[S390] Support for disconnected devices reappearing on another subchannel.

- create a 'pseudo_subchannel' per channel subsystem (the 'orphanage')
- use the orphanage as a shelter for ccw_devices that can't remain on the same
  subchannel

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

7 files changed, 296 insertions, 59 deletions

diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index e8d331493fd8..7835a714a405 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -415,6 +415,8 @@ cio_enable_subchannel (struct subchannel *sch, unsigned int isc)
         CIO_TRACE_EVENT (2, "ensch");
         CIO_TRACE_EVENT (2, sch->dev.bus_id);
 
+        if (sch_is_pseudo_sch(sch))
+                return -EINVAL;
         ccode = stsch (sch->schid, &sch->schib);
         if (ccode)
                 return -ENODEV;
@@ -462,6 +464,8 @@ cio_disable_subchannel (struct subchannel *sch)
         CIO_TRACE_EVENT (2, "dissch");
         CIO_TRACE_EVENT (2, sch->dev.bus_id);
 
+        if (sch_is_pseudo_sch(sch))
+                return 0;
         ccode = stsch (sch->schid, &sch->schib);
         if (ccode == 3)         /* Not operational. */
                 return -ENODEV;
@@ -496,7 +500,7 @@ cio_disable_subchannel (struct subchannel *sch)
         return ret;
 }
 
-static int cio_create_sch_lock(struct subchannel *sch)
+int cio_create_sch_lock(struct subchannel *sch)
 {
         sch->lock = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
         if (!sch->lock)
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 7e7369b21a93..35154a210357 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -131,6 +131,8 @@ extern int cio_set_options (struct subchannel *, int);
 extern int cio_get_options (struct subchannel *);
 extern int cio_modify (struct subchannel *);
 
+int cio_create_sch_lock(struct subchannel *);
+
 /* Use with care. */
 #ifdef CONFIG_CCW_CONSOLE
 extern struct subchannel *cio_probe_console(void);
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 65939e2eb415..0bf716619378 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -580,12 +580,24 @@ css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 
-static inline void __init
-setup_css(int nr)
+static inline int __init setup_css(int nr)
 {
         u32 tod_high;
+        int ret;
 
         memset(css[nr], 0, sizeof(struct channel_subsystem));
+        css[nr]->pseudo_subchannel =
+                kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
+        if (!css[nr]->pseudo_subchannel)
+                return -ENOMEM;
+        css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
+        css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
+        sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
+        ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
+        if (ret) {
+                kfree(css[nr]->pseudo_subchannel);
+                return ret;
+        }
         mutex_init(&css[nr]->mutex);
         css[nr]->valid = 1;
         css[nr]->cssid = nr;
@@ -593,6 +605,7 @@ setup_css(int nr)
         css[nr]->device.release = channel_subsystem_release;
         tod_high = (u32) (get_clock() >> 32);
         css_generate_pgid(css[nr], tod_high);
+        return 0;
 }
 
 /*
@@ -629,10 +642,12 @@ init_channel_subsystem (void)
                         ret = -ENOMEM;
                         goto out_unregister;
                 }
-                setup_css(i);
-                ret = device_register(&css[i]->device);
+                ret = setup_css(i);
                 if (ret)
                         goto out_free;
+                ret = device_register(&css[i]->device);
+                if (ret)
+                        goto out_free_all;
                 if (css_characteristics_avail &&
                     css_chsc_characteristics.secm) {
                         ret = device_create_file(&css[i]->device,
@@ -640,6 +655,9 @@ init_channel_subsystem (void)
                         if (ret)
                                 goto out_device;
                 }
+                ret = device_register(&css[i]->pseudo_subchannel->dev);
+                if (ret)
+                        goto out_file;
         }
         css_init_done = 1;
 
@@ -647,13 +665,19 @@ init_channel_subsystem (void)
 
         for_each_subchannel(__init_channel_subsystem, NULL);
         return 0;
+out_file:
+        device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 out_device:
         device_unregister(&css[i]->device);
+out_free_all:
+        kfree(css[i]->pseudo_subchannel->lock);
+        kfree(css[i]->pseudo_subchannel);
 out_free:
         kfree(css[i]);
 out_unregister:
         while (i > 0) {
                 i--;
+                device_unregister(&css[i]->pseudo_subchannel->dev);
                 if (css_characteristics_avail && css_chsc_characteristics.secm)
                         device_remove_file(&css[i]->device,
                                            &dev_attr_cm_enable);
@@ -665,6 +689,11 @@ out:
         return ret;
 }
 
