsi.c

@@ -98,163 +98,6 @@ EXPORT_SYMBOL(scsi_sd_probe_domain);
 ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain);
 EXPORT_SYMBOL(scsi_sd_pm_domain);
 
-struct scsi_host_cmd_pool {
-	struct kmem_cache	*cmd_slab;
-	unsigned int		users;
-	char			*cmd_name;
-};
-
-static struct scsi_host_cmd_pool scsi_cmd_pool = {
-	.cmd_name	= "scsi_cmd_cache",
-};
-
-static DEFINE_MUTEX(host_cmd_pool_mutex);
-
-/**
- * scsi_host_free_command - internal function to release a command
- * @shost:	host to free the command for
- * @cmd:	command to release
- *
- * the command must previously have been allocated by
- * scsi_host_alloc_command.
- */
-static void
-scsi_host_free_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
-{
-	struct scsi_host_cmd_pool *pool = shost->cmd_pool;
-
-	if (cmd->prot_sdb)
-		kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
-	scsi_free_sense_buffer(shost, cmd->sense_buffer);
-	kmem_cache_free(pool->cmd_slab, cmd);
-}
-
-/**
- * scsi_host_alloc_command - internal function to allocate command
- * @shost:	SCSI host whose pool to allocate from
- * @gfp_mask:	mask for the allocation
- *
- * Returns a fully allocated command with sense buffer and protection
- * data buffer (where applicable) or NULL on failure
- */
-static struct scsi_cmnd *
-scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
-{
-	struct scsi_host_cmd_pool *pool = shost->cmd_pool;
-	struct scsi_cmnd *cmd;
-
-	cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask);
-	if (!cmd)
-		goto fail;
-
-	cmd->sense_buffer = scsi_alloc_sense_buffer(shost, gfp_mask,
-			NUMA_NO_NODE);
-	if (!cmd->sense_buffer)
-		goto fail_free_cmd;
-
-	if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
-		cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
-		if (!cmd->prot_sdb)
-			goto fail_free_sense;
-	}
-
-	return cmd;
-
-fail_free_sense:
-	scsi_free_sense_buffer(shost, cmd->sense_buffer);
-fail_free_cmd:
-	kmem_cache_free(pool->cmd_slab, cmd);
-fail:
-	return NULL;
-}
-
-/**
- * __scsi_get_command - Allocate a struct scsi_cmnd
- * @shost: host to transmit command
- * @gfp_mask: allocation mask
- *
- * Description: allocate a struct scsi_cmd from host's slab, recycling from the
- *              host's free_list if necessary.
- */
-static struct scsi_cmnd *
-__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
-{
-	struct scsi_cmnd *cmd = scsi_host_alloc_command(shost, gfp_mask);
-
-	if (unlikely(!cmd)) {
-		unsigned long flags;
-
-		spin_lock_irqsave(&shost->free_list_lock, flags);
-		if (likely(!list_empty(&shost->free_list))) {
-			cmd = list_entry(shost->free_list.next,
-					 struct scsi_cmnd, list);
-			list_del_init(&cmd->list);
-		}
-		spin_unlock_irqrestore(&shost->free_list_lock, flags);
-
-		if (cmd) {
-			void *buf, *prot;
-
-			buf = cmd->sense_buffer;
-			prot = cmd->prot_sdb;
-
-			memset(cmd, 0, sizeof(*cmd));
-
-			cmd->sense_buffer = buf;
-			cmd->prot_sdb = prot;
-		}
-	}
-
-	return cmd;
-}
-
-/**
- * scsi_get_command - Allocate and setup a scsi command block
- * @dev: parent scsi device
- * @gfp_mask: allocator flags
- *
- * Returns:	The allocated scsi command structure.
- */
-struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
-{
-	struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);
-	unsigned long flags;
-
-	if (unlikely(cmd == NULL))
-		return NULL;
-
-	cmd->device = dev;
-	INIT_LIST_HEAD(&cmd->list);
-	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
-	spin_lock_irqsave(&dev->list_lock, flags);
-	list_add_tail(&cmd->list, &dev->cmd_list);
-	spin_unlock_irqrestore(&dev->list_lock, flags);
-	cmd->jiffies_at_alloc = jiffies;
-	return cmd;
-}
-
-/**
- * __scsi_put_command - Free a struct scsi_cmnd
- * @shost: dev->host
- * @cmd: Command to free
- */
-static void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
-{
-	unsigned long flags;
-
-	if (unlikely(list_empty(&shost->free_list))) {
-		spin_lock_irqsave(&shost->free_list_lock, flags);
-		if (list_empty(&shost->free_list)) {
-			list_add(&cmd->list, &shost->free_list);
-			cmd = NULL;
-		}
-		spin_unlock_irqrestore(&shost->free_list_lock, flags);
-	}
-
-	if (likely(cmd != NULL))
-		scsi_host_free_command(shost, cmd);
-}
-
 /**
  * scsi_put_command - Free a scsi command block
  * @cmd: command block to free
@@ -274,168 +117,6 @@ void scsi_put_command(struct scsi_cmnd *cmd)
 	spin_unlock_irqrestore(&cmd->device->list_lock, flags);
 
