From 8750dfe6fda4aca9cc02b3f652d14b14b49bccfb Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 4 Nov 2022 11:00:14 -0700 Subject: [PATCH] doc: Update NMI-RCU.rst This commit updates NMI-RCU.rst to highlight the ancient heritage of the example code and to discourage wanton compiler "optimizations". Signed-off-by: Paul E. McKenney --- Documentation/RCU/NMI-RCU.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Documentation/RCU/NMI-RCU.rst b/Documentation/RCU/NMI-RCU.rst index 2a92bc685ef1..dff60a80b386 100644 --- a/Documentation/RCU/NMI-RCU.rst +++ b/Documentation/RCU/NMI-RCU.rst @@ -8,7 +8,7 @@ Although RCU is usually used to protect read-mostly data structures, it is possible to use RCU to provide dynamic non-maskable interrupt handlers, as well as dynamic irq handlers. This document describes how to do this, drawing loosely from Zwane Mwaikambo's NMI-timer -work in "arch/x86/kernel/traps.c". +work in an old version of "arch/x86/kernel/traps.c". The relevant pieces of code are listed below, each followed by a brief explanation:: @@ -116,7 +116,7 @@ Answer to Quick Quiz: This same sad story can happen on other CPUs when using a compiler with aggressive pointer-value speculation - optimizations. + optimizations. (But please don't!) More important, the rcu_dereference_sched() makes it clear to someone reading the code that the pointer is