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path: root/drivers/s390/scsi/zfcp_fc.c
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Diffstat (limited to 'drivers/s390/scsi/zfcp_fc.c')
-rw-r--r--drivers/s390/scsi/zfcp_fc.c52
1 files changed, 49 insertions, 3 deletions
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index ca28e1c66115..25d49f32ca63 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -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_param_named(no_auto_port_rescan, no_auto_port_rescan, bool, 0600);
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 @@ void zfcp_fc_inverse_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);
}
/**
@@ -680,12 +723,15 @@ static int zfcp_fc_eval_gpn_ft(struct zfcp_fc_req *fc_req,
*/
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;