types: Update obsolete callback_head comment

The comment header for callback_head (and thus for rcu_head) states that
the bottom two bits of a pointer to these structures must be zero.  This
is obsolete:  The new requirement is that only the bottom bit need be
zero.  This commit therefore updates this comment.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/include/linux/types.h b/include/linux/types.h
index 1e7bd24848fcb54cae26bdd10597f6ea80afd46f..258099a4ed82b1b3dd8199b7c905491c935a73a7 100644 (file)
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -209,7 +209,7 @@ struct ustat {
  * naturally due ABI requirements, but some architectures (like CRIS) have
  * weird ABI and we need to ask it explicitly.
  *
- * The alignment is required to guarantee that bits 0 and 1 of @next will be
+ * The alignment is required to guarantee that bit 0 of @next will be
  * clear under normal conditions -- as long as we use call_rcu(),
  * call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
  *