+int sch_is_pseudo_sch(struct subchannel *sch)
+{
+        return sch == to_css(sch->dev.parent)->pseudo_subchannel;
+}
+
 /*
  * find a driver for a subchannel. They identify by the subchannel
  * type with the exception that the console subchannel driver has its own
diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index ac845c1ebf83..71fe380f86f6 100644
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -160,6 +160,8 @@ struct channel_subsystem {
         int cm_enabled;
         void *cub_addr1;
         void *cub_addr2;
+        /* for orphaned ccw devices */
+        struct subchannel *pseudo_subchannel;
 };
 #define to_css(dev) container_of(dev, struct channel_subsystem, device)
 
@@ -187,6 +189,8 @@ void css_clear_subchannel_slow_list(void);
 int css_slow_subchannels_exist(void);
 extern int need_rescan;
 
+int sch_is_pseudo_sch(struct subchannel *);
+
 extern struct workqueue_struct *slow_path_wq;
 extern struct work_struct slow_path_work;
 
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 9a31239fe028..7fe1ccdc7812 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -23,6 +23,7 @@
 #include <asm/param.h>          /* HZ */
 
 #include "cio.h"
+#include "cio_debug.h"
 #include "css.h"
 #include "device.h"
 #include "ioasm.h"
@@ -294,6 +295,11 @@ online_show (struct device *dev, struct device_attribute *attr, char *buf)
         return sprintf(buf, cdev->online ? "1\n" : "0\n");
 }
 
+int ccw_device_is_orphan(struct ccw_device *cdev)
+{
+        return sch_is_pseudo_sch(to_subchannel(cdev->dev.parent));
+}
+
 static void ccw_device_unregister(struct work_struct *work)
 {
         struct ccw_device_private *priv;
@@ -310,10 +316,23 @@ static void
 ccw_device_remove_disconnected(struct ccw_device *cdev)
 {
         struct subchannel *sch;
+        unsigned long flags;
         /*
          * Forced offline in disconnected state means
          * 'throw away device'.
          */
+        if (ccw_device_is_orphan(cdev)) {
+                /* Deregister ccw device. */
+                spin_lock_irqsave(cdev->ccwlock, flags);
+                cdev->private->state = DEV_STATE_NOT_OPER;
+                spin_unlock_irqrestore(cdev->ccwlock, flags);
+                if (get_device(&cdev->dev)) {
+                        PREPARE_WORK(&cdev->private->kick_work,
+                                     ccw_device_unregister);
+                        queue_work(ccw_device_work, &cdev->private->kick_work);
+                }
+                return ;
+        }
         sch = to_subchannel(cdev->dev.parent);
         css_sch_device_unregister(sch);
         /* Reset intparm to zeroes. */
@@ -474,6 +493,8 @@ available_show (struct device *dev, struct device_attribute *attr, char *buf)
         struct ccw_device *cdev = to_ccwdev(dev);
         struct subchannel *sch;
 
+        if (ccw_device_is_orphan(cdev))
+                return sprintf(buf, "no device\n");
         switch (cdev->private->state) {
         case DEV_STATE_BOXED:
                 return sprintf(buf, "boxed\n");
@@ -574,11 +595,10 @@ match_devno(struct device * dev, void * data)
 
         cdev = to_ccwdev(dev);
         if ((cdev->private->state == DEV_STATE_DISCONNECTED) &&
+            !ccw_device_is_orphan(cdev) &&
             ccw_dev_id_is_equal(&cdev->private->dev_id, &d->dev_id) &&
-            (cdev != d->sibling)) {
-                cdev->private->state = DEV_STATE_NOT_OPER;
+            (cdev != d->sibling))
                 return 1;
-        }
         return 0;
 }
 
@@ -595,6 +615,28 @@ static struct ccw_device * get_disc_ccwdev_by_dev_id(struct ccw_dev_id *dev_id,
         return dev ? to_ccwdev(dev) : NULL;
 }
 
+static int match_orphan(struct device *dev, void *data)
+{
+        struct ccw_dev_id *dev_id;
+        struct ccw_device *cdev;
+
+        dev_id = data;
+        cdev = to_ccwdev(dev);
+        return ccw_dev_id_is_equal(&cdev->private->dev_id, dev_id);
+}
+
+static struct ccw_device *
+get_orphaned_ccwdev_by_dev_id(struct channel_subsystem *css,
+                              struct ccw_dev_id *dev_id)
+{
+        struct device *dev;
+
+        dev = device_find_child(&css->pseudo_subchannel->dev, dev_id,
+                                match_orphan);
+
+        return dev ? to_ccwdev(dev) : NULL;
+}
+
 static void
 ccw_device_add_changed(struct work_struct *work)
 {
@@ -614,64 +656,19 @@ ccw_device_add_changed(struct work_struct *work)
         }
 }
 
