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Commit 89d9a567 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by James Bottomley
Browse files

[SCSI] add support for per-host cmd pools 



This allows drivers to specify the size of their per-command private
data in the host template and then get extra memory allocated for
each command instead of needing another allocation in ->queuecommand.

With the current SCSI code that already does multiple allocations for
each command this probably doesn't make a big performance impact, but
it allows to clean up the drivers, and prepare them for using the
blk-mq infrastructure where the common allocation will make a difference.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 7c283341

drivers/scsi/scsi.c

+77 −19
Original line number Diff line number Diff line
@@ -331,46 +331,103 @@ void scsi_put_command(struct scsi_cmnd *cmd) 
}

EXPORT_SYMBOL(scsi_put_command);



static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)

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;

	if (shost->unchecked_isa_dma)

		return &scsi_cmd_dma_pool;

	return &scsi_cmd_pool;

}



static void

scsi_free_host_cmd_pool(struct scsi_host_cmd_pool *pool)

{

	kfree(pool->sense_name);

	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->name);

	pool->sense_name = kasprintf(GFP_KERNEL, "%s_sense", hostt->name);

	if (!pool->cmd_name || !pool->sense_name) {

		scsi_free_host_cmd_pool(pool);

		return NULL;

	}



	pool->slab_flags = SLAB_HWCACHE_ALIGN;

	if (shost->unchecked_isa_dma) {

		pool->slab_flags |= SLAB_CACHE_DMA;

		pool->gfp_mask = __GFP_DMA;

	}

	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 = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :

		&scsi_cmd_pool;

	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,

						   sizeof(struct scsi_cmnd), 0,

		pool->cmd_slab = kmem_cache_create(pool->cmd_name, cmd_size, 0,

						   pool->slab_flags, NULL);

		if (!pool->cmd_slab)

			goto fail;

			goto out_free_pool;



		pool->sense_slab = kmem_cache_create(pool->sense_name,

						     SCSI_SENSE_BUFFERSIZE, 0,

						     pool->slab_flags, NULL);

		if (!pool->sense_slab) {

			kmem_cache_destroy(pool->cmd_slab);

			goto fail;

		}

		if (!pool->sense_slab)

			goto out_free_slab;

	}



	pool->users++;

	retval = pool;

 fail:

out:

	mutex_unlock(&host_cmd_pool_mutex);

	return retval;



out_free_slab:

	kmem_cache_destroy(pool->cmd_slab);

out_free_pool:

	if (hostt->cmd_size)

		scsi_free_host_cmd_pool(pool);

	goto out;

}



static void scsi_put_host_cmd_pool(gfp_t gfp_mask)

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 = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :

		&scsi_cmd_pool;

	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
@@ -381,6 +438,8 @@ static void scsi_put_host_cmd_pool(gfp_t gfp_mask) 
	if (!--pool->users) {

		kmem_cache_destroy(pool->cmd_slab);

		kmem_cache_destroy(pool->sense_slab);

		if (hostt->cmd_size)

			scsi_free_host_cmd_pool(pool);

	}

	mutex_unlock(&host_cmd_pool_mutex);

}
@@ -397,14 +456,13 @@ static void scsi_put_host_cmd_pool(gfp_t gfp_mask) 
 */

int scsi_setup_command_freelist(struct Scsi_Host *shost)

{

	struct scsi_cmnd *cmd;

	const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;

	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(gfp_mask);



	shost->cmd_pool = scsi_get_host_cmd_pool(shost);

	if (!shost->cmd_pool)

		return -ENOMEM;
@@ -413,7 +471,7 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost) 
	 */

	cmd = scsi_host_alloc_command(shost, gfp_mask);

	if (!cmd) {

		scsi_put_host_cmd_pool(gfp_mask);

		scsi_put_host_cmd_pool(shost);

		shost->cmd_pool = NULL;

		return -ENOMEM;

	}
@@ -442,7 +500,7 @@ void scsi_destroy_command_freelist(struct Scsi_Host *shost) 
		scsi_host_free_command(shost, cmd);

	}

	shost->cmd_pool = NULL;

	scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL);

	scsi_put_host_cmd_pool(shost);

}



#ifdef CONFIG_SCSI_LOGGING

include/scsi/scsi_host.h

+7 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ struct completion; 
struct module;

struct scsi_cmnd;

struct scsi_device;

struct scsi_host_cmd_pool;

struct scsi_target;

struct Scsi_Host;

struct scsi_host_cmd_pool;
@@ -524,6 +525,12 @@ struct scsi_host_template { 
	 *   scsi_netlink.h

	 */

	u64 vendor_id;



	/*

	 * Additional per-command data allocated for the driver.

	 */

	unsigned int cmd_size;

	struct scsi_host_cmd_pool *cmd_pool;

};



/*