 	BUG_ON(delayed_work_pending(&cmd->abort_work));
-
-	__scsi_put_command(cmd->device->host, cmd);
-}
-
-static struct scsi_host_cmd_pool *
-scsi_find_host_cmd_pool(struct Scsi_Host *shost)
-{
-	if (shost->hostt->cmd_size)
-		return shost->hostt->cmd_pool;
-	return &scsi_cmd_pool;
-}
-
-static void
-scsi_free_host_cmd_pool(struct scsi_host_cmd_pool *pool)
-{
-	kfree(pool->cmd_name);
-	kfree(pool);
-}
-
-static struct scsi_host_cmd_pool *
-scsi_alloc_host_cmd_pool(struct Scsi_Host *shost)
-{
-	struct scsi_host_template *hostt = shost->hostt;
-	struct scsi_host_cmd_pool *pool;
-
-	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
-	if (!pool)
-		return NULL;
-
-	pool->cmd_name = kasprintf(GFP_KERNEL, "%s_cmd", hostt->proc_name);
-	if (!pool->cmd_name) {
-		scsi_free_host_cmd_pool(pool);
-		return NULL;
-	}
-
-	if (hostt->cmd_size)
-		hostt->cmd_pool = pool;
-
-	return pool;
-}
-
-static struct scsi_host_cmd_pool *
-scsi_get_host_cmd_pool(struct Scsi_Host *shost)
-{
-	struct scsi_host_template *hostt = shost->hostt;
-	struct scsi_host_cmd_pool *retval = NULL, *pool;
-	size_t cmd_size = sizeof(struct scsi_cmnd) + hostt->cmd_size;
-
-	/*
-	 * Select a command slab for this host and create it if not
-	 * yet existent.
-	 */
-	mutex_lock(&host_cmd_pool_mutex);
-	pool = scsi_find_host_cmd_pool(shost);
-	if (!pool) {
-		pool = scsi_alloc_host_cmd_pool(shost);
-		if (!pool)
-			goto out;
-	}
-
-	if (!pool->users) {
-		pool->cmd_slab = kmem_cache_create(pool->cmd_name, cmd_size, 0,
-						   SLAB_HWCACHE_ALIGN, NULL);
-		if (!pool->cmd_slab)
-			goto out_free_pool;
-	}
-
-	pool->users++;
-	retval = pool;
-out:
-	mutex_unlock(&host_cmd_pool_mutex);
-	return retval;
-
-out_free_pool:
-	if (hostt->cmd_size) {
-		scsi_free_host_cmd_pool(pool);
-		hostt->cmd_pool = NULL;
-	}
-	goto out;
-}
-
-static void scsi_put_host_cmd_pool(struct Scsi_Host *shost)
-{
-	struct scsi_host_template *hostt = shost->hostt;
-	struct scsi_host_cmd_pool *pool;
-
-	mutex_lock(&host_cmd_pool_mutex);
-	pool = scsi_find_host_cmd_pool(shost);
-
-	/*
-	 * This may happen if a driver has a mismatched get and put
-	 * of the command pool; the driver should be implicated in
-	 * the stack trace
-	 */
-	BUG_ON(pool->users == 0);
-
-	if (!--pool->users) {
-		kmem_cache_destroy(pool->cmd_slab);
-		if (hostt->cmd_size) {
-			scsi_free_host_cmd_pool(pool);
-			hostt->cmd_pool = NULL;
-		}
-	}
-	mutex_unlock(&host_cmd_pool_mutex);
-}
-
-/**
- * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
- * @shost: host to allocate the freelist for.
- *
- * Description: The command freelist protects against system-wide out of memory
- * deadlock by preallocating one SCSI command structure for each host, so the
- * system can always write to a swap file on a device associated with that host.
- *
- * Returns:	Nothing.
- */
-int scsi_setup_command_freelist(struct Scsi_Host *shost)
-{
-	struct scsi_cmnd *cmd;
-
-	spin_lock_init(&shost->free_list_lock);
-	INIT_LIST_HEAD(&shost->free_list);
-
-	shost->cmd_pool = scsi_get_host_cmd_pool(shost);
-	if (!shost->cmd_pool)
-		return -ENOMEM;
-
-	/*
-	 * Get one backup command for this host.
-	 */
-	cmd = scsi_host_alloc_command(shost, GFP_KERNEL);
-	if (!cmd) {
-		scsi_put_host_cmd_pool(shost);
-		shost->cmd_pool = NULL;
-		return -ENOMEM;
-	}
-	list_add(&cmd->list, &shost->free_list);
-	return 0;
-}
-
-/**
- * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
- * @shost: host whose freelist is going to be destroyed
- */
-void scsi_destroy_command_freelist(struct Scsi_Host *shost)
-{
-	/*
-	 * If cmd_pool is NULL the free list was not initialized, so
-	 * do not attempt to release resources.
-	 */
-	if (!shost->cmd_pool)
-		return;
-
-	while (!list_empty(&shost->free_list)) {
-		struct scsi_cmnd *cmd;
-
-		cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
-		list_del_init(&cmd->list);
-		scsi_host_free_command(shost, cmd);
-	}
-	shost->cmd_pool = NULL;
-	scsi_put_host_cmd_pool(shost);
 }
 
