Commit-ID: 26fe8c643f7ca90e3d9ee2bf3c5d3d83cca650ec Gitweb: http://git.kernel.org/tip/26fe8c643f7ca90e3d9ee2bf3c5d3d83cca650ec Author: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Sat, 7 Mar 2009 16:11:38 -0800 Commit: Ingo Molnar <mingo@xxxxxxx> CommitDate: Sun, 8 Mar 2009 16:53:04 +0100 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@xxxxxxxxxxxxxxxxxx> Cc: akpm@xxxxxxxxxxxxxxxxxxxx Cc: dipankar@xxxxxxxxxx Cc: niv@xxxxxxxxxx Cc: dvhltc@xxxxxxxxxx LKML-Reference: <20090308001138.GA15335@xxxxxxxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- 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 6e25340..accfe2f 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. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|