[S390] cio: replace subchannel evaluation queue with bitmap

Use a bitmap for indicating which subchannels require evaluation
instead of allocating memory for each evaluation request. This
approach reduces memory consumption during recovery in case of
massive evaluation request occurrence and removes the need for
memory allocation failure handling.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 33 insertions, 97 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index 02615eb43984..89a130a62654 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -195,12 +195,8 @@ static void terminate_internal_io(struct subchannel *sch)
         if (cio_clear(sch)) {
                 /* Recheck device in case clear failed. */
                 sch->lpm = 0;
-                if (device_trigger_verify(sch) != 0) {
-                        if(css_enqueue_subchannel_slow(sch->schid)) {
-                                css_clear_subchannel_slow_list();
-                                need_rescan = 1;
-                        }
-                }
+                if (device_trigger_verify(sch) != 0)
+                        css_schedule_eval(sch->schid);
                 return;
         }
         /* Request retry of internal operation. */
@@ -262,11 +258,8 @@ s390_subchannel_remove_chpid(struct device *dev, void *data)
 
 out_unreg:
         sch->lpm = 0;
-        if (css_enqueue_subchannel_slow(sch->schid)) {
-                css_clear_subchannel_slow_list();
-                need_rescan = 1;
-        }
         spin_unlock_irq(sch->lock);
+        css_schedule_eval(sch->schid);
         return 0;
 }
 
@@ -281,9 +274,6 @@ void chsc_chp_offline(struct chp_id chpid)
                 return;
         bus_for_each_dev(&css_bus_type, NULL, &chpid,
                          s390_subchannel_remove_chpid);
-
-        if (need_rescan || css_slow_subchannels_exist())
-                queue_work(slow_path_wq, &slow_path_work);
 }
 
 struct res_acc_data {
@@ -331,7 +321,6 @@ static int
 s390_process_res_acc_new_sch(struct subchannel_id schid)
 {
         struct schib schib;
-        int ret;
         /*
          * We don't know the device yet, but since a path
          * may be available now to the device we'll have
@@ -342,15 +331,10 @@ s390_process_res_acc_new_sch(struct subchannel_id schid)
          */
         if (stsch_err(schid, &schib))
                 /* We're through */
-                return need_rescan ? -EAGAIN : -ENXIO;
+                return -ENXIO;
 
         /* Put it on the slow path. */
-        ret = css_enqueue_subchannel_slow(schid);
-        if (ret) {
-                css_clear_subchannel_slow_list();
-                need_rescan = 1;
-                return -EAGAIN;
-        }
+        css_schedule_eval(schid);
         return 0;
 }
 
@@ -392,10 +376,8 @@ __s390_process_res_acc(struct subchannel_id schid, void *data)
 }
 
 
-static int
-s390_process_res_acc (struct res_acc_data *res_data)
+static void s390_process_res_acc (struct res_acc_data *res_data)
 {
-        int rc;
         char dbf_txt[15];
 
         sprintf(dbf_txt, "accpr%x.%02x", res_data->chpid.cssid,
@@ -413,12 +395,7 @@ s390_process_res_acc (struct res_acc_data *res_data)
          * The more information we have (info), the less scanning
          * will we have to do.
          */
-        rc = for_each_subchannel(__s390_process_res_acc, res_data);
-        if (css_slow_subchannels_exist())
-                rc = -EAGAIN;
-        else if (rc != -EAGAIN)
-                rc = 0;
-        return rc;
+        for_each_subchannel(__s390_process_res_acc, res_data);
 }
 
 static int
@@ -470,7 +447,7 @@ struct chsc_sei_area {
         /* ccdf has to be big enough for a link-incident record */
 } __attribute__ ((packed));
 
