|author||Paul E. McKenney <email@example.com>||2007-07-15 23:41:03 -0700|
|committer||Linus Torvalds <firstname.lastname@example.org>||2007-07-16 09:05:47 -0700|
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@example.com> Cc: Steven Rostedt <firstname.lastname@example.org> Signed-off-by: Andrew Morton <email@example.com> Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
Diffstat (limited to 'Documentation/RCU')
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index f4dffadbcb00..42b01bc2e1b4 100644
@@ -222,7 +222,15 @@ over a rather long period of time, but improvements are always welcome!
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()),