[S390] Fix reboot hang on LPARs

Reboot hangs on LPARs without diag308 support. The reason for this is,
that before the reboot is done, the channel subsystem is shut down.
During the reset on each possible subchannel a "store subchannel" is
done. This operation can end in a program check interruption, if the
specified subchannel set is not implemented by the hardware. During
the reset, currently we do not have a program check handler, which
leads to the described kernel bug. We install now a new program check
handler for the reboot code to fix this problem.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 7835a714a405..3a403f195cf8 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -871,11 +871,32 @@ __clear_subchannel_easy(struct subchannel_id schid)
         return -EBUSY;
 }
 
+static int pgm_check_occured;
+
+static void cio_reset_pgm_check_handler(void)
+{
+        pgm_check_occured = 1;
+}
+
+static int stsch_reset(struct subchannel_id schid, volatile struct schib *addr)
+{
+        int rc;
+
+        pgm_check_occured = 0;
+        s390_reset_pgm_handler = cio_reset_pgm_check_handler;
+        rc = stsch(schid, addr);
+        s390_reset_pgm_handler = NULL;
+        if (pgm_check_occured)
+                return -EIO;
+        else
+                return rc;
+}
+
 static int __shutdown_subchannel_easy(struct subchannel_id schid, void *data)
 {
         struct schib schib;
 
-        if (stsch_err(schid, &schib))
+        if (stsch_reset(schid, &schib))
                 return -ENXIO;
         if (!schib.pmcw.ena)
                 return 0;
@@ -972,7 +993,7 @@ static int __reipl_subchannel_match(struct subchannel_id schid, void *data)
         struct schib schib;
         struct sch_match_id *match_id = data;
 
-        if (stsch_err(schid, &schib))
+        if (stsch_reset(schid, &schib))
                 return -ENXIO;
         if (schib.pmcw.dnv &&
             (schib.pmcw.dev == match_id->devid.devno) &&