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scsi: target: Make the session shutdown code also wait for commands that are being aborted 

Target drivers must call target_sess_cmd_list_set_waiting() and
target_wait_for_sess_cmds() before freeing a session. Since freeing a
session is only safe after all commands that are associated with a session
have finished, make target_wait_for_sess_cmds() also wait for commands that
are being aborted. Instead of setting a flag in each pending command from
target_sess_cmd_list_set_waiting() and waiting in
target_wait_for_sess_cmds() on a per-command completion, only set a
per-session flag in the former function and wait on a per-session
completion in the latter function. This change is safe because once a SCSI
initiator system has submitted a command a target system is always allowed
to execute it to completion. See also commit 0f4a943168 ("target: Fix
remote-port TMR ABORT + se_cmd fabric stop").

This patch is based on the following two patches:

* Bart Van Assche, target: Simplify session shutdown code, February 19, 2015
  (8df5463d7d).

* Christoph Hellwig, target: Rework session shutdown code, December 7, 2015
  (http://thread.gmane.org/gmane.linux.scsi.target.devel/10695).

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2018-06-22 14:52:53 -07:00 committed by Martin K. Petersen
parent d1bff07f38
commit 00d909a107
3 changed files with 23 additions and 60 deletions
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5
drivers/target/target_core_tmr.c
View File

@ -142,7 +142,7 @@ static bool __target_check_io_state(struct se_cmd *se_cmd,
return false;
}
}
if (sess->sess_tearing_down || se_cmd->cmd_wait_set) {
if (sess->sess_tearing_down) {
pr_debug("Attempted to abort io tag: %llu already shutdown,"
" skipping\n", se_cmd->tag);
spin_unlock(&se_cmd->t_state_lock);
@ -187,7 +187,6 @@ void core_tmr_abort_task(
if (!__target_check_io_state(se_cmd, se_sess, 0))
continue;
list_del_init(&se_cmd->se_cmd_list);
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
cancel_work_sync(&se_cmd->work);
@ -259,7 +258,7 @@ static void core_tmr_drain_tmr_list(
spin_unlock(&sess->sess_cmd_lock);
continue;
}
if (sess->sess_tearing_down || cmd->cmd_wait_set) {
if (sess->sess_tearing_down) {
spin_unlock(&cmd->t_state_lock);
spin_unlock(&sess->sess_cmd_lock);
continue;

75
drivers/target/target_core_transport.c
View File

@ -235,8 +235,8 @@ void transport_init_session(struct se_session *se_sess)
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);
init_waitqueue_head(&se_sess->cmd_list_wq);
}
EXPORT_SYMBOL(transport_init_session);
@ -2728,13 +2728,15 @@ static void target_release_cmd_kref(struct kref *kref)
if (se_sess) {
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
list_del_init(&se_cmd->se_cmd_list);
if (list_empty(&se_sess->sess_cmd_list))
wake_up(&se_sess->cmd_list_wq);
spin_lock(&se_cmd->t_state_lock);
fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP) &&
(se_cmd->transport_state & CMD_T_ABORTED);
spin_unlock(&se_cmd->t_state_lock);
if (se_cmd->cmd_wait_set || fabric_stop) {
if (fabric_stop) {
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
target_free_cmd_mem(se_cmd);
complete(&se_cmd->cmd_wait_comp);
@ -2863,78 +2865,41 @@ void target_show_cmd(const char *pfx, struct se_cmd *cmd)
EXPORT_SYMBOL(target_show_cmd);
/**
* target_sess_cmd_list_set_waiting - Flag all commands in
* sess_cmd_list to complete cmd_wait_comp. Set
* sess_tearing_down so no more commands are queued.
* target_sess_cmd_list_set_waiting - Set sess_tearing_down so no new commands are queued.
* @se_sess: session to flag
*/
void target_sess_cmd_list_set_waiting(struct se_session *se_sess)
{
struct se_cmd *se_cmd, *tmp_cmd;
unsigned long flags;
int rc;
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
if (se_sess->sess_tearing_down) {
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
return;
}
se_sess->sess_tearing_down = 1;
list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);
list_for_each_entry_safe(se_cmd, tmp_cmd,
&se_sess->sess_wait_list, se_cmd_list) {
rc = kref_get_unless_zero(&se_cmd->cmd_kref);
if (rc) {
se_cmd->cmd_wait_set = 1;
spin_lock(&se_cmd->t_state_lock);
se_cmd->transport_state |= CMD_T_FABRIC_STOP;
spin_unlock(&se_cmd->t_state_lock);
} else
list_del_init(&se_cmd->se_cmd_list);
}
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
EXPORT_SYMBOL(target_sess_cmd_list_set_waiting);
/**
* target_wait_for_sess_cmds - Wait for outstanding descriptors
* target_wait_for_sess_cmds - Wait for outstanding commands
* @se_sess: session to wait for active I/O
*/
void target_wait_for_sess_cmds(struct se_session *se_sess)
{
struct se_cmd *se_cmd, *tmp_cmd;
unsigned long flags;
bool tas;
struct se_cmd *cmd;
int ret;
list_for_each_entry_safe(se_cmd, tmp_cmd,
&se_sess->sess_wait_list, 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));
spin_lock_irqsave(&se_cmd->t_state_lock, flags);
tas = (se_cmd->transport_state & CMD_T_TAS);
spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
if (!target_put_sess_cmd(se_cmd)) {
if (tas)
target_put_sess_cmd(se_cmd);
}
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);
}
spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
WARN_ON(!list_empty(&se_sess->sess_cmd_list));
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
WARN_ON_ONCE(!se_sess->sess_tearing_down);
spin_lock_irq(&se_sess->sess_cmd_lock);
do {
ret = wait_event_interruptible_lock_irq_timeout(
se_sess->cmd_list_wq,
list_empty(&se_sess->sess_cmd_list),
se_sess->sess_cmd_lock, 180 * HZ);
list_for_each_entry(cmd, &se_sess->sess_cmd_list, se_cmd_list)
target_show_cmd("session shutdown: still waiting for ",
cmd);
} while (ret <= 0);
spin_unlock_irq(&se_sess->sess_cmd_lock);
}
EXPORT_SYMBOL(target_wait_for_sess_cmds);

3
include/target/target_core_base.h
View File

@ -443,7 +443,6 @@ struct se_cmd {
u8 scsi_asc;
u8 scsi_ascq;
u16 scsi_sense_length;
unsigned cmd_wait_set:1;
unsigned unknown_data_length:1;
bool state_active:1;
u64 tag; /* SAM command identifier aka task tag */
@ -606,8 +605,8 @@ struct se_session {
struct list_head sess_list;
struct list_head sess_acl_list;
struct list_head sess_cmd_list;
struct list_head sess_wait_list;
spinlock_t sess_cmd_lock;
wait_queue_head_t cmd_list_wq;
void *sess_cmd_map;
struct sbitmap_queue sess_tag_pool;
};