-extern int css_get_ssd_info(struct subchannel *sch);
-
-void
-ccw_device_do_unreg_rereg(struct work_struct *work)
+void ccw_device_do_unreg_rereg(struct work_struct *work)
 {
         struct ccw_device_private *priv;
         struct ccw_device *cdev;
         struct subchannel *sch;
-        int need_rename;
 
         priv = container_of(work, struct ccw_device_private, kick_work);
         cdev = priv->cdev;
         sch = to_subchannel(cdev->dev.parent);
-        if (cdev->private->dev_id.devno != sch->schib.pmcw.dev) {
-                /*
-                 * The device number has changed. This is usually only when
-                 * a device has been detached under VM and then re-appeared
-                 * on another subchannel because of a different attachment
-                 * order than before. Ideally, we should should just switch
-                 * subchannels, but unfortunately, this is not possible with
-                 * the current implementation.
-                 * Instead, we search for the old subchannel for this device
-                 * number and deregister so there are no collisions with the
-                 * newly registered ccw_device.
-                 * FIXME: Find another solution so the block layer doesn't
-                 *        get possibly sick...
-                 */
-                struct ccw_device *other_cdev;
-                struct ccw_dev_id dev_id;
-
-                need_rename = 1;
-                dev_id.devno = sch->schib.pmcw.dev;
-                dev_id.ssid = sch->schid.ssid;
-                other_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
-                if (other_cdev) {
-                        struct subchannel *other_sch;
-
-                        other_sch = to_subchannel(other_cdev->dev.parent);
-                        if (get_device(&other_sch->dev)) {
-                                stsch(other_sch->schid, &other_sch->schib);
-                                if (other_sch->schib.pmcw.dnv) {
-                                        other_sch->schib.pmcw.intparm = 0;
-                                        cio_modify(other_sch);
-                                }
-                                css_sch_device_unregister(other_sch);
-                        }
-                }
-                /* Update ssd info here. */
-                css_get_ssd_info(sch);
-                cdev->private->dev_id.devno = sch->schib.pmcw.dev;
-        } else
-                need_rename = 0;
+
         device_remove_files(&cdev->dev);
         if (test_and_clear_bit(1, &cdev->private->registered))
                 device_del(&cdev->dev);
-        if (need_rename)
-                snprintf (cdev->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x",
-                          sch->schid.ssid, sch->schib.pmcw.dev);
         PREPARE_WORK(&cdev->private->kick_work,
                      ccw_device_add_changed);
         queue_work(ccw_device_work, &cdev->private->kick_work);
@@ -736,6 +733,131 @@ static struct ccw_device * io_subchannel_create_ccwdev(struct subchannel *sch)
         return cdev;
 }
 
