慢慢欣赏 ftrace （二）进程和中断状态填充方法

void
tracing_generic_entry_update(struct trace_entry *entry, unsigned short type,
			     unsigned long flags, int pc)
{
	struct task_struct *tsk = current;	// 找到进程任务描述符

	entry->preempt_count		= pc & 0xff;	// 抢占计数
	entry->pid			= (tsk) ? tsk->pid : 0;	// 进程pid
	entry->type			= type;
	entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
		(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |	// 中断的各种状态填充
#else
		TRACE_FLAG_IRQS_NOSUPPORT |
#endif
		((pc & NMI_MASK    ) ? TRACE_FLAG_NMI     : 0) |
		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
		((pc & SOFTIRQ_OFFSET) ? TRACE_FLAG_SOFTIRQ : 0) |
		(tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) |
		(test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0);
}