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-rw-r--r--Documentation/RCU/UP.txt6
1 files changed, 2 insertions, 4 deletions
diff --git a/Documentation/RCU/UP.txt b/Documentation/RCU/UP.txt
index 90ec5341ee98..53bde717017b 100644
--- a/Documentation/RCU/UP.txt
+++ b/Documentation/RCU/UP.txt
@@ -86,10 +86,8 @@ even on a UP system. So do not do it! Even on a UP system, the RCU
infrastructure -must- respect grace periods, and -must- invoke callbacks
from a known environment in which no locks are held.
-It -is- safe for synchronize_sched() and synchronize_rcu_bh() to return
-immediately on an UP system. It is also safe for synchronize_rcu()
-to return immediately on UP systems, except when running preemptable
-RCU.
+Note that it -is- safe for synchronize_rcu() to return immediately on
+UP systems, including !PREEMPT SMP builds running on UP systems.
Quick Quiz #3: Why can't synchronize_rcu() return immediately on
UP systems running preemptable RCU?