aboutsummaryrefslogtreecommitdiff
path: root/Documentation/RCU/UP.txt
diff options
context:
space:
mode:
authorPaul E. McKenney <paulmck@us.ibm.com>2005-05-01 08:59:05 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-05-01 08:59:05 -0700
commita83f1fe27f7252a2b73b4f22066e92bf99bd595b (patch)
treeb6c4dd485fff268f86f396a85aad88cf29783dcd /Documentation/RCU/UP.txt
parentfbd568a3e61a7decb8a754ad952aaa5b5c82e9e5 (diff)
downloadlinux-linaro-stable-a83f1fe27f7252a2b73b4f22066e92bf99bd595b.tar.gz
[PATCH] Update RCU documentation
Update the RCU documentation to allow for the new synchronize_rcu() and synchronize_sched() primitives. Fix a few other nits as well. Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/RCU/UP.txt')
-rw-r--r--Documentation/RCU/UP.txt8
1 files changed, 4 insertions, 4 deletions
diff --git a/Documentation/RCU/UP.txt b/Documentation/RCU/UP.txt
index 551a803d82a8..3bfb84b3b7db 100644
--- a/Documentation/RCU/UP.txt
+++ b/Documentation/RCU/UP.txt
@@ -2,11 +2,11 @@ RCU on Uniprocessor Systems
A common misconception is that, on UP systems, the call_rcu() primitive
-may immediately invoke its function, and that the synchronize_kernel
+may immediately invoke its function, and that the synchronize_rcu()
primitive may return immediately. The basis of this misconception
is that since there is only one CPU, it should not be necessary to
wait for anything else to get done, since there are no other CPUs for
-anything else to be happening on. Although this approach will sort of
+anything else to be happening on. Although this approach will -sort- -of-
work a surprising amount of the time, it is a very bad idea in general.
This document presents two examples that demonstrate exactly how bad an
idea this is.
@@ -44,14 +44,14 @@ its arguments would cause it to fail to make the fundamental guarantee
underlying RCU, namely that call_rcu() defers invoking its arguments until
all RCU read-side critical sections currently executing have completed.
-Quick Quiz: why is it -not- legal to invoke synchronize_kernel() in
+Quick Quiz: why is it -not- legal to invoke synchronize_rcu() in
this case?
Summary
Permitting call_rcu() to immediately invoke its arguments or permitting
-synchronize_kernel() to immediately return breaks RCU, even on a UP system.
+synchronize_rcu() to immediately return breaks RCU, even on a UP system.
So do not do it! Even on a UP system, the RCU infrastructure -must-
respect grace periods.