[SCSI] zfcp: Acquire qdio_stat_lock when reading the queue utilization

req_q_util is not atomic, so the qdio_stat_lock must be held when
reading this variable.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/s390/scsi/zfcp_sysfs.c b/drivers/s390/scsi/zfcp_sysfs.c
index 3e51e64d1108..0fe5cce818cb 100644
--- a/drivers/s390/scsi/zfcp_sysfs.c
+++ b/drivers/s390/scsi/zfcp_sysfs.c
@@ -494,9 +494,14 @@ static ssize_t zfcp_sysfs_adapter_q_full_show(struct device *dev,
         struct Scsi_Host *scsi_host = class_to_shost(dev);
         struct zfcp_adapter *adapter =
                 (struct zfcp_adapter *) scsi_host->hostdata[0];
+        u64 util;
+
+        spin_lock_bh(&adapter->qdio_stat_lock);
+        util = adapter->req_q_util;
+        spin_unlock_bh(&adapter->qdio_stat_lock);
 
         return sprintf(buf, "%d %llu\n", atomic_read(&adapter->qdio_outb_full),
-                       (unsigned long long)adapter->req_q_util);
+                       (unsigned long long)util);
 }
 static DEVICE_ATTR(queue_full, S_IRUGO, zfcp_sysfs_adapter_q_full_show, NULL);