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scsi: allocate scsi_cmnd structures as part of struct request
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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>
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@axboe
Christoph Hellwig authored and axboe committed Jan 27, 2017
1 parent d48777a commit e9c787e
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Showing 6 changed files with 95 additions and 394 deletions.
20 changes: 2 additions & 18 deletions drivers/scsi/hosts.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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);
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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);
Expand Down
319 changes: 0 additions & 319 deletions drivers/scsi/scsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
Expand Down
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