Re: [PATCH 1/2] rcu: introduce list_last_or_null_rcu

From: Dan Streetman
Date: Thu May 28 2015 - 17:31:05 EST


On Thu, May 28, 2015 at 5:28 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Thu, 28 May 2015 17:19:40 -0400
> Dan Streetman <ddstreet@xxxxxxxx> wrote:
>
>> >> oh, ok. how do we do type-generic inline funcs? return void*?
>> >
>> > I was hoping that you would tell me. I use macros in that case.
>>
>> ha, if I ever get to the point where i think i know more than you,
>> i'll let you know ;-)
>
> static inline struct list_head *
> list_last_or_null_rcu(struct list_head *ptr)
> {
> struct list_head *entry;
> struct list_head *last;
>
> for (entry = list_next_rcu(ptr);
> entry != ptr; entry = list_next_rcu(entry))
> last = __entry;
> if (last != ptr)
> return last;
> return NULL;
> }
>
> #define list_last_or_null_entry_rcu(ptr, type, member) \
> ({ \
> struct list_head *__ptr = list_last_or_null_rcu(ptr); \
> __ptr ? list_entry_rcu(__ptr, type, member) : NULL; \
> })

well sure :-)

however, the rcu list function currently doesn't include "entry" in
the function name, but returns the list entry (not the list_head).
that could be changed, but all callers would need to change, too.

>
> -- Steve
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