From 5413e24c943da33306047fc091fa34fa4f261b3b Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 15 Mar 2016 13:40:28 -0700 Subject: [PATCH] documentation: Sharpen up the no-readers quick quiz Signed-off-by: Paul E. McKenney --- .../RCU/Design/Requirements/Requirements.html | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html index acdad96f78e9..85cf2238fd08 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.html +++ b/Documentation/RCU/Design/Requirements/Requirements.html @@ -1002,18 +1002,21 @@ obligation to wait for these new readers.   Quick Quiz: - 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 all + 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? Answer: - No. + For no time at all. Even if synchronize_rcu() were to wait until all readers had completed, a new reader might start immediately after synchronize_rcu() completed. Therefore, the code following - synchronize_rcu() cannot rely on there being no readers - in any case. + synchronize_rcu() can never rely on there being + no readers.