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target: Add generic active I/O shutdown logic

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This patch adds the initial pieces of generic active I/O shutdown logic.
This is intended to be a 'opt-in' feature for fabric modules that
includes the following functions to provide a mechinism for fabric
modules to track se_cmd via se_session->sess_cmd_list:

*) target_get_sess_cmd() - Add se_cmd to sess->sess_cmd_list, called
   from fabric module incoming I/O path.
*) target_put_sess_cmd() - Check for completion or drop se_cmd from
   ->sess_cmd_list
*) target_splice_sess_cmd_list() - Splice active I/O list from
   ->sess_cmd_list to ->sess_wait_list, can called with HW fabric
   lock held.
*) target_wait_for_sess_cmds() - Walk ->sess_wait_list waiting on
   individual ->cmd_wait_comp.  Optional transport_wait_for_tasks()
   call.

target_splice_sess_cmd_list() is allowed to be called under HW fabric
lock, and performs the splice into se_sess->sess_wait_list and set
se_cmd->cmd_wait_set.  Then target_wait_for_sess_cmds() walks the list
waiting for individual target_put_sess_cmd() fabric callbacks to
complete.

It also adds TFO->check_release_cmd() to split the completion and memory
release calls, where a fabric module uses target_put_sess_cmd() to check
for I/O completion during session shutdown.  This is currently pushed out
into fabric modules as current fabric code may sleep here waiting for
TFO->check_stop_free() to complete in main response path, and because
target_wait_for_sess_cmds() calling TFO->release_cmd() to free fabric
descriptor memory directly.

Cc: Christoph Hellwig <[email protected]>
Cc: Roland Dreier <[email protected]>
Signed-off-by: Nicholas A. Bellinger <[email protected]>
This commit is contained in:
Nicholas Bellinger 2011-11-02 21:52:08 -07:00
commit a17f091d1a
4 changed files with 145 additions and 6 deletions
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132
drivers/target/target_core_transport.c
View file

