2 files changed, 14 insertions, 9 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 93f2b1d18398..15c8b7b25a9b 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -223,6 +223,12 @@ static int linear_run (mddev_t *mddev)
         return 0;
 }
 
+static void free_conf(struct rcu_head *head)
+{
+        linear_conf_t *conf = container_of(head, linear_conf_t, rcu);
+        kfree(conf);
+}
+
 static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
 {
         /* Adding a drive to a linear array allows the array to grow.
@@ -233,7 +239,7 @@ static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
          * The current one is never freed until the array is stopped.
          * This avoids races.
          */
-        linear_conf_t *newconf;
+        linear_conf_t *newconf, *oldconf;
 
         if (rdev->saved_raid_disk != mddev->raid_disks)
                 return -EINVAL;
@@ -245,11 +251,12 @@ static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
         if (!newconf)
                 return -ENOMEM;
 
-        newconf->prev = mddev->private;
+        oldconf = rcu_dereference(mddev->private);
         mddev->raid_disks++;
         rcu_assign_pointer(mddev->private, newconf);
         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
         set_capacity(mddev->gendisk, mddev->array_sectors);
+        call_rcu(&oldconf->rcu, free_conf);
         return 0;
 }
 
@@ -261,14 +268,12 @@ static int linear_stop (mddev_t *mddev)
          * We do not require rcu protection here since
          * we hold reconfig_mutex for both linear_add and
          * linear_stop, so they cannot race.
+         * We should make sure any old 'conf's are properly
+         * freed though.
          */
-
+        rcu_barrier();
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
-        do {
-                linear_conf_t *t = conf->prev;
-                kfree(conf);
-                conf = t;
-        } while (conf);
+        kfree(conf);
 
         return 0;
 }
diff --git a/drivers/md/linear.h b/drivers/md/linear.h
index 599e5c1bbb01..0ce29b61605a 100644
--- a/drivers/md/linear.h
+++ b/drivers/md/linear.h
@@ -10,9 +10,9 @@ typedef struct dev_info dev_info_t;
 
 struct linear_private_data
 {
-        struct linear_private_data *prev;       /* earlier version */
         sector_t                array_sectors;
         dev_info_t              disks[0];
+        struct rcu_head         rcu;
 };