-static int chsc_process_sei_link_incident(struct chsc_sei_area *sei_area)
+static void chsc_process_sei_link_incident(struct chsc_sei_area *sei_area)
 {
         struct chp_id chpid;
         int id;
@@ -478,7 +455,7 @@ static int chsc_process_sei_link_incident(struct chsc_sei_area *sei_area)
         CIO_CRW_EVENT(4, "chsc: link incident (rs=%02x, rs_id=%04x)\n",
                       sei_area->rs, sei_area->rsid);
         if (sei_area->rs != 4)
-                return 0;
+                return;
         id = __get_chpid_from_lir(sei_area->ccdf);
         if (id < 0)
                 CIO_CRW_EVENT(4, "chsc: link incident - invalid LIR\n");
@@ -487,21 +464,18 @@ static int chsc_process_sei_link_incident(struct chsc_sei_area *sei_area)
                 chpid.id = id;
                 chsc_chp_offline(chpid);
         }
-
-        return 0;
 }
 
-static int chsc_process_sei_res_acc(struct chsc_sei_area *sei_area)
+static void chsc_process_sei_res_acc(struct chsc_sei_area *sei_area)
 {
         struct res_acc_data res_data;
         struct chp_id chpid;
         int status;
-        int rc;
 
         CIO_CRW_EVENT(4, "chsc: resource accessibility event (rs=%02x, "
                       "rs_id=%04x)\n", sei_area->rs, sei_area->rsid);
         if (sei_area->rs != 4)
-                return 0;
+                return;
         chp_id_init(&chpid);
         chpid.id = sei_area->rsid;
         /* allocate a new channel path structure, if needed */
@@ -509,7 +483,7 @@ static int chsc_process_sei_res_acc(struct chsc_sei_area *sei_area)
         if (status < 0)
                 chp_new(chpid);
         else if (!status)
-                return 0;
+                return;
         memset(&res_data, 0, sizeof(struct res_acc_data));
         res_data.chpid = chpid;
         if ((sei_area->vf & 0xc0) != 0) {
@@ -521,9 +495,7 @@ static int chsc_process_sei_res_acc(struct chsc_sei_area *sei_area)
                         /* link address */
                         res_data.fla_mask = 0xff00;
         }
-        rc = s390_process_res_acc(&res_data);
-
-        return rc;
+        s390_process_res_acc(&res_data);
 }
 
 struct chp_config_data {
@@ -532,7 +504,7 @@ struct chp_config_data {
         u8 pc;
 };
 
-static int chsc_process_sei_chp_config(struct chsc_sei_area *sei_area)
+static void chsc_process_sei_chp_config(struct chsc_sei_area *sei_area)
 {
         struct chp_config_data *data;
         struct chp_id chpid;
@@ -540,7 +512,7 @@ static int chsc_process_sei_chp_config(struct chsc_sei_area *sei_area)
 
         CIO_CRW_EVENT(4, "chsc: channel-path-configuration notification\n");
         if (sei_area->rs != 0)
-                return 0;
+                return;
         data = (struct chp_config_data *) &(sei_area->ccdf);
         chp_id_init(&chpid);
         for (num = 0; num <= __MAX_CHPID; num++) {
@@ -561,52 +533,44 @@ static int chsc_process_sei_chp_config(struct chsc_sei_area *sei_area)
                         break;
                 }
         }
-
-        return 0;
 }
 
-static int chsc_process_sei(struct chsc_sei_area *sei_area)
+static void chsc_process_sei(struct chsc_sei_area *sei_area)
 {
-        int rc;
-
         /* Check if we might have lost some information. */
-        if (sei_area->flags & 0x40)
+        if (sei_area->flags & 0x40) {
                 CIO_CRW_EVENT(2, "chsc: event overflow\n");
+                css_schedule_eval_all();
+        }
         /* which kind of information was stored? */
-        rc = 0;
         switch (sei_area->cc) {
         case 1: /* link incident*/
-                rc = chsc_process_sei_link_incident(sei_area);
+                chsc_process_sei_link_incident(sei_area);
                 break;
         case 2: /* i/o resource accessibiliy */
-                rc = chsc_process_sei_res_acc(sei_area);
+                chsc_process_sei_res_acc(sei_area);
                 break;
         case 8: /* channel-path-configuration notification */
-                rc = chsc_process_sei_chp_config(sei_area);
+                chsc_process_sei_chp_config(sei_area);
                 break;
         default: /* other stuff */
                 CIO_CRW_EVENT(4, "chsc: unhandled sei content code %d\n",
                               sei_area->cc);
                 break;
         }
-
-        return rc;
 }
 
