[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>

1 files changed, 5 insertions, 1 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)