Re: [PATCH RFC] struct list_node

From: Randy Dunlap
Date: Sun Jun 10 2007 - 13:13:17 EST

On Sun, 10 Jun 2007 15:11:30 +1000 Rusty Russell wrote:

> The current list.h has the same type for list elements and list heads
> even though most code and coders treat them as distinct.
> I've had a version of list.h (for userspace work) for about a year
> which uses a different type for nodes and it works very well: code is
> clearer, and mistakes like list_add() argument reversal are detected.
> Code which really wants to treat a list node as a head can append ".h".
> To avoid a massive flag day, this patch uses gcc's "cast to union" to
> allow either list_head or list_node in various places.
> Notes:
> 1) A new function in_list() is introduced, equivalent to "list_empty(&e)"
> but for nodes.

in_list() sounds like it would scan an entire list and return true
if &e is found, false if &e is not found...

and that's what the short description sounds like to me as well...

I'm just confuzed. And you aren't supposed to write confuzing
interfaces. :)

> +/**
> + * in_list - tests whether element is in a list.
> + * @entry: the entry to test
> + *
> + * Returns false if the list elem was deleted from list (except __list_del)

What is "elem"? How can this function determine is a list element was
deleted vs. was never added?

> + */
> +static inline int in_list(const struct list_node *entry)
> +{
> + return entry-> == &entry->h;
> }

*** Remember to use Documentation/SubmitChecklist when testing your code ***
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at