On 24/06/20 20:57, Marc Zyngier wrote:
> @@ -696,9 +696,76 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>
> if ((unsigned)ipinr < NR_IPI)
> trace_ipi_exit_rcuidle(ipi_types[ipinr]);
> +}
> +
> +/* Legacy version, should go away once all irqchips have been converted */
> +void handle_IPI(int ipinr, struct pt_regs *regs)
> +{
> + struct pt_regs *old_regs = set_irq_regs(regs);
> +
> + irq_enter();
> + do_handle_IPI(ipinr);
> + irq_exit();
> +
> set_irq_regs(old_regs);
> }
>
> +static irqreturn_t ipi_handler(int irq, void *data)
> +{
> + do_handle_IPI(irq - ipi_irq_base);
> + return IRQ_HANDLED;
> +}
> +
> +static void ipi_send(const struct cpumask *target, unsigned int ipi)
> +{
> + __ipi_send_mask(ipi_desc[ipi], target);
> +}
> +
> +static void ipi_setup(int cpu)
> +{
> + if (ipi_irq_base) {
> + int i;
> +
> + for (i = 0; i < nr_ipi; i++)
> + enable_percpu_irq(ipi_irq_base + i, 0);
> + }
> +}
> +
> +static void ipi_teardown(int cpu)
> +{
> + if (ipi_irq_base) {
> + int i;
> +
> + for (i = 0; i < nr_ipi; i++)
> + disable_percpu_irq(ipi_irq_base + i);
> + }
> +}
> +
> +void __init set_smp_ipi_range(int ipi_base, int n)
> +{
> + int i;
> +
> + WARN_ON(n < MAX_IPI);
> + nr_ipi = min(n, MAX_IPI);
I got confused by that backtrace thing and NR_IPI vs MAX_IPI.
I think I got it now : we don't want to call trace_ipi_raise() for
IPI_CPU_BACKTRACE *but* we still need to alloc the desc and route it
through the generic IPI layers.
The only difference I can tell is that now we will get some trace events
for it via the handler entry/exit tracepoints - that shouldn't cause any
issue.
> +
> + for (i = 0; i < nr_ipi; i++) {
> + int err;
> +
> + err = request_percpu_irq(ipi_base + i, ipi_handler,
> + "IPI", &irq_stat);
> + WARN_ON(err);
> +
> + ipi_desc[i] = irq_to_desc(ipi_base + i);
> + irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
> + }
> +
> + ipi_irq_base = ipi_base;
> + set_smp_cross_call(ipi_send);
> +
> + /* Setup the boot CPU immediately */
> + ipi_setup(smp_processor_id());
> +}
> +
> void smp_send_reschedule(int cpu)
> {
> smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