 #ifdef CONFIG_SCSI_LOGGING

drivers/scsi/scsi_error.c

@@ -2331,7 +2331,7 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
 {
 	struct scsi_cmnd *scmd;
 	struct Scsi_Host *shost = dev->host;
-	struct request req;
+	struct request *rq;
 	unsigned long flags;
 	int error = 0, rtn, val;
 
@@ -2346,14 +2346,16 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
 		return -EIO;
 
 	error = -EIO;
-	scmd = scsi_get_command(dev, GFP_KERNEL);
-	if (!scmd)
+	rq = kzalloc(sizeof(struct request) + sizeof(struct scsi_cmnd) +
+			shost->hostt->cmd_size, GFP_KERNEL);
+	if (!rq)
 		goto out_put_autopm_host;
+	blk_rq_init(NULL, rq);
 
-	blk_rq_init(NULL, &req);
-	scmd->request = &req;
-
-	scmd->cmnd = req.cmd;
+	scmd = (struct scsi_cmnd *)(rq + 1);
+	scsi_init_command(dev, scmd);
+	scmd->request = rq;
+	scmd->cmnd = rq->cmd;
 
 	scmd->scsi_done		= scsi_reset_provider_done_command;
 	memset(&scmd->sdb, 0, sizeof(scmd->sdb));
@@ -2413,6 +2415,7 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
 	scsi_run_host_queues(shost);
 
 	scsi_put_command(scmd);
+	kfree(rq);
 
 out_put_autopm_host:
 	scsi_autopm_put_host(shost);

drivers/scsi/scsi_lib.c

@@ -37,8 +37,7 @@
 #include "scsi_priv.h"
 #include "scsi_logging.h"
 
