fs: synchronize_rcu when unregister_filesystem success not failure
Milton Miller [Thu, 14 Apr 2011 15:30:08 +0000 (10:30 -0500)]
While checking unregister_filesystem for saftey vs extra calls for
"ext4: register ext2 and ext3 alias after ext4" I realized that
the synchronize_rcu() was called on the error path but not on
the success path.

Cc: stable (2.6.38)
Signed-off-by: Milton Miller <miltonm@bga.com>
[ This probably won't really make a difference since commit d863b50ab013
  ("vfs: call rcu_barrier after ->kill_sb()"), but it's the right thing
  to do.  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/filesystems.c

index 751d6b2..0845f84 100644 (file)
@@ -110,14 +110,13 @@ int unregister_filesystem(struct file_system_type * fs)
                        *tmp = fs->next;
                        fs->next = NULL;
                        write_unlock(&file_systems_lock);
+                       synchronize_rcu();
                        return 0;
                }
                tmp = &(*tmp)->next;
        }
        write_unlock(&file_systems_lock);
 
-       synchronize_rcu();
-
        return -EINVAL;
 }