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Commit 00d909a1 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
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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 0f4a9431 ("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
  (https://github.com/bvanassche/linux/commit/8df5463d7d7619f2f1b70cfe5172eaef0aa52815).

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

).

Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: default avatarMike 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: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d1bff07f

drivers/target/target_core_tmr.c

+2 −3
Original line number Diff line number Diff line
@@ -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;

drivers/target/target_core_transport.c

+21 −56
Original line number Diff line number Diff line
@@ -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;



	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);

	}

	struct se_cmd *cmd;

	int ret;



	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);

include/target/target_core_base.h

+1 −2
Original line number Diff line number Diff line
@@ -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;

};