The patch titled
rcu: documentation 1Q09 update
has been added to the -mm tree. Its filename is
rcu-documentation-1q09-update.patch
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------------------------------------------------------
Subject: rcu: documentation 1Q09 update
From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Update the RCU documentation to call out the need for callers of
primitives like call_rcu() and synchronize_rcu() to prevent subsequent RCU
readers from hazard.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/RCU/checklist.txt | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff -puN Documentation/RCU/checklist.txt~rcu-documentation-1q09-update Documentation/RCU/checklist.txt
--- a/Documentation/RCU/checklist.txt~rcu-documentation-1q09-update
+++ a/Documentation/RCU/checklist.txt
@@ -298,3 +298,15 @@ over a rather long period of time, but i
Note that, rcu_assign_pointer() and rcu_dereference() relate to
SRCU just as they do to other forms of RCU.
+
+15. The whole point of call_rcu(), synchronize_rcu(), and friends
+ is to wait until all pre-existing readers have finished before
+ carrying out some otherwise-destructive operation. It is
+ therefore critically important to -first- remove any path
+ that readers can follow that could be affected by the
+ destructive operation, and -only- -then- invoke call_rcu(),
+ synchronize_rcu(), or friends.
+
+ Because these primitives only wait for pre-existing readers,
+ it is the caller's responsibility to guarantee safety to
+ any subsequent readers.
_
Patches currently in -mm which might be from paulmck@xxxxxxxxxxxxxxxxxx are
origin.patch
idr-make-idr_remove_all-do-removal-before-free_layer.patch
rcu-documentation-1q09-update.patch
linux-next.patch
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