On Mon, 25 Sep 2017, Thomas Gleixner wrote: > On Thu, 7 Sep 2017, Paul Burton wrote: > > Up until now per_cpu_devid interrupts have not supported sharing. On > > MIPS we have some percpu interrupts which are shared in many systems - > > a single CPU interrupt line may be used to indicate a timer interrupt, > > performance counter interrupt or fast debug channel interrupt. We have > > up until now supported this with a series of hacks, wherein drivers call > > each other's interrupt handlers & our MIPS GIC irqchip driver includes a > > hack which configures the interrupt(s) for all CPUs. In order to allow > > this mess to be cleaned up, this patch introduces support for shared > > per_cpu_devid interrupts. > > > > The major portion of this is supporting per_cpu_devid interrupts in > > __handle_irq_event_percpu() and then making use of this, via > > handle_irq_event_percpu(), from handler_percpu_devif_irq() to invoke the > > handler for all actions associated with the shared interrupt. This does > > have a few side effects worth noting: > > > > - per_cpu_devid interrupts will now add to the entropy pool via > > add_interrupt_randomness(), where they previously did not. > > > > - per_cpu_devid interrupts will record timings when IRQS_TIMINGS is > > set, via record_irq_time(), where they previously did not. > > > > - per_cpu_devid interrupts will handle an IRQ_WAKE_THREAD return from > > their handlers to wake a thread, where they previously did not. > > That's broken because it lacks the magic synchronization which is described > in the comment in __irq_wake_thread(). Aside of that to make that work at all would require per cpu threads and not a single systemwide thread. Thanks, tglx
