[S390] cio: introduce ccw device todos

Introduce a central mechanism for performing delayed ccw device work
to ensure that different types of work do not overwrite each other.
Prioritization ensures that the most important work is always
performed while less important tasks are either obsoleted or repeated
later.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 100 insertions, 103 deletions

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 0dcfc0ee3d81..167446785d19 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -306,47 +306,6 @@ static void ccw_device_unregister(struct ccw_device *cdev)
         }
 }
 
-static void ccw_device_remove_orphan_cb(struct work_struct *work)
-{
-        struct ccw_device_private *priv;
-        struct ccw_device *cdev;
-
-        priv = container_of(work, struct ccw_device_private, kick_work);
-        cdev = priv->cdev;
-        ccw_device_unregister(cdev);
-        /* Release cdev reference for workqueue processing. */
-        put_device(&cdev->dev);
-}
-
-static void
-ccw_device_remove_disconnected(struct ccw_device *cdev)
-{
-        unsigned long flags;
-
-        /*
-         * Forced offline in disconnected state means
-         * 'throw away device'.
-         */
-        if (ccw_device_is_orphan(cdev)) {
-                /*
-                 * Deregister ccw device.
-                 * Unfortunately, we cannot do this directly from the
-                 * attribute method.
-                 */
-                /* Get cdev reference for workqueue processing. */
-                if (!get_device(&cdev->dev))
-                        return;
-                spin_lock_irqsave(cdev->ccwlock, flags);
-                cdev->private->state = DEV_STATE_NOT_OPER;
-                spin_unlock_irqrestore(cdev->ccwlock, flags);
-                PREPARE_WORK(&cdev->private->kick_work,
-                                ccw_device_remove_orphan_cb);
-                queue_work(slow_path_wq, &cdev->private->kick_work);
-        } else
-                /* Deregister subchannel, which will kill the ccw device. */
-                ccw_device_schedule_sch_unregister(cdev);
-}
-
 /**
  * ccw_device_set_offline() - disable a ccw device for I/O
  * @cdev: target ccw device
@@ -494,9 +453,11 @@ error:
 
 static int online_store_handle_offline(struct ccw_device *cdev)
 {
-        if (cdev->private->state == DEV_STATE_DISCONNECTED)
-                ccw_device_remove_disconnected(cdev);
-        else if (cdev->online && cdev->drv && cdev->drv->set_offline)
+        if (cdev->private->state == DEV_STATE_DISCONNECTED) {
+                spin_lock_irq(cdev->ccwlock);
+                ccw_device_sched_todo(cdev, CDEV_TODO_UNREG_EVAL);
+                spin_unlock_irq(cdev->ccwlock);
+        } else if (cdev->online && cdev->drv && cdev->drv->set_offline)
                 return ccw_device_set_offline(cdev);
         return 0;
 }
@@ -690,17 +651,10 @@ static struct ccw_device *get_ccwdev_by_dev_id(struct ccw_dev_id *dev_id)
         return dev ? to_ccwdev(dev) : NULL;
 }
 
-void ccw_device_do_unbind_bind(struct work_struct *work)
+static void ccw_device_do_unbind_bind(struct ccw_device *cdev)
 {
-        struct ccw_device_private *priv;
-        struct ccw_device *cdev;
-        struct subchannel *sch;
         int ret;
 
-        priv = container_of(work, struct ccw_device_private, kick_work);
-        cdev = priv->cdev;
-        sch = to_subchannel(cdev->dev.parent);
-
         if (test_bit(1, &cdev->private->registered)) {
                 device_release_driver(&cdev->dev);
                 ret = device_attach(&cdev->dev);
@@ -735,6 +689,8 @@ static struct ccw_device * io_subchannel_allocate_dev(struct subchannel *sch)
         return ERR_PTR(-ENOMEM);
 }
 
+static void ccw_device_todo(struct work_struct *work);
+
 static int io_subchannel_initialize_dev(struct subchannel *sch,
                                         struct ccw_device *cdev)
 {
@@ -742,7 +698,7 @@ static int io_subchannel_initialize_dev(struct subchannel *sch,
         atomic_set(&cdev->private->onoff, 0);
         cdev->dev.parent = &sch->dev;
         cdev->dev.release = ccw_device_release;
-        INIT_WORK(&cdev->private->kick_work, NULL);
+        INIT_WORK(&cdev->private->todo_work, ccw_device_todo);
         cdev->dev.groups = ccwdev_attr_groups;
         /* Do first half of device_register. */
         device_initialize(&cdev->dev);
@@ -797,17 +753,12 @@ static void sch_create_and_recog_new_device(struct subchannel *sch)
 /*
  * Register recognized device.
  */
-static void
-io_subchannel_register(struct work_struct *work)
+static void io_subchannel_register(struct ccw_device *cdev)
 {
-        struct ccw_device_private *priv;
-        struct ccw_device *cdev;
         struct subchannel *sch;
         int ret;
         unsigned long flags;
 
