On Fri, 22 Jun 2018 06:28:43 -0700 "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> It has been some years since I traced the code flow, but what happened > back then is that it switches itself from an interrupt handler to not > without actually returning from the interrupt. This can only happen when > interrupting a non-idle process, thankfully, and RCU's dyntick-idle code > relies on this restriction. If I remember correctly, the code ends up > executing in the context of the interrupted process, but it has been some > years, so please apply appropriate skepticism. If irq_enter() is not paired with irq_exit() then major things will break. Especially since that's how in_interrupt() and friends rely on to work. Now, perhaps rcu_irq_enter() is called elsewhere (as a git grep appears it may be), and that rcu_irq_enter() may not be paired with rcu_irq_exit(). But that's not anything to do with the irq_enter() and irq_exit() routines being paired or not. -- Steve
