| Re: [PATCH] Introduce a handy list_first_entry macro [message #12119 is a reply to message #12078] |
Tue, 17 April 2007 17:11   |
Zach Brown
Messages: 1
Registered: April 2007
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Junior Member |
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On Tue, Apr 17, 2007 at 03:18:56PM +0400, Pavel Emelianov wrote:
> There are many places in the kernel where the construction like
>
> foo = list_entry(head->next, struct foo_struct, list);
>
> are used.
> The code might look more descriptive and neat if using the macro
>
> list_first_entry(head, type, member) \
> list_entry((head)->next, type, member)
> - dquot = list_entry(dirty->next, struct dquot, dq_dirty);
> + dquot = list_first_entry(dirty, struct dquot, dq_dirty);
I think it's more than just descriptive and neat. A common sneaky bug
is to accidentally pass &list->next into list_entry() instead of
list->next. This is easy to do because one is used to typing &list in
list_empty(), etc. So by following ->next in the macro we make the list
argument consistent in list_empty() and list_first_entry() and hopefully
reduce the risk of making that mistake.
I like it.
- z
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