-
-struct kmem_cache *scsi_sdb_cache;
+static struct kmem_cache *scsi_sdb_cache;
 static struct kmem_cache *scsi_sense_cache;
 static struct kmem_cache *scsi_sense_isadma_cache;
 static DEFINE_MUTEX(scsi_sense_cache_mutex);
@@ -50,14 +49,14 @@ scsi_select_sense_cache(struct Scsi_Host *shost)
 		scsi_sense_isadma_cache : scsi_sense_cache;
 }
 
-void scsi_free_sense_buffer(struct Scsi_Host *shost,
+static void scsi_free_sense_buffer(struct Scsi_Host *shost,
 		unsigned char *sense_buffer)
 {
 	kmem_cache_free(scsi_select_sense_cache(shost), sense_buffer);
 }
 
-unsigned char *scsi_alloc_sense_buffer(struct Scsi_Host *shost, gfp_t gfp_mask,
-		int numa_node)
+static unsigned char *scsi_alloc_sense_buffer(struct Scsi_Host *shost,
+	gfp_t gfp_mask, int numa_node)
 {
 	return kmem_cache_alloc_node(scsi_select_sense_cache(shost), gfp_mask,
 			numa_node);
@@ -697,14 +696,13 @@ static bool scsi_end_request(struct request *req, int error,
 
 		if (bidi_bytes)
 			scsi_release_bidi_buffers(cmd);
+		scsi_release_buffers(cmd);
+		scsi_put_command(cmd);
 
 		spin_lock_irqsave(q->queue_lock, flags);
 		blk_finish_request(req, error);
 		spin_unlock_irqrestore(q->queue_lock, flags);
 
-		scsi_release_buffers(cmd);
-
-		scsi_put_command(cmd);
 		scsi_run_queue(q);
 	}
 
@@ -1161,34 +1159,22 @@ err_exit:
 }
 EXPORT_SYMBOL(scsi_init_io);
 
-static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
-		struct request *req)
+void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
 {
-	struct scsi_cmnd *cmd;
-
-	if (!req->special) {
-		/* Bail if we can't get a reference to the device */
-		if (!get_device(&sdev->sdev_gendev))
-			return NULL;
-
-		cmd = scsi_get_command(sdev, GFP_ATOMIC);
-		if (unlikely(!cmd)) {
-			put_device(&sdev->sdev_gendev);
-			return NULL;
-		}
-		req->special = cmd;
-	} else {
-		cmd = req->special;
-	}
-
-	/* pull a tag out of the request if we have one */
-	cmd->tag = req->tag;
-	cmd->request = req;
+	void *buf = cmd->sense_buffer;
+	void *prot = cmd->prot_sdb;
+	unsigned long flags;
 
-	cmd->cmnd = req->cmd;
-	cmd->prot_op = SCSI_PROT_NORMAL;
+	memset(cmd, 0, sizeof(*cmd));
+	cmd->device = dev;
+	cmd->sense_buffer = buf;
+	cmd->prot_sdb = prot;
+	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
+	cmd->jiffies_at_alloc = jiffies;
 
-	return cmd;
+	spin_lock_irqsave(&dev->list_lock, flags);
+	list_add_tail(&cmd->list, &dev->cmd_list);
+	spin_unlock_irqrestore(&dev->list_lock, flags);
 }
 
 static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
@@ -1349,19 +1335,29 @@ scsi_prep_return(struct request_queue *q, struct request *req, int ret)
 static int scsi_prep_fn(struct request_queue *q, struct request *req)
 {
 	struct scsi_device *sdev = q->queuedata;
-	struct scsi_cmnd *cmd;
+	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
 	int ret;
 
 	ret = scsi_prep_state_check(sdev, req);
 	if (ret != BLKPREP_OK)
 		goto out;
 
