From d3d3a3ccc4a8f1f254fb6788081f35bebe374174 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 28 Mar 2017 19:57:45 -0700 Subject: [PATCH] doc: Emphasize that "toy" RCU requires recursive rwlock Reported-by: "yangzc@uit.com.cn" Signed-off-by: Paul E. McKenney --- Documentation/RCU/whatisRCU.txt | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt index 6b0337008f9c..8c131a1c62ea 100644 --- a/Documentation/RCU/whatisRCU.txt +++ b/Documentation/RCU/whatisRCU.txt @@ -562,7 +562,9 @@ This section presents a "toy" RCU implementation that is based on familiar locking primitives. Its overhead makes it a non-starter for real-life use, as does its lack of scalability. It is also unsuitable for realtime use, since it allows scheduling latency to "bleed" from -one read-side critical section to another. +one read-side critical section to another. It also assumes recursive +reader-writer locks: If you try this with non-recursive locks, and +you allow nested rcu_read_lock() calls, you can deadlock. However, it is probably the easiest implementation to relate to, so is a good starting point. -- 2.39.5