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Commit a6d9bb1c authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Fix LUN_RESET active TMR descriptor handling 



This patch fixes a NULL pointer se_cmd->cmd_kref < 0
refcount bug during TMR LUN_RESET with active TMRs,
triggered during se_cmd + se_tmr_req descriptor
shutdown + release via core_tmr_drain_tmr_list().

To address this bug, go ahead and obtain a local
kref_get_unless_zero(&se_cmd->cmd_kref) for active I/O
to set CMD_T_ABORTED, and transport_wait_for_tasks()
followed by the final target_put_sess_cmd() to drop
the local ->cmd_kref.

Also add two new checks within target_tmr_work() to
avoid CMD_T_ABORTED -> TFO->queue_tm_rsp() callbacks
ahead of invoking the backend -> fabric put in
transport_cmd_check_stop_to_fabric().

For good measure, also change core_tmr_release_req()
to use list_del_init() ahead of se_tmr_req memory
free.

Reviewed-by: default avatarQuinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent febe562c

drivers/target/target_core_tmr.c

+21 −1
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr) 


	if (dev) {

		spin_lock_irqsave(&dev->se_tmr_lock, flags);

		list_del(&tmr->tmr_list);

		list_del_init(&tmr->tmr_list);

		spin_unlock_irqrestore(&dev->se_tmr_lock, flags);

	}
@@ -194,9 +194,11 @@ static void core_tmr_drain_tmr_list( 
	struct list_head *preempt_and_abort_list)

{

	LIST_HEAD(drain_tmr_list);

	struct se_session *sess;

	struct se_tmr_req *tmr_p, *tmr_pp;

	struct se_cmd *cmd;

	unsigned long flags;

	bool rc;

	/*

	 * Release all pending and outgoing TMRs aside from the received

	 * LUN_RESET tmr..
@@ -222,17 +224,31 @@ static void core_tmr_drain_tmr_list( 
		if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))

			continue;



		sess = cmd->se_sess;

		if (WARN_ON_ONCE(!sess))

			continue;



		spin_lock(&sess->sess_cmd_lock);

		spin_lock(&cmd->t_state_lock);

		if (!(cmd->transport_state & CMD_T_ACTIVE)) {

			spin_unlock(&cmd->t_state_lock);

			spin_unlock(&sess->sess_cmd_lock);

			continue;

		}

		if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {

			spin_unlock(&cmd->t_state_lock);

			spin_unlock(&sess->sess_cmd_lock);

			continue;

		}

		cmd->transport_state |= CMD_T_ABORTED;

		spin_unlock(&cmd->t_state_lock);



		rc = kref_get_unless_zero(&cmd->cmd_kref);

		spin_unlock(&sess->sess_cmd_lock);

		if (!rc) {

			printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");

			continue;

		}

		list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);

	}

	spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
@@ -246,7 +262,11 @@ static void core_tmr_drain_tmr_list( 
			(preempt_and_abort_list) ? "Preempt" : "", tmr_p,

			tmr_p->function, tmr_p->response, cmd->t_state);



		cancel_work_sync(&cmd->work);

		transport_wait_for_tasks(cmd);



		transport_cmd_finish_abort(cmd, 1);

		target_put_sess_cmd(cmd);

	}

}

drivers/target/target_core_transport.c

+17 −0
Original line number Diff line number Diff line
@@ -2900,8 +2900,17 @@ static void target_tmr_work(struct work_struct *work) 
	struct se_cmd *cmd = container_of(work, struct se_cmd, work);

	struct se_device *dev = cmd->se_dev;

	struct se_tmr_req *tmr = cmd->se_tmr_req;

	unsigned long flags;

	int ret;



	spin_lock_irqsave(&cmd->t_state_lock, flags);

	if (cmd->transport_state & CMD_T_ABORTED) {

		tmr->response = TMR_FUNCTION_REJECTED;

		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

		goto check_stop;

	}

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);



	switch (tmr->function) {

	case TMR_ABORT_TASK:

		core_tmr_abort_task(dev, tmr, cmd->se_sess);
@@ -2934,9 +2943,17 @@ static void target_tmr_work(struct work_struct *work) 
		break;

	}



	spin_lock_irqsave(&cmd->t_state_lock, flags);

	if (cmd->transport_state & CMD_T_ABORTED) {

		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

		goto check_stop;

	}

	cmd->t_state = TRANSPORT_ISTATE_PROCESSING;

	spin_unlock_irqrestore(&cmd->t_state_lock, flags);



	cmd->se_tfo->queue_tm_rsp(cmd);



check_stop:

	transport_cmd_check_stop_to_fabric(cmd);

}