-	cmd = scsi_get_cmd_from_req(sdev, req);
-	if (unlikely(!cmd)) {
-		ret = BLKPREP_DEFER;
-		goto out;
+	if (!req->special) {
+		/* Bail if we can't get a reference to the device */
+		if (unlikely(!get_device(&sdev->sdev_gendev))) {
+			ret = BLKPREP_DEFER;
+			goto out;
+		}
+
+		scsi_init_command(sdev, cmd);
+		req->special = cmd;
 	}
 
+	cmd->tag = req->tag;
+	cmd->request = req;
+	cmd->cmnd = req->cmd;
+	cmd->prot_op = SCSI_PROT_NORMAL;
+
 	ret = scsi_setup_cmnd(sdev, req);
 out:
 	return scsi_prep_return(q, req, ret);
@@ -2119,15 +2115,61 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(__scsi_init_queue);
 
+static int scsi_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
+{
+	struct Scsi_Host *shost = q->rq_alloc_data;
+	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+
+	memset(cmd, 0, sizeof(*cmd));
+
+	cmd->sense_buffer = scsi_alloc_sense_buffer(shost, gfp, NUMA_NO_NODE);
+	if (!cmd->sense_buffer)
+		goto fail;
+
+	if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
+		cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp);
+		if (!cmd->prot_sdb)
+			goto fail_free_sense;
+	}
+
+	return 0;
+
+fail_free_sense:
+	scsi_free_sense_buffer(shost, cmd->sense_buffer);
+fail:
+	return -ENOMEM;
+}
+
+static void scsi_exit_rq(struct request_queue *q, struct request *rq)
+{
+	struct Scsi_Host *shost = q->rq_alloc_data;
+	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+
+	if (cmd->prot_sdb)
+		kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
+	scsi_free_sense_buffer(shost, cmd->sense_buffer);
+}
+
 struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
 {
+	struct Scsi_Host *shost = sdev->host;
 	struct request_queue *q;
 
-	q = blk_init_queue(scsi_request_fn, NULL);
+	q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE);
 	if (!q)
 		return NULL;
+	q->cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
+	q->rq_alloc_data = shost;
+	q->request_fn = scsi_request_fn;
+	q->init_rq_fn = scsi_init_rq;
+	q->exit_rq_fn = scsi_exit_rq;
+
+	if (blk_init_allocated_queue(q) < 0) {
+		blk_cleanup_queue(q);
+		return NULL;
+	}
 
-	__scsi_init_queue(sdev->host, q);
+	__scsi_init_queue(shost, q);
 	blk_queue_prep_rq(q, scsi_prep_fn);
 	blk_queue_unprep_rq(q, scsi_unprep_fn);
 	blk_queue_softirq_done(q, scsi_softirq_done);

drivers/scsi/scsi_priv.h

@@ -30,13 +30,8 @@ extern void scsi_exit_hosts(void);
 
 /* scsi.c */
 extern bool scsi_use_blk_mq;
-void scsi_free_sense_buffer(struct Scsi_Host *shost,
-		unsigned char *sense_buffer);
-unsigned char *scsi_alloc_sense_buffer(struct Scsi_Host *shost, gfp_t gfp_mask,
-		int numa_node);
 int scsi_init_sense_cache(struct Scsi_Host *shost);
-extern int scsi_setup_command_freelist(struct Scsi_Host *shost);
-extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);
+void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd);
 #ifdef CONFIG_SCSI_LOGGING
 void scsi_log_send(struct scsi_cmnd *cmd);
 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition);
@@ -101,7 +96,6 @@ extern void scsi_exit_queue(void);
 extern void scsi_evt_thread(struct work_struct *work);
 struct request_queue;
 struct request;
-extern struct kmem_cache *scsi_sdb_cache;
 
 /* scsi_proc.c */
 #ifdef CONFIG_SCSI_PROC_FS

include/scsi/scsi_host.h

@@ -551,9 +551,6 @@ struct Scsi_Host {
 	struct list_head	__devices;
 	struct list_head	__targets;
 	
-	struct scsi_host_cmd_pool *cmd_pool;
-	spinlock_t		free_list_lock;
-	struct list_head	free_list; /* backup store of cmd structs */
 	struct list_head	starved_list;
 
 	spinlock_t		default_lock;