[S390] hibernate: directly trigger subchannel evaluation

Using the generic css_schedule_eval to evaluate subchannels
while resuming from hibernation is very slow when used with
many devices. Provide a new evaluation trigger which exploits
css_sched_sch_todo and use this in the resume callback for
ccw devices.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 66 insertions, 47 deletions

diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 155a82bcb9e5..4a1ff5c2eb88 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -68,8 +68,13 @@ struct schib {
         __u8 mda[4];             /* model dependent area */
 } __attribute__ ((packed,aligned(4)));
 
+/*
+ * When rescheduled, todo's with higher values will overwrite those
+ * with lower values.
+ */
 enum sch_todo {
         SCH_TODO_NOTHING,
+        SCH_TODO_EVAL,
         SCH_TODO_UNREG,
 };
 
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 92d7324acb1c..21908e67bf67 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -195,51 +195,6 @@ void css_sch_device_unregister(struct subchannel *sch)
 }
 EXPORT_SYMBOL_GPL(css_sch_device_unregister);
 
-static void css_sch_todo(struct work_struct *work)
-{
-        struct subchannel *sch;
-        enum sch_todo todo;
-
-        sch = container_of(work, struct subchannel, todo_work);
-        /* Find out todo. */
-        spin_lock_irq(sch->lock);
-        todo = sch->todo;
-        CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
-                      sch->schid.sch_no, todo);
-        sch->todo = SCH_TODO_NOTHING;
-        spin_unlock_irq(sch->lock);
-        /* Perform todo. */
-        if (todo == SCH_TODO_UNREG)
-                css_sch_device_unregister(sch);
-        /* Release workqueue ref. */
-        put_device(&sch->dev);
-}
-
-/**
- * css_sched_sch_todo - schedule a subchannel operation
- * @sch: subchannel
- * @todo: todo
- *
- * Schedule the operation identified by @todo to be performed on the slow path
- * workqueue. Do nothing if another operation with higher priority is already
- * scheduled. Needs to be called with subchannel lock held.
- */
-void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)
-{
-        CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",
-                      sch->schid.ssid, sch->schid.sch_no, todo);
-        if (sch->todo >= todo)
-                return;
-        /* Get workqueue ref. */
-        if (!get_device(&sch->dev))
-                return;
-        sch->todo = todo;
-        if (!queue_work(cio_work_q, &sch->todo_work)) {
-                /* Already queued, release workqueue ref. */
-                put_device(&sch->dev);
-        }
-}
-
 static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 {
         int i;
@@ -466,6 +421,65 @@ static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
                 css_schedule_eval(schid);
 }
 
+/**
+ * css_sched_sch_todo - schedule a subchannel operation
+ * @sch: subchannel
+ * @todo: todo
+ *
+ * Schedule the operation identified by @todo to be performed on the slow path
+ * workqueue. Do nothing if another operation with higher priority is already
+ * scheduled. Needs to be called with subchannel lock held.
+ */
+void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)
+{
+        CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",
+                      sch->schid.ssid, sch->schid.sch_no, todo);
+        if (sch->todo >= todo)
+                return;
+        /* Get workqueue ref. */
+        if (!get_device(&sch->dev))
+                return;
+        sch->todo = todo;
+        if (!queue_work(cio_work_q, &sch->todo_work)) {
+                /* Already queued, release workqueue ref. */
+                put_device(&sch->dev);
+        }
+}
+
+static void css_sch_todo(struct work_struct *work)
+{
+        struct subchannel *sch;
+        enum sch_todo todo;
+        int ret;
+
+        sch = container_of(work, struct subchannel, todo_work);
+        /* Find out todo. */
+        spin_lock_irq(sch->lock);
+        todo = sch->todo;
+        CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
+                      sch->schid.sch_no, todo);
+        sch->todo = SCH_TODO_NOTHING;
+        spin_unlock_irq(sch->lock);
+        /* Perform todo. */
+        switch (todo) {
+        case SCH_TODO_NOTHING:
+                break;
+        case SCH_TODO_EVAL:
+                ret = css_evaluate_known_subchannel(sch, 1);
+                if (ret == -EAGAIN) {
+                        spin_lock_irq(sch->lock);
+                        css_sched_sch_todo(sch, todo);
+                        spin_unlock_irq(sch->lock);
+                }
+                break;
+        case SCH_TODO_UNREG:
+                css_sch_device_unregister(sch);
+                break;
+        }
+        /* Release workqueue ref. */
+        put_device(&sch->dev);
+}
+
 static struct idset *slow_subchannel_set;
 static spinlock_t slow_subchannel_lock;
 static wait_queue_head_t css_eval_wq;
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index d734f4a0ecac..47269858ecb6 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1868,9 +1868,9 @@ static void __ccw_device_pm_restore(struct ccw_device *cdev)
          */
         cdev->private->flags.resuming = 1;
         cdev->private->path_new_mask = LPM_ANYPATH;
-        css_schedule_eval(sch->schid);
+        css_sched_sch_todo(sch, SCH_TODO_EVAL);
         spin_unlock_irq(sch->lock);
-        css_complete_work();
+        css_wait_for_slow_path();
 
         /* cdev may have been moved to a different subchannel. */
         sch = to_subchannel(cdev->dev.parent);