Where is run_node defined in the sched_fair.c of Linux 2.6.33?

[Sreyan Chakravarty]

I am reading Robert Love's Book Linux Kernel Development(
https://rads.stackoverflow.com/amzn/click/com/B003V4ATI0).

It uses the 2.6.33 kernel for demonstration.

I have been going through certain parts of the source and can't find out
where is the initial definition of many things. A lot of things are just
used, like "magic" without me finding the definition.

One example:

static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
{
struct rb_node *left = cfs_rq->rb_leftmost;

if (!left)
return NULL;

return rb_entry(left, struct sched_entity, run_node);
}

static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
{
struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);

if (!last)
return NULL;

return rb_entry(last, struct sched_entity, run_node);
}

This in kernel/sched_fair.c lines 384 and 394 in 2.6.33 kernel.

Where is the run_node coming from ?

I have grep ed(
https://livegrep.com/search/linuxq=run_node&fold_case=auto&regex=false&context=true
<https://livegrep.com/search/linux?q=run_node&fold_case=auto&regex=false&context=true>)
the entire source base over here, and I have not found any definition of
run_node that would allow it to be used like this.

There is a declaration(
https://github.com/torvalds/linux/blob/219d54332a09e8d8741c1e1982f5eae56099de85/include/linux/sched.h#L448)
in the sched_entity structure, but nothing outside of it that would allow
it to be used like this.

I cannot understand how things are organized, its really confusing.

What is going on ?
-- 
Regards,
Sreyan Chakravarty
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