1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/s390/scsi/zfcp_sysfs.c b/drivers/s390/scsi/zfcp_sysfs.c
index c66af27b230b..1e0eb089dfba 100644
--- a/drivers/s390/scsi/zfcp_sysfs.c
+++ b/drivers/s390/scsi/zfcp_sysfs.c
@@ -227,6 +227,8 @@ static ssize_t zfcp_sysfs_port_rescan_store(struct device *dev,
 static ZFCP_DEV_ATTR(adapter, port_rescan, S_IWUSR, NULL,
                      zfcp_sysfs_port_rescan_store);
 
+DEFINE_MUTEX(zfcp_sysfs_port_units_mutex);
+
 static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
                                             struct device_attribute *attr,
                                             const char *buf, size_t count)
@@ -249,6 +251,16 @@ static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
         else
                 retval = 0;
 
+        mutex_lock(&zfcp_sysfs_port_units_mutex);
+        if (atomic_read(&port->units) > 0) {
+                retval = -EBUSY;
+                mutex_unlock(&zfcp_sysfs_port_units_mutex);
+                goto out;
+        }
+        /* port is about to be removed, so no more unit_add */
+        atomic_set(&port->units, -1);
+        mutex_unlock(&zfcp_sysfs_port_units_mutex);
+
         write_lock_irq(&adapter->port_list_lock);
         list_del(&port->list);
         write_unlock_irq(&adapter->port_list_lock);
@@ -289,12 +301,14 @@ static ssize_t zfcp_sysfs_unit_add_store(struct device *dev,
 {
         struct zfcp_port *port = container_of(dev, struct zfcp_port, dev);
         u64 fcp_lun;
+        int retval;
 
         if (strict_strtoull(buf, 0, (unsigned long long *) &fcp_lun))
                 return -EINVAL;
 
-        if (zfcp_unit_add(port, fcp_lun))
-                return -EINVAL;
+        retval = zfcp_unit_add(port, fcp_lun);
+        if (retval)
+                return retval;
 
         return count;
 }