[S390] subchannel register/unregister mutex.
Add a reg_mutex to prevent unregistering a subchannel before it has been
registered. Since 2.6.17, we've seen oopses in kslowcrw when a device is
found to be not operational during sense id when doing initial device
recognition; it is not clear yet why that particular problem was not (yet)
observed with earlier kernels...
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 6fec90e..f27b2b8 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -519,6 +519,7 @@
memset(sch, 0, sizeof(struct subchannel));
spin_lock_init(&sch->lock);
+ mutex_init(&sch->reg_mutex);
/* Set a name for the subchannel */
snprintf (sch->dev.bus_id, BUS_ID_SIZE, "0.%x.%04x", schid.ssid,
