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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 <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul E. McKenney 2007-07-15 23:41:03 -07:00 committed by Linus Torvalds
parent 4d3b573ad9
commit ef48bd2461
1 changed files with 9 additions and 1 deletions
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10
Documentation/RCU/checklist.txt
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@ -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()),