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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-03-10 20:55:57 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-03-10 23:55:11 +0100 |
commit | 0612ea00a010e36fde61e7b7649a1105b0ef1080 (patch) | |
tree | 3e543336430dafbd67237075954f9ce0ccab2e65 | |
parent | kernel/user.c: fix a memory leak when freeing up non-init usernamespaces users (diff) | |
download | linux-0612ea00a010e36fde61e7b7649a1105b0ef1080.tar.xz linux-0612ea00a010e36fde61e7b7649a1105b0ef1080.zip |
rcu: documentation 1Q09 update
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@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | Documentation/RCU/checklist.txt | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 6e253407b3dc..accfe2f5247d 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -298,3 +298,15 @@ over a rather long period of time, but improvements are always welcome! 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. |