-        priv = container_of(work, struct ccw_device_private, kick_work);
-        cdev = priv->cdev;
         sch = to_subchannel(cdev->dev.parent);
         /*
          * Check if subchannel is still registered. It may have become
@@ -859,41 +810,23 @@ out:
         cdev->private->flags.recog_done = 1;
         wake_up(&cdev->private->wait_q);
 out_err:
-        /* Release reference for workqueue processing. */
-        put_device(&cdev->dev);
         if (atomic_dec_and_test(&ccw_device_init_count))
                 wake_up(&ccw_device_init_wq);
 }
 
-static void ccw_device_call_sch_unregister(struct work_struct *work)
+static void ccw_device_call_sch_unregister(struct ccw_device *cdev)
 {
-        struct ccw_device_private *priv;
-        struct ccw_device *cdev;
         struct subchannel *sch;
 
-        priv = container_of(work, struct ccw_device_private, kick_work);
-        cdev = priv->cdev;
         /* Get subchannel reference for local processing. */
         if (!get_device(cdev->dev.parent))
                 return;
         sch = to_subchannel(cdev->dev.parent);
         css_sch_device_unregister(sch);
-        /* Release cdev reference for workqueue processing.*/
-        put_device(&cdev->dev);
         /* Release subchannel reference for local processing. */
         put_device(&sch->dev);
 }
 
-void ccw_device_schedule_sch_unregister(struct ccw_device *cdev)
-{
-        /* Get cdev reference for workqueue processing. */
-        if (!get_device(&cdev->dev))
-                return;
-        PREPARE_WORK(&cdev->private->kick_work,
-                     ccw_device_call_sch_unregister);
-        queue_work(slow_path_wq, &cdev->private->kick_work);
-}
-
 /*
  * subchannel recognition done. Called from the state machine.
  */
@@ -909,7 +842,8 @@ io_subchannel_recog_done(struct ccw_device *cdev)
                 /* Device did not respond in time. */
         case DEV_STATE_NOT_OPER:
                 cdev->private->flags.recog_done = 1;
-                ccw_device_schedule_sch_unregister(cdev);
+                /* Remove device found not operational. */
+                ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
                 if (atomic_dec_and_test(&ccw_device_init_count))
                         wake_up(&ccw_device_init_wq);
                 break;
@@ -918,11 +852,7 @@ io_subchannel_recog_done(struct ccw_device *cdev)
                  * We can't register the device in interrupt context so
                  * we schedule a work item.
                  */
-                if (!get_device(&cdev->dev))
-                        break;
-                PREPARE_WORK(&cdev->private->kick_work,
-                             io_subchannel_register);
-                queue_work(slow_path_wq, &cdev->private->kick_work);
+                ccw_device_sched_todo(cdev, CDEV_TODO_REGISTER);
                 break;
         }
 }
@@ -1333,20 +1263,16 @@ static void ccw_device_schedule_recovery(void)
 static int purge_fn(struct device *dev, void *data)
 {
         struct ccw_device *cdev = to_ccwdev(dev);
-        struct ccw_device_private *priv = cdev->private;
-        int unreg;
+        struct ccw_dev_id *id = &cdev->private->dev_id;
 
         spin_lock_irq(cdev->ccwlock);
-        unreg = is_blacklisted(priv->dev_id.ssid, priv->dev_id.devno) &&
-                (priv->state == DEV_STATE_OFFLINE);
+        if (is_blacklisted(id->ssid, id->devno) &&
+            (cdev->private->state == DEV_STATE_OFFLINE)) {
+                CIO_MSG_EVENT(3, "ccw: purging 0.%x.%04x\n", id->ssid,
+                              id->devno);
+                ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
+        }
         spin_unlock_irq(cdev->ccwlock);
-        if (!unreg)
-                goto out;
-        CIO_MSG_EVENT(3, "ccw: purging 0.%x.%04x\n", priv->dev_id.ssid,
-                      priv->dev_id.devno);
-        ccw_device_schedule_sch_unregister(cdev);
-
-out:
         /* Abort loop in case of pending signal. */
         if (signal_pending(current))
                 return -EINTR;
@@ -1456,12 +1382,14 @@ static int io_subchannel_sch_event(struct subchannel *sch, int process)
                 goto out_unlock;
         if (work_pending(&sch->todo_work))
                 goto out_unlock;
+        cdev = sch_get_cdev(sch);
+        if (cdev && work_pending(&cdev->private->todo_work))
+                goto out_unlock;
         action = sch_get_action(sch);
         CIO_MSG_EVENT(2, "event: sch 0.%x.%04x, process=%d, action=%d\n",
                       sch->schid.ssid, sch->schid.sch_no, process,
                       action);
         /* Perform immediate actions while holding the lock. */
-        cdev = sch_get_cdev(sch);
         switch (action) {
         case IO_SCH_REPROBE:
                 /* Trigger device recognition. */
@@ -1753,7 +1681,7 @@ static int ccw_device_pm_prepare(struct device *dev)
 {
         struct ccw_device *cdev = to_ccwdev(dev);
 
