Messages in this thread Patch in this message | | | Date | Thu, 7 Jun 2007 09:05:49 -0700 | From | "Paul E. McKenney" <> | Subject | [PATCH] Document the fact that RCU callbacks can run in parallel |
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Add an item to the RCU documentation checklist noting that RCU callbacks can run in parallel.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> ---
checklist.txt | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff -urpNa -X dontdiff linux-2.6.21/Documentation/RCU/checklist.txt linux-2.6.21-RCUdoc/Documentation/RCU/checklist.txt --- linux-2.6.21/Documentation/RCU/checklist.txt 2007-04-25 20:08:32.000000000 -0700 +++ linux-2.6.21-RCUdoc/Documentation/RCU/checklist.txt 2007-06-07 08:58:52.000000000 -0700 @@ -222,7 +222,15 @@ over a rather long period of time, but i deadlock as soon as the RCU callback happens to interrupt that acquisition's critical section. -13. SRCU (srcu_read_lock(), srcu_read_unlock(), and synchronize_srcu()) +13. RCU callbacks can be and are executed in parallel. In many cases, + the callback code simply wrappers around kfree(), so that this + is not an issue (or, more accurately, to the extent that it is + an issue, the memory-allocator locking handles it). However, + if the callbacks do manipulate a shared data structure, they + must use whatever locking or other synchronization is required + to safely access and/or modify that data structure. + +14. SRCU (srcu_read_lock(), srcu_read_unlock(), and synchronize_srcu()) may only be invoked from process context. Unlike other forms of RCU, it -is- permissible to block in an SRCU read-side critical section (demarked by srcu_read_lock() and srcu_read_unlock()), - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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