+static int io_subchannel_recog(struct ccw_device *, struct subchannel *);
+
+static void sch_attach_device(struct subchannel *sch,
+                              struct ccw_device *cdev)
+{
+        spin_lock_irq(sch->lock);
+        sch->dev.driver_data = cdev;
+        cdev->private->schid = sch->schid;
+        cdev->ccwlock = sch->lock;
+        device_trigger_reprobe(sch);
+        spin_unlock_irq(sch->lock);
+}
+
+static void sch_attach_disconnected_device(struct subchannel *sch,
+                                           struct ccw_device *cdev)
+{
+        struct subchannel *other_sch;
+        int ret;
+
+        other_sch = to_subchannel(get_device(cdev->dev.parent));
+        ret = device_move(&cdev->dev, &sch->dev);
+        if (ret) {
+                CIO_MSG_EVENT(2, "Moving disconnected device 0.%x.%04x failed "
+                              "(ret=%d)!\n", cdev->private->dev_id.ssid,
+                              cdev->private->dev_id.devno, ret);
+                put_device(&other_sch->dev);
+                return;
+        }
+        other_sch->dev.driver_data = NULL;
+        /* No need to keep a subchannel without ccw device around. */
+        css_sch_device_unregister(other_sch);
+        put_device(&other_sch->dev);
+        sch_attach_device(sch, cdev);
+}
+
+static void sch_attach_orphaned_device(struct subchannel *sch,
+                                       struct ccw_device *cdev)
+{
+        int ret;
+
+        /* Try to move the ccw device to its new subchannel. */
+        ret = device_move(&cdev->dev, &sch->dev);
+        if (ret) {
+                CIO_MSG_EVENT(0, "Moving device 0.%x.%04x from orphanage "
+                              "failed (ret=%d)!\n",
+                              cdev->private->dev_id.ssid,
+                              cdev->private->dev_id.devno, ret);
+                return;
+        }
+        sch_attach_device(sch, cdev);
+}
+
+static void sch_create_and_recog_new_device(struct subchannel *sch)
+{
+        struct ccw_device *cdev;
+
+        /* Need to allocate a new ccw device. */
+        cdev = io_subchannel_create_ccwdev(sch);
+        if (IS_ERR(cdev)) {
+                /* OK, we did everything we could... */
+                css_sch_device_unregister(sch);
+                return;
+        }
+        spin_lock_irq(sch->lock);
+        sch->dev.driver_data = cdev;
+        spin_unlock_irq(sch->lock);
+        /* Start recognition for the new ccw device. */
+        if (io_subchannel_recog(cdev, sch)) {
+                spin_lock_irq(sch->lock);
+                sch->dev.driver_data = NULL;
+                spin_unlock_irq(sch->lock);
+                if (cdev->dev.release)
+                        cdev->dev.release(&cdev->dev);
+                css_sch_device_unregister(sch);
+        }
+}
+
+
+void ccw_device_move_to_orphanage(struct work_struct *work)
+{
+        struct ccw_device_private *priv;
+        struct ccw_device *cdev;
+        struct ccw_device *replacing_cdev;
+        struct subchannel *sch;
+        int ret;
+        struct channel_subsystem *css;
+        struct ccw_dev_id dev_id;
+
+        priv = container_of(work, struct ccw_device_private, kick_work);
+        cdev = priv->cdev;
+        sch = to_subchannel(cdev->dev.parent);
+        css = to_css(sch->dev.parent);
+        dev_id.devno = sch->schib.pmcw.dev;
+        dev_id.ssid = sch->schid.ssid;
+
+        /*
+         * Move the orphaned ccw device to the orphanage so the replacing
+         * ccw device can take its place on the subchannel.
+         */
+        ret = device_move(&cdev->dev, &css->pseudo_subchannel->dev);
+        if (ret) {
+                CIO_MSG_EVENT(0, "Moving device 0.%x.%04x to orphanage failed "
+                              "(ret=%d)!\n", cdev->private->dev_id.ssid,
+                              cdev->private->dev_id.devno, ret);
+                return;
+        }
+        cdev->ccwlock = css->pseudo_subchannel->lock;
+        /*
+         * Search for the replacing ccw device
+         * - among the disconnected devices
+         * - in the orphanage
+         */
+        replacing_cdev = get_disc_ccwdev_by_dev_id(&dev_id, cdev);
+        if (replacing_cdev) {
+                sch_attach_disconnected_device(sch, replacing_cdev);
+                return;
+        }
+        replacing_cdev = get_orphaned_ccwdev_by_dev_id(css, &dev_id);
+        if (replacing_cdev) {
+                sch_attach_orphaned_device(sch, replacing_cdev);
+                return;
+        }
+        sch_create_and_recog_new_device(sch);
+}
+
 /*
  * Register recognized device.
  */
@@ -890,12 +1012,55 @@ io_subchannel_recog(struct ccw_device *cdev, struct subchannel *sch)
         return rc;
 }
 
+static void ccw_device_move_to_sch(struct work_struct *work)
+{
+        struct ccw_device_private *priv;
+        int rc;
+        struct subchannel *sch;
+        struct ccw_device *cdev;
+        struct subchannel *former_parent;
+
+        priv = container_of(work, struct ccw_device_private, kick_work);
+        sch = priv->sch;
+        cdev = priv->cdev;
+        former_parent = ccw_device_is_orphan(cdev) ?
+                NULL : to_subchannel(get_device(cdev->dev.parent));
+        mutex_lock(&sch->reg_mutex);
+        /* Try to move the ccw device to its new subchannel. */
+        rc = device_move(&cdev->dev, &sch->dev);
+        mutex_unlock(&sch->reg_mutex);
+        if (rc) {
+                CIO_MSG_EVENT(2, "Moving device 0.%x.%04x to subchannel "
+                              "0.%x.%04x failed (ret=%d)!\n",
+                              cdev->private->dev_id.ssid,
+                              cdev->private->dev_id.devno, sch->schid.ssid,
+                              sch->schid.sch_no, rc);
+                css_sch_device_unregister(sch);
+                goto out;
+        }
+        if (former_parent) {
+                spin_lock_irq(former_parent->lock);
+                former_parent->dev.driver_data = NULL;
+                spin_unlock_irq(former_parent->lock);
+                css_sch_device_unregister(former_parent);
+                /* Reset intparm to zeroes. */
+                former_parent->schib.pmcw.intparm = 0;
+                cio_modify(former_parent);
+        }
+        sch_attach_device(sch, cdev);
+out:
+        if (former_parent)
+                put_device(&former_parent->dev);
+        put_device(&cdev->dev);
+}
+
 static int
 io_subchannel_probe (struct subchannel *sch)
 {
         struct ccw_device *cdev;
         int rc;
         unsigned long flags;
+        struct ccw_dev_id dev_id;
 
