documentation: Sharpen up the no-readers quick quiz
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html
index acdad96..85cf223 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.html
+++ b/Documentation/RCU/Design/Requirements/Requirements.html
@@ -1002,18 +1002,21 @@
<tr><th> </th></tr>
<tr><th align="left">Quick Quiz:</th></tr>
<tr><td>
- Suppose that synchronize_rcu() did wait until all readers had completed.
- Would the updater be able to rely on this?
+ Suppose that synchronize_rcu() did wait until <i>all</i>
+ readers had completed instead of waiting only on
+ pre-existing readers.
+ For how long would the updater be able to rely on there
+ being no readers?
</td></tr>
<tr><th align="left">Answer:</th></tr>
<tr><td bgcolor="#ffffff"><font color="ffffff">
- No.
+ For no time at all.
Even if <tt>synchronize_rcu()</tt> were to wait until
all readers had completed, a new reader might start immediately after
<tt>synchronize_rcu()</tt> completed.
Therefore, the code following
- <tt>synchronize_rcu()</tt> cannot rely on there being no readers
- in any case.
+ <tt>synchronize_rcu()</tt> can <i>never</i> rely on there being
+ no readers.
</font></td></tr>
<tr><td> </td></tr>
</table>