-int chsc_process_crw(void)
+void chsc_process_crw(void)
 {
         struct chsc_sei_area *sei_area;
-        int ret;
-        int rc;
 
         if (!sei_page)
-                return 0;
+                return;
         /* Access to sei_page is serialized through machine check handler
          * thread, so no need for locking. */
         sei_area = sei_page;
 
         CIO_TRACE_EVENT( 2, "prcss");
-        ret = 0;
         do {
                 memset(sei_area, 0, sizeof(*sei_area));
                 sei_area->request.length = 0x0010;
@@ -616,37 +580,26 @@ int chsc_process_crw(void)
 
                 if (sei_area->response.code == 0x0001) {
                         CIO_CRW_EVENT(4, "chsc: sei successful\n");
-                        rc = chsc_process_sei(sei_area);
-                        if (rc)
-                                ret = rc;
+                        chsc_process_sei(sei_area);
                 } else {
                         CIO_CRW_EVENT(2, "chsc: sei failed (rc=%04x)\n",
                                       sei_area->response.code);
-                        ret = 0;
                         break;
                 }
         } while (sei_area->flags & 0x80);
-
-        return ret;
 }
 
 static int
 __chp_add_new_sch(struct subchannel_id schid)
 {
         struct schib schib;
-        int ret;
 
         if (stsch_err(schid, &schib))
                 /* We're through */
-                return need_rescan ? -EAGAIN : -ENXIO;
+                return -ENXIO;
 
         /* Put it on the slow path. */
-        ret = css_enqueue_subchannel_slow(schid);
-        if (ret) {
-                css_clear_subchannel_slow_list();
-                need_rescan = 1;
-                return -EAGAIN;
-        }
+        css_schedule_eval(schid);
         return 0;
 }
 
@@ -693,22 +646,15 @@ __chp_add(struct subchannel_id schid, void *data)
         return 0;
 }
 
-int chsc_chp_online(struct chp_id chpid)
+void chsc_chp_online(struct chp_id chpid)
 {
-        int rc;
         char dbf_txt[15];
 
         sprintf(dbf_txt, "cadd%x.%02x", chpid.cssid, chpid.id);
         CIO_TRACE_EVENT(2, dbf_txt);
 
-        if (chp_get_status(chpid) == 0)
-                return 0;
-        rc = for_each_subchannel(__chp_add, &chpid);
-        if (css_slow_subchannels_exist())
-                rc = -EAGAIN;
-        if (rc != -EAGAIN)
-                rc = 0;
-        return rc;
+        if (chp_get_status(chpid) != 0)
+                for_each_subchannel(__chp_add, &chpid);
 }
 
 static void __s390_subchannel_vary_chpid(struct subchannel *sch,
@@ -749,12 +695,8 @@ static void __s390_subchannel_vary_chpid(struct subchannel *sch,
                                         sch->driver->verify(&sch->dev);
                         }
                 } else if (!sch->lpm) {
-                        if (device_trigger_verify(sch) != 0) {
-                                if (css_enqueue_subchannel_slow(sch->schid)) {
-                                        css_clear_subchannel_slow_list();
-                                        need_rescan = 1;
-                                }
-                        }
+                        if (device_trigger_verify(sch) != 0)
+                                css_schedule_eval(sch->schid);
                 } else if (sch->driver && sch->driver->verify)
                         sch->driver->verify(&sch->dev);
                 break;
@@ -801,11 +743,7 @@ __s390_vary_chpid_on(struct subchannel_id schid, void *data)
                 /* We're through */
                 return -ENXIO;
         /* Put it on the slow path. */
-        if (css_enqueue_subchannel_slow(schid)) {
-                css_clear_subchannel_slow_list();
-                need_rescan = 1;
-                return -EAGAIN;
-        }
+        css_schedule_eval(schid);
         return 0;
 }
 
@@ -826,8 +764,6 @@ int chsc_chp_vary(struct chp_id chpid, int on)
         if (on)
                 /* Scan for new devices on varied on path. */
                 for_each_subchannel(__s390_vary_chpid_on, NULL);
-        if (need_rescan || css_slow_subchannels_exist())
-                queue_work(slow_path_wq, &slow_path_work);
         return 0;
 }