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target: always allocate a single task
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Simply transport_generic_new_cmd to only allocate a single task.  For normal
unidirection commands nothing changes except that the code is a lot simpler
now.  Any BIDI support that used to work will stop now for the next few
patches at least.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
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Christoph Hellwig authored and Nicholas Bellinger committed May 6, 2012
1 parent 6bb35e0 commit 4101f0a
Showing 1 changed file with 37 additions and 120 deletions.
157 changes: 37 additions & 120 deletions drivers/target/target_core_transport.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1474,29 +1474,6 @@ static inline void transport_generic_prepare_cdb(
}
}

static struct se_task *
transport_generic_get_task(struct se_cmd *cmd,
enum dma_data_direction data_direction)
{
struct se_task *task;
struct se_device *dev = cmd->se_dev;

task = dev->transport->alloc_task(cmd->t_task_cdb);
if (!task) {
pr_err("Unable to allocate struct se_task\n");
return NULL;
}

INIT_LIST_HEAD(&task->t_list);
INIT_LIST_HEAD(&task->t_execute_list);
INIT_LIST_HEAD(&task->t_state_list);
init_completion(&task->task_stop_comp);
task->task_se_cmd = cmd;
task->task_data_direction = data_direction;

return task;
}

static int transport_generic_cmd_sequencer(struct se_cmd *, unsigned char *);

/*
Expand Down Expand Up @@ -3704,68 +3681,6 @@ transport_generic_get_mem(struct se_cmd *cmd)
return -ENOMEM;
}

/*
* Break up cmd into chunks transport can handle
*/
static int
transport_allocate_data_tasks(struct se_cmd *cmd,
enum dma_data_direction data_direction,
struct scatterlist *cmd_sg, unsigned int sgl_nents)
{
struct se_device *dev = cmd->se_dev;
struct se_dev_attrib *attr = &dev->se_sub_dev->se_dev_attrib;
sector_t sectors;
struct se_task *task;
unsigned long flags;

if (transport_cmd_get_valid_sectors(cmd) < 0)
return -EINVAL;

sectors = DIV_ROUND_UP(cmd->data_length, attr->block_size);

BUG_ON(cmd->data_length % attr->block_size);
BUG_ON(sectors > attr->max_sectors);

task = transport_generic_get_task(cmd, data_direction);
if (!task)
return -ENOMEM;

task->task_sg = cmd_sg;
task->task_sg_nents = sgl_nents;

spin_lock_irqsave(&cmd->t_state_lock, flags);
list_add_tail(&task->t_list, &cmd->t_task_list);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);

return 1;
}

static int
transport_allocate_control_task(struct se_cmd *cmd)
{
struct se_task *task;
unsigned long flags;

/* Workaround for handling zero-length control CDBs */
if ((cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB) &&
!cmd->data_length)
return 0;

task = transport_generic_get_task(cmd, cmd->data_direction);
if (!task)
return -ENOMEM;

task->task_sg = cmd->t_data_sg;
task->task_sg_nents = cmd->t_data_nents;

spin_lock_irqsave(&cmd->t_state_lock, flags);
list_add_tail(&task->t_list, &cmd->t_task_list);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);

/* Success! Return number of tasks allocated */
return 1;
}

/*
* Allocate any required resources to execute the command. For writes we
* might not have the payload yet, so notify the fabric via a call to
Expand All @@ -3774,8 +3689,8 @@ transport_allocate_control_task(struct se_cmd *cmd)
int transport_generic_new_cmd(struct se_cmd *cmd)
{
struct se_device *dev = cmd->se_dev;
int task_cdbs, task_cdbs_bidi = 0;
int set_counts = 1;
struct se_task *task;
unsigned long flags;
int ret = 0;

/*
Expand All @@ -3790,35 +3705,9 @@ int transport_generic_new_cmd(struct se_cmd *cmd)
goto out_fail;
}

/*
* For BIDI command set up the read tasks first.
*/
if (cmd->t_bidi_data_sg &&
dev->transport->transport_type != TRANSPORT_PLUGIN_PHBA_PDEV) {
BUG_ON(!(cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB));

task_cdbs_bidi = transport_allocate_data_tasks(cmd,
DMA_FROM_DEVICE, cmd->t_bidi_data_sg,
cmd->t_bidi_data_nents);
if (task_cdbs_bidi <= 0)
goto out_fail;

atomic_inc(&cmd->t_fe_count);
atomic_inc(&cmd->t_se_count);
set_counts = 0;
}

if (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB) {
task_cdbs = transport_allocate_data_tasks(cmd,
cmd->data_direction, cmd->t_data_sg,
cmd->t_data_nents);
} else {
task_cdbs = transport_allocate_control_task(cmd);
}

if (task_cdbs < 0)
goto out_fail;
else if (!task_cdbs && (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB)) {
/* Workaround for handling zero-length control CDBs */
if ((cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB) &&
!cmd->data_length) {
spin_lock_irq(&cmd->t_state_lock);
cmd->t_state = TRANSPORT_COMPLETE;
cmd->transport_state |= CMD_T_ACTIVE;
Expand All @@ -3836,12 +3725,40 @@ int transport_generic_new_cmd(struct se_cmd *cmd)
return 0;
}

if (set_counts) {
atomic_inc(&cmd->t_fe_count);
atomic_inc(&cmd->t_se_count);
if (cmd->se_cmd_flags & SCF_SCSI_DATA_SG_IO_CDB) {
struct se_dev_attrib *attr = &dev->se_sub_dev->se_dev_attrib;

if (transport_cmd_get_valid_sectors(cmd) < 0)
return -EINVAL;

BUG_ON(cmd->data_length % attr->block_size);
BUG_ON(DIV_ROUND_UP(cmd->data_length, attr->block_size) >
attr->max_sectors);
}

task = dev->transport->alloc_task(cmd->t_task_cdb);
if (!task) {
pr_err("Unable to allocate struct se_task\n");
goto out_fail;
}

cmd->t_task_list_num = (task_cdbs + task_cdbs_bidi);
INIT_LIST_HEAD(&task->t_list);
INIT_LIST_HEAD(&task->t_execute_list);
INIT_LIST_HEAD(&task->t_state_list);
init_completion(&task->task_stop_comp);
task->task_se_cmd = cmd;
task->task_data_direction = cmd->data_direction;
task->task_sg = cmd->t_data_sg;
task->task_sg_nents = cmd->t_data_nents;

spin_lock_irqsave(&cmd->t_state_lock, flags);
list_add_tail(&task->t_list, &cmd->t_task_list);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);

atomic_inc(&cmd->t_fe_count);
atomic_inc(&cmd->t_se_count);

cmd->t_task_list_num = 1;
atomic_set(&cmd->t_task_cdbs_left, cmd->t_task_list_num);
atomic_set(&cmd->t_task_cdbs_ex_left, cmd->t_task_list_num);

Expand Down

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