The current checklist.rst file correctly notes that RCU callbacks execute in BH context, and cannot block. This commit adds words advising people needing callbacks to block to use workqueues, for example, by replacing call_rcu() with queue_rcu_work(). Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- Documentation/RCU/checklist.rst | 3 +++ 1 file changed, 3 insertions(+) diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst index 5eedef027d922..2db206fc3465f 100644 --- a/Documentation/RCU/checklist.rst +++ b/Documentation/RCU/checklist.rst @@ -190,6 +190,9 @@ over a rather long period of time, but improvements are always welcome! 5. If call_rcu() or call_srcu() is used, the callback function will be called from softirq context. In particular, it cannot block. + If you need the callback to block, run that code in a workqueue + handler scheduled from the callback. The queue_rcu_work() + function does this for you in the case of call_rcu(). 6. Since synchronize_rcu() can block, it cannot be called from any sort of irq context. The same rule applies -- 2.31.1.189.g2e36527f23
