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>

Author: Christoph Hellwig

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