On Tue, Nov 30, 2021 at 12:28:41PM +0100, Nicolas Saenz Julienne wrote: > Hi All, > while going over the IRQ/NMI entry code I've found a small 'inconsistency': > while in the IRQ entry path, we inform RCU of the context change *before* > incrementing the preempt counter, the opposite happens for the NMI entry > path. This applies to both arm64 and x86[1]. > > Actually, rcu_nmi_enter() — which is also the main RCU context switch function > for the IRQ entry path — uses the preempt counter to verify it's not in NMI > context. So it would make sense to assume all callers have the same updated > view of the preempt count, which isn't true ATM. > > I'm sure there an obscure/non-obvious reason for this, right? At least I can't find an immediate reason for it either :-) Thanks!