-        if (work_pending(&cdev->private->kick_work))
+        if (work_pending(&cdev->private->todo_work))
                 return -EAGAIN;
         /* Fail while device is being set online/offline. */
         if (atomic_read(&cdev->private->onoff))
@@ -1874,7 +1802,7 @@ static int resume_handle_boxed(struct ccw_device *cdev)
         cdev->private->state = DEV_STATE_BOXED;
         if (ccw_device_notify(cdev, CIO_BOXED))
                 return 0;
-        ccw_device_schedule_sch_unregister(cdev);
+        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
         return -ENODEV;
 }
 
@@ -1883,7 +1811,7 @@ static int resume_handle_disc(struct ccw_device *cdev)
         cdev->private->state = DEV_STATE_DISCONNECTED;
         if (ccw_device_notify(cdev, CIO_GONE))
                 return 0;
-        ccw_device_schedule_sch_unregister(cdev);
+        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG);
         return -ENODEV;
 }
 
@@ -1928,9 +1856,7 @@ static int ccw_device_pm_restore(struct device *dev)
         /* check if the device type has changed */
         if (!ccw_device_test_sense_data(cdev)) {
                 ccw_device_update_sense_data(cdev);
-                PREPARE_WORK(&cdev->private->kick_work,
-                             ccw_device_do_unbind_bind);
-                queue_work(ccw_device_work, &cdev->private->kick_work);
+                ccw_device_sched_todo(cdev, CDEV_TODO_REBIND);
                 ret = -ENODEV;
                 goto out_unlock;
         }
@@ -1974,7 +1900,7 @@ out_disc_unlock:
         goto out_restore;
 
 out_unreg_unlock:
-        ccw_device_schedule_sch_unregister(cdev);
+        ccw_device_sched_todo(cdev, CDEV_TODO_UNREG_EVAL);
         ret = -ENODEV;
 out_unlock:
         spin_unlock_irq(sch->lock);
@@ -2039,6 +1965,77 @@ ccw_device_get_subchannel_id(struct ccw_device *cdev)
         return sch->schid;
 }
 
+static void ccw_device_todo(struct work_struct *work)
+{
+        struct ccw_device_private *priv;
+        struct ccw_device *cdev;
+        struct subchannel *sch;
+        enum cdev_todo todo;
+
+        priv = container_of(work, struct ccw_device_private, todo_work);
+        cdev = priv->cdev;
+        sch = to_subchannel(cdev->dev.parent);
+        /* Find out todo. */
+        spin_lock_irq(cdev->ccwlock);
+        todo = priv->todo;
+        priv->todo = CDEV_TODO_NOTHING;
+        CIO_MSG_EVENT(4, "cdev_todo: cdev=0.%x.%04x todo=%d\n",
+                      priv->dev_id.ssid, priv->dev_id.devno, todo);
+        spin_unlock_irq(cdev->ccwlock);
+        /* Perform todo. */
+        switch (todo) {
+        case CDEV_TODO_ENABLE_CMF:
+                cmf_reenable(cdev);
+                break;
+        case CDEV_TODO_REBIND:
+                ccw_device_do_unbind_bind(cdev);
+                break;
+        case CDEV_TODO_REGISTER:
+                io_subchannel_register(cdev);
+                break;
+        case CDEV_TODO_UNREG_EVAL:
+                if (!sch_is_pseudo_sch(sch))
+                        css_schedule_eval(sch->schid);
+                /* fall-through */
+        case CDEV_TODO_UNREG:
+                if (sch_is_pseudo_sch(sch))
+                        ccw_device_unregister(cdev);
+                else
+                        ccw_device_call_sch_unregister(cdev);
+                break;
+        default:
+                break;
+        }
+        /* Release workqueue ref. */
+        put_device(&cdev->dev);
+}
+
+/**
+ * ccw_device_sched_todo - schedule ccw device operation
+ * @cdev: ccw device
+ * @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 ccwdev lock held.
+ */
+void ccw_device_sched_todo(struct ccw_device *cdev, enum cdev_todo todo)
+{
+        CIO_MSG_EVENT(4, "cdev_todo: sched cdev=0.%x.%04x todo=%d\n",
+                      cdev->private->dev_id.ssid, cdev->private->dev_id.devno,
+                      todo);
+        if (cdev->private->todo >= todo)
+                return;
+        cdev->private->todo = todo;
+        /* Get workqueue ref. */
+        if (!get_device(&cdev->dev))
+                return;
+        if (!queue_work(slow_path_wq, &cdev->private->todo_work)) {
+                /* Already queued, release workqueue ref. */
+                put_device(&cdev->dev);
+        }
+}
+
 MODULE_LICENSE("GPL");
 EXPORT_SYMBOL(ccw_device_set_online);
 EXPORT_SYMBOL(ccw_device_set_offline);