[S390] dcssblk: fix race in dcssblk_add_store()

Concurrently adding the same segment may lead to duplicate device_register()
calls, which will trigger an error in kobject code:
"... don't try to register things with the same name in the same directory".
This patch adds a check to avoid this.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 01fcdd91b846..db85f1fb131e 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -384,6 +384,10 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char
          * get minor, add to list
          */
         down_write(&dcssblk_devices_sem);
+        if (dcssblk_get_segment_by_name(local_buf)) {
+                rc = -EEXIST;
+                goto release_gd;
+        }
         rc = dcssblk_assign_free_minor(dev_info);
         if (rc) {
                 up_write(&dcssblk_devices_sem);