ipi_interrupt
extern irqreturn_t ipi_interrupt(int, void *);
if (request_irq(IPI_IRQ, ipi_interrupt, IRQF_PERCPU, "IPI", NULL))
static irqreturn_t ipi_interrupt(int irq, void *dev_id);
if (request_irq(irq, ipi_interrupt, IRQF_PERCPU, "ipi", NULL))