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Diffstat (limited to 'Documentation/RCU/checklist.rst')
| -rw-r--r-- | Documentation/RCU/checklist.rst | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst index 2efed9926c3f..bb7128eb322e 100644 --- a/Documentation/RCU/checklist.rst +++ b/Documentation/RCU/checklist.rst @@ -314,6 +314,13 @@ over a rather long period of time, but improvements are always welcome! shared between readers and updaters. Additional primitives are provided for this case, as discussed in lockdep.txt. + One exception to this rule is when data is only ever added to + the linked data structure, and is never removed during any + time that readers might be accessing that structure. In such + cases, READ_ONCE() may be used in place of rcu_dereference() + and the read-side markers (rcu_read_lock() and rcu_read_unlock(), + for example) may be omitted. + 10. Conversely, if you are in an RCU read-side critical section, and you don't hold the appropriate update-side lock, you -must- use the "_rcu()" variants of the list macros. Failing to do so |