scsi: qla2xxx: Fix slow mem alloc behind lock

Call Trace:
[<ffffffff81341687>] dump_stack+0x6b/0xa4
[<ffffffff810c3e30>] ? print_irqtrace_events+0xd0/0xe0
[<ffffffff8109e3c3>] ___might_sleep+0x183/0x240
[<ffffffff8109e4d2>] __might_sleep+0x52/0x90
[<ffffffff811fe17b>] kmem_cache_alloc_trace+0x5b/0x300
[<ffffffff810c666b>] ? __lock_acquired+0x30b/0x420
[<ffffffffa0733c28>] qla2x00_alloc_fcport+0x38/0x2a0 [qla2xxx]
[<ffffffffa07217f4>] ? qla2x00_do_work+0x34/0x2b0 [qla2xxx]
[<ffffffff816cc82b>] ? _raw_spin_lock_irqsave+0x7b/0x90
[<ffffffffa072169a>] ? qla24xx_create_new_sess+0x3a/0x160 [qla2xxx]
[<ffffffffa0721723>] qla24xx_create_new_sess+0xc3/0x160 [qla2xxx]
[<ffffffff810c91ed>] ? trace_hardirqs_on+0xd/0x10
[<ffffffffa07218f8>] qla2x00_do_work+0x138/0x2b0 [qla2xxx]

Signed-off-by: Quinn Tran <[e-mail]>
Signed-off-by: Himanshu Madhani <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/qla2xxx/qla_gbl.h

···
 extern char qla2x00_version_str[];
 
 extern struct kmem_cache *srb_cachep;
+extern struct kmem_cache *qla_tgt_plogi_cachep;
 
 extern int ql2xlogintimeout;
 extern int qlport_down_retry;

drivers/scsi/qla2xxx/qla_os.c

···
 void qla24xx_create_new_sess(struct scsi_qla_host *vha, struct qla_work_evt *e)
 {
 	unsigned long flags;
-	fc_port_t *fcport =  NULL;
+	fc_port_t *fcport =  NULL, *tfcp;
 	struct qlt_plogi_ack_t *pla =
 	    (struct qlt_plogi_ack_t *)e->u.new_sess.pla;
+	uint8_t free_fcport = 0;
 
 	spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
 	fcport = qla2x00_find_fcport_by_wwpn(vha, e->u.new_sess.port_name, 1);
···
 			pla->ref_count--;
 		}
 	} else {
+		spin_unlock_irqrestore(&vha->hw->tgt.sess_lock, flags);
 		fcport = qla2x00_alloc_fcport(vha, GFP_KERNEL);
 		if (fcport) {
 			fcport->d_id = e->u.new_sess.id;
···
 
 			memcpy(fcport->port_name, e->u.new_sess.port_name,
 			    WWN_SIZE);
+		} else {
+			ql_dbg(ql_dbg_disc, vha, 0xffff,
+				   "%s %8phC mem alloc fail.\n",
+				   __func__, e->u.new_sess.port_name);
+
+			if (pla)
+				kmem_cache_free(qla_tgt_plogi_cachep, pla);
+			return;
+		}
+
+		spin_lock_irqsave(&vha->hw->tgt.sess_lock, flags);
+		/* search again to make sure one else got ahead */
+		tfcp = qla2x00_find_fcport_by_wwpn(vha,
+		    e->u.new_sess.port_name, 1);
+		if (tfcp) {
+			/* should rarily happen */
+			ql_dbg(ql_dbg_disc, vha, 0xffff,
+			    "%s %8phC found existing fcport b4 add. DS %d LS %d\n",
+			    __func__, tfcp->port_name, tfcp->disc_state,
+			    tfcp->fw_login_state);
+
+			free_fcport = 1;
+		} else {
 			list_add_tail(&fcport->list, &vha->vp_fcports);
 
 			if (pla) {
···
 			qlt_plogi_ack_unref(vha, pla);
 		else
 			qla24xx_async_gnl(vha, fcport);
+	}
+
+	if (free_fcport) {
+		qla2x00_free_fcport(fcport);
+		if (pla)
+			kmem_cache_free(qla_tgt_plogi_cachep, pla);
 	}
 }
 

drivers/scsi/qla2xxx/qla_target.c

···
  * Global Variables
  */
 static struct kmem_cache *qla_tgt_mgmt_cmd_cachep;
-static struct kmem_cache *qla_tgt_plogi_cachep;
+struct kmem_cache *qla_tgt_plogi_cachep;
 static mempool_t *qla_tgt_mgmt_cmd_mempool;
 static struct workqueue_struct *qla_tgt_wq;
 static DEFINE_MUTEX(qla_tgt_mutex);