diff options
Diffstat (limited to 'drivers/s390/scsi/zfcp_fc.c')
| -rw-r--r-- | drivers/s390/scsi/zfcp_fc.c | 52 |
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; |