Document the fact that RCU callbacks can run in parallel
Subsystems (2)
PATCH 1/1 Document the fact that RCU callbacks can run in parallel
Add an item to the RCU documentation checklist noting that RCU callbacks can run in parallel.
Signed-off-by Paul E. McKenney <[email protected]>
---
checklist.txt | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
Documentation/RCU/checklist.txt +9 -1
@@ -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()),