On 1/12/2022 10:16 AM, Ilpo Järvinen wrote:
On Wed, 12 Jan 2022, Andy Shevchenko wrote:
On Wed, Jan 12, 2022 at 04:24:52PM +0200, Ilpo Järvinen wrote:
On Wed, 12 Jan 2022, Andy Shevchenko wrote:
On Tue, Jan 11, 2022 at 08:55:58PM -0800, Martinez, Ricardo wrote:
On 12/16/2021 3:08 AM, Ilpo Järvinen wrote:
On Mon, 6 Dec 2021, Ricardo Martinez wrote:
+ if (req->entry.next == &ring->gpd_ring)
+ return list_first_entry(&ring->gpd_ring, struct cldma_request, entry);
+
+ return list_next_entry(req, entry);
...
+ if (req->entry.prev == &ring->gpd_ring)
+ return list_last_entry(&ring->gpd_ring, struct cldma_request, entry);
+
+ return list_prev_entry(req, entry);
...
Wouldn't these two seems generic enough to warrant adding something like
list_next/prev_entry_circular(...) to list.h?
Agree, in the upcoming version I'm planning to include something like this
to list.h as suggested:
I think you mean for next and prev, i.o.w. two helpers, correct?
#define list_next_entry_circular(pos, ptr, member) \
One thing I missed earlier, the sigrature should instead of ptr have head:
#define list_next_entry_circular(pos, head, member)
((pos)->member.next == (ptr) ? \
I believe this is list_entry_is_head().
It takes .next so it's not the same as list_entry_is_head() and
list_entry_is_last() doesn't exist.
But we have list_last_entry(). So, what about
list_last_entry() == pos ? first : next;
and counterpart
list_first_entry() == pos ? last : prev;
?
Yes, although now that I think it more, using them implies the head
element has to be always accessed. It might be marginally cache friendlier
to use list_entry_is_head you originally suggested but get the next entry
first:
({
typeof(pos) next__ = list_next_entry(pos, member); \
!list_entry_is_head(next__, head, member) ? next__ : list_next_entry(next__, member);
})
(This was written directly to email, entirely untested).
Here, the head element would only get accessed when we really need to walk
through it.
I'm not sure if list_next_entry() will work for the last element, what
about using list_is_last()?
This way we avoid accessing head if not needed and does not to use
'container_of()' on (pos)->member.next.
(list_is_last(&(pos)->member, head) ? \
list_first_entry(head, typeof(*(pos)), member) : \
list_next_entry(pos, member))
(untested)
list_first_entry(ptr, typeof(*(pos)), member) : \
list_next_entry(pos, member))
