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>

4 files changed, 29 insertions, 23 deletions

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index be7d6824581a..3ca4b6a5eddd 100644
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -261,9 +261,9 @@
 struct name_list_extended {
         struct get_name_list_extended *l;
         dma_addr_t              ldma;
-        struct list_head        fcports;        /* protect by sess_list */
+        struct list_head        fcports;
+        spinlock_t              fcports_lock;
         u32                     size;
-        u8                      sent;
 };
 /*
  * Timeout timer counts in seconds
diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 04870621e712..cacf2ccc081b 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -643,8 +643,7 @@ qla24xx_async_gnl_sp_done(void *s, int res)
                     (loop_id & 0x7fff));
         }
 
-        spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
-        vha->gnl.sent = 0;
+        spin_lock_irqsave(&vha->gnl.fcports_lock, flags);
 
         INIT_LIST_HEAD(&h);
         fcport = tf = NULL;
@@ -653,12 +652,16 @@ qla24xx_async_gnl_sp_done(void *s, int res)
 
         list_for_each_entry_safe(fcport, tf, &h, gnl_entry) {
                 list_del_init(&fcport->gnl_entry);
+                spin_lock(&vha->hw->tgt.sess_lock);
                 fcport->flags &= ~(FCF_ASYNC_SENT | FCF_ASYNC_ACTIVE);
+                spin_unlock(&vha->hw->tgt.sess_lock);
                 ea.fcport = fcport;
 
                 qla2x00_fcport_event_handler(vha, &ea);
         }
+        spin_unlock_irqrestore(&vha->gnl.fcports_lock, flags);
 
+        spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
         /* create new fcport if fw has knowledge of new sessions */
         for (i = 0; i < n; i++) {
                 port_id_t id;
@@ -710,18 +713,21 @@ int qla24xx_async_gnl(struct scsi_qla_host *vha, fc_port_t *fcport)
         ql_dbg(ql_dbg_disc, vha, 0x20d9,
             "Async-gnlist WWPN %8phC \n", fcport->port_name);
 
-        spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
+        spin_lock_irqsave(&vha->gnl.fcports_lock, flags);
+        if (!list_empty(&fcport->gnl_entry)) {
+                spin_unlock_irqrestore(&vha->gnl.fcports_lock, flags);
+                rval = QLA_SUCCESS;
+                goto done;
+        }
+
+        spin_lock(&vha->hw->tgt.sess_lock);
         fcport->disc_state = DSC_GNL;
         fcport->last_rscn_gen = fcport->rscn_gen;
         fcport->last_login_gen = fcport->login_gen;
+        spin_unlock(&vha->hw->tgt.sess_lock);
 
         list_add_tail(&fcport->gnl_entry, &vha->gnl.fcports);
-        if (vha->gnl.sent) {
-                spin_unlock_irqrestore(&vha->hw->tgt.sess_lock, flags);
-                return QLA_SUCCESS;
-        }
-        vha->gnl.sent = 1;
-        spin_unlock_irqrestore(&vha->hw->tgt.sess_lock, flags);
+        spin_unlock_irqrestore(&vha->gnl.fcports_lock, flags);
 
         sp = qla2x00_get_sp(vha, fcport, GFP_KERNEL);
         if (!sp)
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index afcb5567998a..585f37155f29 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -4577,6 +4577,7 @@ struct scsi_qla_host *qla2x00_create_host(struct scsi_host_template *sht,
 
         spin_lock_init(&vha->work_lock);
         spin_lock_init(&vha->cmd_list_lock);
+        spin_lock_init(&vha->gnl.fcports_lock);
         init_waitqueue_head(&vha->fcport_waitQ);
         init_waitqueue_head(&vha->vref_waitq);
 
@@ -4877,6 +4878,8 @@ void qla24xx_create_new_sess(struct scsi_qla_host *vha, struct qla_work_evt *e)
                         }
                         qlt_plogi_ack_unref(vha, pla);
                 } else {
+                        fc_port_t *dfcp = NULL;
+
                         spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
                         tfcp = qla2x00_find_fcport_by_nportid(vha,
                             &e->u.new_sess.id, 1);
@@ -4899,11 +4902,13 @@ void qla24xx_create_new_sess(struct scsi_qla_host *vha, struct qla_work_evt *e)
                                 default:
                                         fcport->login_pause = 1;
                                         tfcp->conflict = fcport;
-                                        qlt_schedule_sess_for_deletion(tfcp);
+                                        dfcp = tfcp;
                                         break;
                                 }
                         }
                         spin_unlock_irqrestore(&vha->hw->tgt.sess_lock, flags);
+                        if (dfcp)
+                                qlt_schedule_sess_for_deletion(tfcp);
 
                         wwn = wwn_to_u64(fcport->node_name);
 
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);