Called immediately before the irq action handler
void trace_irq_handler_entry(int irq, struct irqaction * action);
irq
irq number
action
pointer to struct irqaction
The struct irqaction pointed to by action contains various information about the handler, including the device name, action->name, and the device id, action->dev_id. When used in conjunction with the irq_handler_exit tracepoint, we can figure out irq handler latencies.