--- zzzz-none-000/linux-3.10.107/drivers/s390/scsi/zfcp_fc.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/s390/scsi/zfcp_fc.c	2021-02-04 17:41:59.000000000 +0000
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/utsname.h>
+#include <linux/random.h>
 #include <scsi/fc/fc_els.h>
 #include <scsi/libfc.h>
 #include "zfcp_ext.h"
@@ -31,12 +32,54 @@
 MODULE_PARM_DESC(no_auto_port_rescan,
 		 "no automatic port_rescan (default off)");
 
+static unsigned int port_scan_backoff = 500;
+module_param(port_scan_backoff, uint, 0600);
+MODULE_PARM_DESC(port_scan_backoff,
+	"upper limit of port scan random backoff in msecs (default 500)");
+
+static unsigned int port_scan_ratelimit = 60000;
+module_param(port_scan_ratelimit, uint, 0600);
+MODULE_PARM_DESC(port_scan_ratelimit,
+	"minimum interval between port scans in msecs (default 60000)");
+
+unsigned int zfcp_fc_port_scan_backoff(void)
+{
+	if (!port_scan_backoff)
+		return 0;
+	return get_random_int() % port_scan_backoff;
+}
+
+static void zfcp_fc_port_scan_time(struct zfcp_adapter *adapter)
+{
+	unsigned long interval = msecs_to_jiffies(port_scan_ratelimit);
+	unsigned long backoff = msecs_to_jiffies(zfcp_fc_port_scan_backoff());
+
+	adapter->next_port_scan = jiffies + interval + backoff;
+}
+
+static void zfcp_fc_port_scan(struct zfcp_adapter *adapter)
+{
+	unsigned long now = jiffies;
+	unsigned long next = adapter->next_port_scan;
+	unsigned long delay = 0, max;
+
+	/* delay only needed within waiting period */
+	if (time_before(now, next)) {
+		delay = next - now;
+		/* paranoia: never ever delay scans longer than specified */
+		max = msecs_to_jiffies(port_scan_ratelimit + port_scan_backoff);
+		delay = min(delay, max);
+	}
+
+	queue_delayed_work(adapter->work_queue, &adapter->scan_work, delay);
+}
+
 void zfcp_fc_conditional_port_scan(struct zfcp_adapter *adapter)
 {
 	if (no_auto_port_rescan)
 		return;
 
-	queue_work(adapter->work_queue, &adapter->scan_work);
+	zfcp_fc_port_scan(adapter);
 }
 
 void zfcp_fc_inverse_conditional_port_scan(struct zfcp_adapter *adapter)
@@ -44,7 +87,7 @@
 	if (!no_auto_port_rescan)
 		return;
 
-	queue_work(adapter->work_queue, &adapter->scan_work);
+	zfcp_fc_port_scan(adapter);
 }
 
 /**
@@ -465,7 +508,7 @@
 	/* port is good, unblock rport without going through erp */
 	zfcp_scsi_schedule_rport_register(port);
  out:
-	atomic_clear_mask(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
+	atomic_andnot(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
 	put_device(&port->dev);
 	kmem_cache_free(zfcp_fc_req_cache, fc_req);
 }
@@ -521,14 +564,14 @@
 	if (atomic_read(&port->status) & ZFCP_STATUS_PORT_LINK_TEST)
 		goto out;
 
-	atomic_set_mask(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
+	atomic_or(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
 
 	retval = zfcp_fc_adisc(port);
 	if (retval == 0)
 		return;
 
 	/* send of ADISC was not possible */
-	atomic_clear_mask(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
+	atomic_andnot(ZFCP_STATUS_PORT_LINK_TEST, &port->status);
 	zfcp_erp_port_forced_reopen(port, 0, "fcltwk1");
 
 out:
@@ -597,7 +640,7 @@
 	if (!(atomic_read(&port->status) & ZFCP_STATUS_COMMON_NOESC))
 		return;
 
-	atomic_clear_mask(ZFCP_STATUS_COMMON_NOESC, &port->status);
+	atomic_andnot(ZFCP_STATUS_COMMON_NOESC, &port->status);
 
 	if ((port->supported_classes != 0) ||
 	    !list_empty(&port->unit_list))
@@ -668,7 +711,7 @@
 
 	list_for_each_entry_safe(port, tmp, &remove_lh, list) {
 		zfcp_erp_port_shutdown(port, 0, "fcegpf2");
-		zfcp_device_unregister(&port->dev, &zfcp_sysfs_port_attrs);
+		device_unregister(&port->dev);
 	}
 
 	return ret;
@@ -680,12 +723,15 @@
  */
 void zfcp_fc_scan_ports(struct work_struct *work)
 {
-	struct zfcp_adapter *adapter = container_of(work, struct zfcp_adapter,
+	struct delayed_work *dw = to_delayed_work(work);
+	struct zfcp_adapter *adapter = container_of(dw, struct zfcp_adapter,
 						    scan_work);
 	int ret, i;
 	struct zfcp_fc_req *fc_req;
 	int chain, max_entries, buf_num, max_bytes;
 
+	zfcp_fc_port_scan_time(adapter);
+
 	chain = adapter->adapter_features & FSF_FEATURE_ELS_CT_CHAINED_SBALS;
 	buf_num = chain ? ZFCP_FC_GPN_FT_NUM_BUFS : 1;
 	max_entries = chain ? ZFCP_FC_GPN_FT_MAX_ENT : ZFCP_FC_GPN_FT_ENT_PAGE;