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[SCSI] add support for per-host cmd pools

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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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Christoph Hellwig 2014-02-20 14:21:01 -08:00 committed by James Bottomley
parent 7c28334122
commit 89d9a56795
2 changed files with 84 additions and 19 deletions
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96
drivers/scsi/scsi.c
View File

@ -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

7
include/scsi/scsi_host.h
View File

@ -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;
};
/*