Hello, Frederic, Boqun just asked if RCU callbacks ran in BH-disabled context to avoid concurrent execution of the same callback. Of course, this raises the question of whether a self-posting callback can have two instances of itself running concurrently while a CPU is in the process of transitioning between softirq and rcuo invocation of callbacks. I believe that the answer is "no" because BH-disabled context is an implicit RCU read-side critical section. Therefore, the initial invocation of the RCU callback must complete in order for a new grace period to complete, and a new grace period must complete before the second invocation of that same callback to start. Does that make sense, or am I missing something? Thanx, Paul
