diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d57566b..55310db 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -107,6 +107,7 @@
 static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
 static void sd_print_result(struct scsi_disk *, int);
 
+static DEFINE_SPINLOCK(sd_index_lock);
 static DEFINE_IDA(sd_index_ida);
 
 /* This semaphore is used to mediate the 0->1 reference get in the
@@ -1914,7 +1915,9 @@
 		if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
 			goto out_put;
 
+		spin_lock(&sd_index_lock);
 		error = ida_get_new(&sd_index_ida, &index);
+		spin_unlock(&sd_index_lock);
 	} while (error == -EAGAIN);
 
 	if (error)
@@ -1936,7 +1939,9 @@
 	return 0;
 
  out_free_index:
+	spin_lock(&sd_index_lock);
 	ida_remove(&sd_index_ida, index);
+	spin_unlock(&sd_index_lock);
  out_put:
 	put_disk(gd);
  out_free:
@@ -1986,7 +1991,9 @@
 	struct scsi_disk *sdkp = to_scsi_disk(dev);
 	struct gendisk *disk = sdkp->disk;
 	
+	spin_lock(&sd_index_lock);
 	ida_remove(&sd_index_ida, sdkp->index);
+	spin_unlock(&sd_index_lock);
 
 	disk->private_data = NULL;
 	put_disk(disk);