@ -268,6 +268,9 @@ struct se_session *transport_init_session(void)
}
INIT_LIST_HEAD(&se_sess->sess_list);
INIT_LIST_HEAD(&se_sess->sess_acl_list);
INIT_LIST_HEAD(&se_sess->sess_cmd_list);
INIT_LIST_HEAD(&se_sess->sess_wait_list);
spin_lock_init(&se_sess->sess_cmd_lock);
return se_sess;
}
@ -1505,11 +1508,12 @@ void transport_init_se_cmd(
INIT_LIST_HEAD(&cmd->se_ordered_node);
INIT_LIST_HEAD(&cmd->se_qf_node);
INIT_LIST_HEAD(&cmd->se_queue_node);
INIT_LIST_HEAD(&cmd->se_cmd_list);
INIT_LIST_HEAD(&cmd->t_task_list);
init_completion(&cmd->transport_lun_fe_stop_comp);
init_completion(&cmd->transport_lun_stop_comp);
init_completion(&cmd->t_transport_stop_comp);
init_completion(&cmd->cmd_wait_comp);
spin_lock_init(&cmd->t_state_lock);
atomic_set(&cmd->transport_dev_active, 1);
@ -3950,6 +3954,14 @@ void transport_release_cmd(struct se_cmd *cmd)
core_tmr_release_req(cmd->se_tmr_req);
if (cmd->t_task_cdb != cmd->__t_task_cdb)
kfree(cmd->t_task_cdb);
/*
* Check if target_wait_for_sess_cmds() is expecting to
* release se_cmd directly here..
*/
if (cmd->check_release != 0 && cmd->se_tfo->check_release_cmd)
if (cmd->se_tfo->check_release_cmd(cmd) != 0)
return;
cmd->se_tfo->release_cmd(cmd);
}
EXPORT_SYMBOL(transport_release_cmd);
@ -3977,6 +3989,114 @@ void transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
}
EXPORT_SYMBOL(transport_generic_free_cmd);
/* target_get_sess_cmd - Add command to active ->sess_cmd_list
* @se_sess: session to reference
* @se_cmd: command descriptor to add
*/
void target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
{
unsigned long flags;
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
se_cmd->check_release = 1;
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
EXPORT_SYMBOL(target_get_sess_cmd);
/* target_put_sess_cmd - Check for active I/O shutdown or list delete
* @se_sess: session to reference
* @se_cmd: command descriptor to drop
*/
int target_put_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
{
unsigned long flags;
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
if (list_empty(&se_cmd->se_cmd_list)) {
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
WARN_ON(1);
return 0;
}
if (se_sess->sess_tearing_down && se_cmd->cmd_wait_set) {
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
complete(&se_cmd->cmd_wait_comp);
return 1;
}
list_del(&se_cmd->se_cmd_list);
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
return 0;
}
EXPORT_SYMBOL(target_put_sess_cmd);
/* target_splice_sess_cmd_list - Split active cmds into sess_wait_list
* @se_sess: session to split
*/
void target_splice_sess_cmd_list(struct se_session *se_sess)
{
struct se_cmd *se_cmd;
unsigned long flags;
WARN_ON(!list_empty(&se_sess->sess_wait_list));
INIT_LIST_HEAD(&se_sess->sess_wait_list);
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
se_sess->sess_tearing_down = 1;
list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);
list_for_each_entry(se_cmd, &se_sess->sess_wait_list, se_cmd_list)
se_cmd->cmd_wait_set = 1;
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
EXPORT_SYMBOL(target_splice_sess_cmd_list);
/* target_wait_for_sess_cmds - Wait for outstanding descriptors
* @se_sess: session to wait for active I/O
* @wait_for_tasks: Make extra transport_wait_for_tasks call
*/
void target_wait_for_sess_cmds(
struct se_session *se_sess,
int wait_for_tasks)
{
struct se_cmd *se_cmd, *tmp_cmd;
bool rc = false;
list_for_each_entry_safe(se_cmd, tmp_cmd,
&se_sess->sess_wait_list, se_cmd_list) {
list_del(&se_cmd->se_cmd_list);
pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
" %d\n", se_cmd, se_cmd->t_state,
se_cmd->se_tfo->get_cmd_state(se_cmd));
if (wait_for_tasks) {
pr_debug("Calling transport_wait_for_tasks se_cmd: %p t_state: %d,"
" fabric state: %d\n", se_cmd, se_cmd->t_state,
se_cmd->se_tfo->get_cmd_state(se_cmd));
rc = transport_wait_for_tasks(se_cmd);
pr_debug("After transport_wait_for_tasks se_cmd: %p t_state: %d,"
" fabric state: %d\n", se_cmd, se_cmd->t_state,
se_cmd->se_tfo->get_cmd_state(se_cmd));
}
if (!rc) {
wait_for_completion(&se_cmd->cmd_wait_comp);
pr_debug("After cmd_wait_comp: se_cmd: %p t_state: %d"
" fabric state: %d\n", se_cmd, se_cmd->t_state,
se_cmd->se_tfo->get_cmd_state(se_cmd));
}
se_cmd->se_tfo->release_cmd(se_cmd);
}
}
EXPORT_SYMBOL(target_wait_for_sess_cmds);
/* transport_lun_wait_for_tasks():
*
* Called from ConfigFS context to stop the passed struct se_cmd to allow
@ -4153,14 +4273,14 @@ int transport_clear_lun_from_sessions(struct se_lun *lun)
* Called from frontend fabric context to wait for storage engine
* to pause and/or release frontend generated struct se_cmd.
*/
void transport_wait_for_tasks(struct se_cmd *cmd)
bool transport_wait_for_tasks(struct se_cmd *cmd)
{
unsigned long flags;
spin_lock_irqsave(&cmd->t_state_lock, flags);
if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD) && !(cmd->se_tmr_req)) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return;
return false;
}
/*
* Only perform a possible wait_for_tasks if SCF_SUPPORTED_SAM_OPCODE
@ -4168,7 +4288,7 @@ void transport_wait_for_tasks(struct se_cmd *cmd)
*/
if (!(cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) && !cmd->se_tmr_req) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return;
return false;
}
/*
* If we are already stopped due to an external event (ie: LUN shutdown)
@ -4211,7 +4331,7 @@ void transport_wait_for_tasks(struct se_cmd *cmd)
if (!atomic_read(&cmd->t_transport_active) ||
atomic_read(&cmd->t_transport_aborted)) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return;
return false;
}
atomic_set(&cmd->t_transport_stop, 1);
@ -4236,6 +4356,8 @@ void transport_wait_for_tasks(struct se_cmd *cmd)
cmd->se_tfo->get_task_tag(cmd));
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return true;
}
EXPORT_SYMBOL(transport_wait_for_tasks);