scsi: qla2xxx: Fixup locking for session deletion

Commit d8630bb95f46 ('Serialize session deletion by using work_lock')
tries to fixup a deadlock when deleting sessions, but fails to take into
account the locking rules. This patch resolves the situation by
introducing a separate lock for processing the GNLIST response, and
ensures that sess_lock is released before calling
qlt_schedule_sess_delete().

Cc: Himanshu Madhani <himanshu.madhani@cavium.com>
Cc: Quinn Tran <quinn.tran@cavium.com>
Fixes: d8630bb95f46 ("scsi: qla2xxx: Serialize session deletion by using work_lock")
Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index 896b2d8bd803..b49ac85f3de2 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -1224,10 +1224,10 @@ static void qla24xx_chk_fcp_state(struct fc_port *sess)
 	}
 }
 
-/* ha->tgt.sess_lock supposed to be held on entry */
 void qlt_schedule_sess_for_deletion(struct fc_port *sess)
 {
 	struct qla_tgt *tgt = sess->tgt;
+	struct qla_hw_data *ha = sess->vha->hw;
 	unsigned long flags;
 
 	if (sess->disc_state == DSC_DELETE_PEND)
@@ -1244,16 +1244,16 @@ void qlt_schedule_sess_for_deletion(struct fc_port *sess)
 			return;
 	}
 
+	spin_lock_irqsave(&ha->tgt.sess_lock, flags);
 	if (sess->deleted == QLA_SESS_DELETED)
 		sess->logout_on_delete = 0;
 
-	spin_lock_irqsave(&sess->vha->work_lock, flags);
 	if (sess->deleted == QLA_SESS_DELETION_IN_PROGRESS) {
-		spin_unlock_irqrestore(&sess->vha->work_lock, flags);
+		spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 		return;
 	}
 	sess->deleted = QLA_SESS_DELETION_IN_PROGRESS;
-	spin_unlock_irqrestore(&sess->vha->work_lock, flags);
+	spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 
 	sess->disc_state = DSC_DELETE_PEND;
 
@@ -1262,13 +1262,10 @@ void qlt_schedule_sess_for_deletion(struct fc_port *sess)
 	ql_dbg(ql_dbg_tgt, sess->vha, 0xe001,
 	    "Scheduling sess %p for deletion\n", sess);
 
-	/* use cancel to push work element through before re-queue */
-	cancel_work_sync(&sess->del_work);
 	INIT_WORK(&sess->del_work, qla24xx_delete_sess_fn);
-	queue_work(sess->vha->hw->wq, &sess->del_work);
+	WARN_ON(!queue_work(sess->vha->hw->wq, &sess->del_work));
 }
 
-/* ha->tgt.sess_lock supposed to be held on entry */
 static void qlt_clear_tgt_db(struct qla_tgt *tgt)
 {
 	struct fc_port *sess;
@@ -1451,8 +1448,8 @@ qlt_fc_port_deleted(struct scsi_qla_host *vha, fc_port_t *fcport, int max_gen)
 	ql_dbg(ql_dbg_tgt_mgt, vha, 0xf008, "qla_tgt_fc_port_deleted %p", sess);
 
 	sess->local = 1;
-	qlt_schedule_sess_for_deletion(sess);
 	spin_unlock_irqrestore(&vha->hw->tgt.sess_lock, flags);
+	qlt_schedule_sess_for_deletion(sess);
 }
 
 static inline int test_tgt_sess_count(struct qla_tgt *tgt)
@@ -1512,10 +1509,8 @@ int qlt_stop_phase1(struct qla_tgt *tgt)
 	 * Lock is needed, because we still can get an incoming packet.
 	 */
 	mutex_lock(&vha->vha_tgt.tgt_mutex);
-	spin_lock_irqsave(&ha->tgt.sess_lock, flags);
 	tgt->tgt_stop = 1;
 	qlt_clear_tgt_db(tgt);
-	spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 	mutex_unlock(&vha->vha_tgt.tgt_mutex);
 	mutex_unlock(&qla_tgt_mutex);