s390/cio: fix unlocked access of global bitmap

Access to the slow_subchannel_set has to be secured via the
slow_subchannel_lock.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 4eb2a54e64f2..8c2cb87bccc5 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -546,7 +546,9 @@ static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
                 case -ENOMEM:
                 case -EIO:
                         /* These should abort looping */
+                        spin_lock_irq(&slow_subchannel_lock);
                         idset_sch_del_subseq(slow_subchannel_set, schid);
+                        spin_unlock_irq(&slow_subchannel_lock);
                         break;
                 default:
                         rc = 0;