unsigned long __get_wchan()

in kernel/process.c [322:345]

• 19 lines of code
• 6 McCabe index (conditional complexity)

unsigned long __get_wchan(struct task_struct *p)
{
	unsigned long sp, pc;
	unsigned long stack_page = (unsigned long) task_stack_page(p);
	int count = 0;

	sp = p->thread.sp;
	pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);

	do {
		if (sp < stack_page + sizeof(struct task_struct) ||
		    sp >= (stack_page + THREAD_SIZE) ||
		    pc == 0)
			return 0;
		if (!in_sched_functions(pc))
			return pc;

		/* Stack layout: sp-4: ra, sp-3: sp' */

		pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp);
		sp = SPILL_SLOT(sp, 1);
	} while (count++ < 16);
	return 0;
}