         if (sch->dev.driver_data) {
                 /*
@@ -918,6 +1083,28 @@ io_subchannel_probe (struct subchannel *sch)
                         get_device(&cdev->dev);
                 return 0;
         }
+        /*
+         * First check if a fitting device may be found amongst the
+         * disconnected devices or in the orphanage.
+         */
+        dev_id.devno = sch->schib.pmcw.dev;
+        dev_id.ssid = sch->schid.ssid;
+        cdev = get_disc_ccwdev_by_dev_id(&dev_id, NULL);
+        if (!cdev)
+                cdev = get_orphaned_ccwdev_by_dev_id(to_css(sch->dev.parent),
+                                                     &dev_id);
+        if (cdev) {
+                /*
+                 * Schedule moving the device until when we have a registered
+                 * subchannel to move to and succeed the probe. We can
+                 * unregister later again, when the probe is through.
+                 */
+                cdev->private->sch = sch;
+                PREPARE_WORK(&cdev->private->kick_work,
+                             ccw_device_move_to_sch);
+                queue_work(slow_path_wq, &cdev->private->kick_work);
+                return 0;
+        }
         cdev = io_subchannel_create_ccwdev(sch);
         if (IS_ERR(cdev))
                 return PTR_ERR(cdev);
diff --git a/drivers/s390/cio/device.h b/drivers/s390/cio/device.h
index d5fe95e04cfe..29db6341d632 100644
--- a/drivers/s390/cio/device.h
+++ b/drivers/s390/cio/device.h
@@ -80,6 +80,8 @@ int ccw_device_cancel_halt_clear(struct ccw_device *);
 
 void ccw_device_do_unreg_rereg(struct work_struct *);
 void ccw_device_call_sch_unregister(struct work_struct *);
+void ccw_device_move_to_orphanage(struct work_struct *);
+int ccw_device_is_orphan(struct ccw_device *);
 
 int ccw_device_recognition(struct ccw_device *);
 int ccw_device_online(struct ccw_device *);
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index a487fb0e7d3d..eed14572fc3b 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -186,13 +186,12 @@ ccw_device_handle_oper(struct ccw_device *cdev)
         /*
          * Check if cu type and device type still match. If
          * not, it is certainly another device and we have to
-         * de- and re-register. Also check here for non-matching devno.
+         * de- and re-register.
          */
         if (cdev->id.cu_type != cdev->private->senseid.cu_type ||
             cdev->id.cu_model != cdev->private->senseid.cu_model ||
             cdev->id.dev_type != cdev->private->senseid.dev_type ||
-            cdev->id.dev_model != cdev->private->senseid.dev_model ||
-            cdev->private->dev_id.devno != sch->schib.pmcw.dev) {
+            cdev->id.dev_model != cdev->private->senseid.dev_model) {
                 PREPARE_WORK(&cdev->private->kick_work,
                              ccw_device_do_unreg_rereg);
                 queue_work(ccw_device_work, &cdev->private->kick_work);
@@ -676,6 +675,10 @@ ccw_device_offline(struct ccw_device *cdev)
 {
         struct subchannel *sch;
 
+        if (ccw_device_is_orphan(cdev)) {
+                ccw_device_done(cdev, DEV_STATE_OFFLINE);
+                return 0;
+        }
         sch = to_subchannel(cdev->dev.parent);
         if (stsch(sch->schid, &sch->schib) || !sch->schib.pmcw.dnv)
                 return -ENODEV;
@@ -1121,7 +1124,13 @@ device_trigger_reprobe(struct subchannel *sch)
                 sch->schib.pmcw.mp = 1;
         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
         /* We should also udate ssd info, but this has to wait. */
-        ccw_device_start_id(cdev, 0);
+        /* Check if this is another device which appeared on the same sch. */
+        if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {
+                PREPARE_WORK(&cdev->private->kick_work,
+                             ccw_device_move_to_orphanage);
+                queue_work(ccw_device_work, &cdev->private->kick_work);
+        } else
+                ccw_device_start_id(cdev, 0);
 }
 
 static void